The Chevrolet Corvette C7.R was the race-going equivalent of the Chevrolet Corvette C7 Z06 production car. Like its predecessors, the C5-R and C6.R, the seventh generation racer was constructed and prepared by Pratt & Miller for Corvette Racing. The C7.R competed in the GTLM class of the newly formed TUDOR United SportsCar Championship, which was later renamed to the IMSA WeatherTech SportsCar Championship in 2016. The C7.R also met the the FIA/ACO GTE Pro class regulations making it eligible for any FIA World Endurance Championship events such as the 24 Hours of Le Mans. The inaugural 2014 season of the TUDOR United SportsCar Championship would also be the debut season for the Chevrolet Corvette C7.R.
The renamed Grand Touring Le Mans (GTLM) class carried across most of the same regulations from the previous GT class of the American Le Mans Series. With Corvette Racing collecting five years of data from running a GT2/GT specification C6.R, they were able to transfer a lot of the technology to the C7.R. Corvette Racing struggled for their first three years in the GT2/GT class with the C6.R, breaking up eight years of consecutive manufacturers titles. However, they were able to develop the C6.R GT to find success in 2012 and 2013, collecting back to back drivers and manufactures championships. The previous success resulted in the new C7.R immediately being competitive taking four class wins in its inaugural season and accomplishing a total of three drivers and manufacturers championships within its five seasons for Corvette Racing. The C7.R also made history in 2015 achieving the triple crown of endurance racing achieving class wins at the Rolex 24 at Daytona, the Twelve Hours of Sebring and the 24 Hours of Le Mans within the same year. The C7.R competed in its final season for Corvette Racing in 2019 before it was replaced in 2020 by the new mid-engined Corvette C8.R.
2013 was a huge year for General Motors and their legendary sports car. Not only was it the 60th Anniversary of Corvette but it was the same year GM unveiled the new seventh generation model Corvette. The C7 Corvette Stingray was the industry’s most awarded car of 2013, with technology transfer from the race team and a whole new design that shared only two components from the previous C6 model. Throughout 2013, Pratt & Miller focused most of their attention to developing and testing their new C7.R. Due to this, the 2012 chassis of C6GT-005 and C6GT-006 were used again for the 2013 ALMS season. For the motorsport world 2013 would be the final year of the American Le Mans Series after 15 years. Corvette Racing held the ALMS close to their hearts as the team was formed to compete in the series. Throughout their 15 years racing in the ALMS, Corvette Racing took part in 135 races, winning 82 of them. This resulted in nine drivers championships with seven consecutive and 10 manufacturer/team championships including eight consecutive. Those impressive results made Corvette Racing the most successful GT racing team in ALMS history. The 2013 season would also close the chapter for Corvette Racing and their C6.R model, which had awarded the team six championships throughout its eight year run.
Panoz Motorsports sold the American Le Mans Series to NASCAR Holdings, Inc in 2012. The ALMS operated under the International Motor Sports Association (IMSA) sanctioning body, whilst NASCAR Holdings, Inc ran the Grand-Am Road Racing sanctioning body of the Rolex Sports Car Series. It was announced on September 5th, 2012 that the new ownership would merge the two series to form the TUDOR United SportsCar Championship (TUSCC) for 2014. This created the opportunity for the first time since 2001, for Corvette Racing to compete at the Rolex 24 of Daytona. For the inaugural season of the TUSCC the organizers would change the name of the GT class to Grand Touring Le Mans (GTLM) due to carrying over the Grand Touring Daytona (GTD) class from the Grand-Am series. The GTD class used GT3 specification race cars, whilst the GTLM class used the same regulations from the Fédération Internationale de l’Automobile (FIA) designed for Le Mans. These regulations saw a small performance difference between the GTLM and the GTD class, with the GTLM cars producing a slightly higher power output and typically lower overall weight than the GTD field. The result of the regulations saw the GTLM cars running faster lap times than the GTD cars, separating the two GT style classes on the circuit.
The C7.R was built in conjunction with the new C7 Z06. Although unannounced during the development of the race car, the Z06 would be the most track-capable Corvette at the time. This would create the closest link in modern times between a Corvette race car and production car. The Z06 and C7.R would share unprecedented levels of engineering and components, which included chassis architecture, engine technology and aerodynamic strategies. US Vice president of Performance Vehicles and Motorsports – Jim Campbell, stated a lot of the Corvette production teams success came from the symbiotic relationship between Corvette Racing and the production vehicles. The C7 Z06 and C7.R were more competitive on the street and race track due to Corvette Stingray, which was heavily based on the C6.R race car.
The first images of the C7.R were released from the test sessions conducted at Sebring between December 9th – 10th, 2013. The test mule was dressed in a chequered style camouflage making it difficult to fully visualize the design cues of the new race car. Despite the camouflage the flared fenders, front splitter, rear wing and rear diffuser stood out easily. The C7.R made a public appearance at another test session known as ‘The Roar Before the 24’ that took place at Daytona between January 3rd – 5th, 2014. The ‘Roar Before the 24’ session allowed all teams competing at the Rolex 24 at Daytona to run their cars to collect data for upcoming race on January 25th-26th, 2014. Corvette Racing would run the C7.R at the test session yet again in the same camouflage wrap, but this time featured the red door numbers, rear wing end plates and window banner sections, which was the color selected to identify the GTLM class. The official unveiling of the C7.R was on January 13th, 2014 alongside the new C7 Z06 at the North American International Auto Show in Detroit. This allowed the public and media see for the first time the new livery of the C7.R, that carried over the tradition of a prominently yellow color scheme.
The new C7.R accomplished its first class win in only its third race at Long Beach. It would follow on by taking three more GTLM class wins at Laguna Seca, Watkins Glen and Bowenville, making it four consecutive class victories. At its first outing at the infamous 24 Hours of Le Mans, the C7.R came second in class, which was the first podium for Corvette Racing at Le Mans since their class victory in 2011. In its debut season the C7.R managed to finish third in the GTLM manufactures standings with Antonio Garcia finishing third in GTLM drivers standings.
The following year the C7.R was even more impressive by securing the triple crown of endurance racing, taking a class wins at the Rolex 24 of Daytona, the Twelve Hours of Sebring and the 24 Hours of Le Mans. Throughout the 2015 TUSCC Corvette Racing accomplished a combined total of six GTLM class podiums, including two wins. Despite the success early in the season Corvette Racing would finish third in GTLM manufacturers standings with Antonio Garcia and Jan Magnussen taking third in GTLM drivers standings.
The 2016 season would be the most successful year for the C7.R, collecting both the GTLM drivers title and manufacturers title. With new rules incorporated into the GTLM class similar to the GT3 specifications, the C7.R featured a much bigger aero package. With a larger front splitter, side skirts, rear diffuser and repositioned rear wing mounted further back, the C7.R benefited from the changes. The series took on a new sponsor creating a rename to the IMSA WeatherTech SportsCar Championship. Corvette Racing collected a combined total of 12 GTLM class podiums, which included five class wins and two 1 -2 finishes. A victory at Lime Rock sealed a milestone for Corvette Racing as it became their 100th win. The success of the team in 2016 handed Oliver Gavin and Tommy Milner the GTLM drivers championship, whilst securing Corvette Racing the GTLM manufacturers championship. The C7.R collected a total of three consecutive GTLM manufacturer championships between 2016 and 2018, with Antonio Garcia and Jan Magnussen taking the GTLM championship in 2017 and 2018.
The Corvette C7.R was retired by Corvette Racing at the end of the 2019 season as it was replaced by the new mid-engined C8.R for 2020. Within its five years competing for Corvette Racing the C7.R started 65 races winning 16 of them. Despite often being a victim of the Balance of Performance, the C7.R never finished lower than third in the GTLM manufacturers and drivers standings.
When it comes to the backbone of a Pratt & Miller Corvette, the rules have always required the production Corvette chassis to be used. The previous C5-R Corvette used the factory steel chassis with modifications made to accomodate the race suspension components. The GT1 C6.R used the steel chassis from the base model C6 Corvette, which incorporated minor modifications due to stricter rules introduced in 2005. The GT2/GT specification C6.R, became the first Pratt & Miller Corvette race car to use the stiffer aluminum frame of the production C6 Z06 and ZR1 variants. The aluminum frame posed new challenges for the fabrication team including welding a steel roll cage to it, but solutions were found throughout the production of the six race cars. The aluminum frame immediately impressed the team, with the drivers reporting high levels of mechanical grip and more predictability upon driving on the limit.
The production of the new C7.R became an evolution of the C6.R GT, keeping the tradition of using the production aluminum frame. However, for the first time, the chassis for the race car and production Z06 would be built in-house at the Corvette’s Bowling Green, KY., assembly plant. The seventh generation chassis used on the new Z06 would differ from its predecessor thanks to the advancement in manufacturing materials. The new production fabrication process utilized a GM-patented aluminum spot-welding process, flowdrill-machined fasteners and laser welding making the production structure significantly stronger. For the Corvette Racing team, the result of the new process was a race chassis that was 40% stronger on the C7.R than the one used previously on the C6.R.
Just like the previous models of Corvette race cars, minor modifications had to be made to the chassis. With bespoke fully adjustable race suspension equipped to the race car, the chassis required different suspension mountings. These mountings were designed to accommodate the wide race tires and large AP Racing brakes. Safety from day one had been a priority for Corvette Racing and throughout their 15 years racing, the safety equipment had seen many improvements. The steel roll cage welded to the chassis was specifically designed to protect the driver and absorb the energy of high speed impacts. With many hours spent designing the roll cage, calculations had been made for the position of each steel tube to send the energy of an impact away from the driver. Despite adding a lot of weight the roll cage makes up in the handling department due to the unique design, which increases the overall stiffness thus improving the overall mechanical grip.
Throughout initial testing of the C7.R the drivers immediately reported back their appreciation of the stiffer chassis. The stronger frame helped improve mechanical grip, due to lowering any chassis flex during corner transitioning. The lack of flex increased the contact of the all four tires, overall improving the drivers use of the friction circle. The new frame also made the attitude of the handling more predictable over rough track segments and changing surfaces. This was an important feature on the C7.R due to the diversity of race circuits in the Corvette Racing calendar. For example Sebring is notorious for its violent bumpy surface, due to the concrete tiles with large seams through turn one and 17. The race calendar also included street circuits like Long Beach and Le Mans that feature large portions of closed public roads. Even on a modern smooth track like the Circuit of the Americas, drivers don’t always stay on the flat pavement. Due to pushing the car to the limits, the drivers are constantly hitting steep curbing at corner apexes. After his seat time during the ‘Roar Before the 24’, Jan Magnussen reported that all the drivers had similar feedback; that the C7.R was a little bit easier to drive than the C6.R. This was due to it moving around less and the feedback from the stiffer chassis.
For 10 years Katech had been the engine developer for Corvette Racing. After the economic crash in 2008 that forced General Motors into a government bailout, GM were finding multiple ways to save money. This forced the GM Racing program to take a hit, but fortunately there was no plans to end the Corvette Racing program. Despite keeping the Corvette Racing program going, the team needed to find ways to cut back on expenses. The steep budget required for the GT1 class that Corvette Racing had previously competed in, died out by 2010 making the more cost effective GT2 class the highest form of GT endurance racing. Pratt & Miller constructed a GT2 specification C6.R for Corvette Racing, that started competing halfway through the 2009 ALMS season. Corvette Racing announced that for 2010 they would move to an in-house engine building operation. This move was made to further lower costs as in-house was far cheaper than paying a third party company like Katech. The in-house operation also benefited GM due to a more streamlined transfer of technology between the Corvette race car and production car.
For 2014 the same LS5.5-R engine from the previous C6.R was carried over into the new C7.R. GM decided to carry across the 5.5L power-plant after looking at the regulations. The FIA and the organizing entity of Le Mans, the Automobile Club de l’Ouest (ACO), mandated that GTE Pro cars with naturally aspirated motors could not exceed a displacement of 5.5 liters. The alternative is a forced induction motor such as turbocharging or supercharging that must meet a maximum displacement of 4.4 liters. Seeming the C7.R is based on the C7 Z06, building a race equivalent of the 650 hp LT4 from the production car, would mean attempting to reduce the 6.2 liter supercharged V8 to 4.4 liters. The engineers also looked at if a supercharged motor would be wise in endurance racing. Due to the high temperatures created by supercharged motors, there is a risk of heat soaking resulting in a reduction of power. A supercharger also adds more complex architecture, due to the pulleys, intercooler and a higher center of gravity. These reasons persuaded the engineers to stay with natural aspiration due to its reliability, efficiency and compact packaging. Carrying across the LS5.5-R from the C6.R also brought with it three years of data and research, meaning the team had the added confidence in the motors reliability and characteristics.
Despite being the same engine, the motor underwent changes for the new race car including a new name of LT5.5 to match the new small block V8 dubbed the LT1 found in the seventh generation Corvette. Throughout its three years in the C6.R GT, the LS5.5-R motor saw many improvements. The in-house development of the motor took place at the Wixom Performance Build Center, but the motor struggled during its 2010 debut season. Both C6.Rs suffering from engine failure at the 2010 Le Mans 24 Hours making for the first full team retirement at Le Mans in Corvette Racing history. This forced the engineers at Wixom to develop the LS5.5-R, leading to a perfect reliability record post thereafter. In 2012 regulation changes allowed the LS5.5-R to capitalize on performance improvements as well as evolutionary adaptations. These improvements included the twin 28.6mm air restrictors under the 2012 GT regulations to increase in size to 29.2mm, creating a bump in power. The biggest change saw the engineers at the Wixom Performance Build Center designing a new intake manifold. The result of the new manifold was an increase in power, improvement in driveability, better throttle response and fuel economy.
The LT5.5 motor of the C7.R was able to improve over its previous variant in the C6.R by taking advantage of direct-injection. Corvette Racing had previously used direct-injection on the LS7.R motor found in the GT1 specification C6.R. However, after moving to the GT2/GT class the rules were stricter forcing the team to use the same configuration as the production motor the LS5.5-R was based upon. Seeming no engine across the C6 Corvette range utilized direct-injection, Corvette Racing were forced to use sequential port fuel injection. This hindrance was partly what influenced GM to equip the new LT series small block V8s with direct-injection. Both the LT1 of the C7 Corvette Stingray and the supercharged LT4 in the C7 Z06 featured direct-injection, which permitted Corvette Racing to adapt the new LT5.5 to direct-injection fueling.
The advantage of direct-injection for the C7.R was the improved efficiency that played a major role for endurance racing. Corvette Racing Program Manager: Doug Fehan had always maintained the car that wins at Le Mans isn’t the fastest but the one that spends the least time in the pits. Corvette Racing saw direct-injection typically improve the fuel economy by three percent. Despite being a small increase, three percent could be enough to bypass one whole fuel stop during a 24 hour race, translating to a significant advantage in track position. Another case for direct-injection was that it offered more precise throttle control leading to the smallest change in the throttle position by the driver, delivering a more accurate response from the motor. This type of throttle precision is important in motorsports as a driver in most turns can not simply apply full throttle at the apex at risk of spinning the tires or even losing control. Instead most high level race drivers will gradually apply power upon corner exit. With a more precise throttle, the driver isn’t guessing or over/under applying power due to the lack of response.
In terms of the power output of the LT5.5, GM never officially released the specifications, but instead estimated a power output of 488 hp. The GTE Pro/GTLM class saw an average of 500 hp across its diverse field of cars such as; Ferrari, Porsche, Aston Martin and BMW. Some of the GTE Pro cars produced over 500 hp or under due to the Balance of Performance (BoP). For example the BMW M6 was equipped with a 4.4 liter twin turbo V8. The boost pressure was regulated by the FIA and ACO, allowing the BMW to produce a power output closer to 525 hp. This was permitted due to the larger size of the M6 and its body style being closer to a family sedan rather than a supercar like its competitors. Due to this disadvantage the BMW was allowed a higher power output, developed by higher boost pressure from the turbos. The increased power allowed the M6 to produce similar laptimes to the rest of the GTE Pro/GTLM field. The C7.R was one of the lower powered cars in the class, due to being penalized for its advantages in other areas such as, chassis architecture and balance. For this reason the FIA/ACO added air intake restrictors that lowered the performance ability of the LT5.5. Without these restrictions the LT5.5 would produce in excess of 750 hp, but for reliability, fuel economy and to meet the the regulations, the output of the LT5.5 was closer to 493 hp @ 6,900 rpm and 479 lb-ft @ 4,800 rpm. These performance figures fluctuated throughout each season due to the BoP adjustments made by the FIA/ACO. Depending on how competitive or how far off the pace the C7.R was compared to the rest of the field, the air restrictors could be adjusted to alter the power output.
Since 2004 Pratt & Miller have equipped their Corvette race cars with Xtrac sequential transmissions. The sequential transmission allowed the driver to keep their foot planted on the throttle whilst pulling the gear lever back to engage a higher gear. No clutch was required during the upshifts and a ignition interrupter would cut spark during the transition of gears to ensure there was no rev spike. To go down gears the clutch pedal was required to ensure an accurate smooth downshift and simple push forward on the gear lever engaged the lower gears. As much as this style of transmission was much faster and accurate than a traditional H-pattern style, human error still could be made, which translated into transmission wear and loss of time. It was still a physical job for the driver to change gear and required one hand to be removed from the steering wheel during each gear shift.
The more modern and expensive alternative was paddle operated shifters. These shifters had been equipped to the top class Le Man Prototype (LMP) race cars for over a decade, but due to their complexity, they were not permitted in the GT classes. After the economic crash in 2008, the FIA tried to create better ways for race teams to save money. Despite a paddle operated transmission being more expensive than its sequential counterpart, the argument was made that the lower wear and tear of a paddle operated transmission would save money for the teams in the long run. This led to the decision in 2011 for a rule change to permit GT race teams to equip paddle operated transmissions.
Pratt & Miller wasted no time to equip the C6.R with paddle shifters. After many hours testing to tune the spark and ignition cut including the speed matching downshifts, C6RGT-003 and C6RGT-004 were ready for the 2011 season. The new transmission was a success although C6RGT-003 suffered transmission failure at the 2011 ALMS season finale at the Petit Le Mans. For 2012, Pratt & Miller built the last two C6 race cars of chassis C6RGT-005 and C6RGT-006. Both cars underwent many upgrades to take advantage of new rules, which essentially made the GT class faster. The Wixom Performance Build Center improved the powertrain, which included a revised calibration of the Xtrac six-speed semi-automatic transmission. The advancements helped the overall functionality whilst allowing for better durability.
Pratt & Miller would carry over the same Xtrac 529-6, six-speed semi-automatic transmission to the C7.R. With the three years of data collected allowing for more improvements to be made within the electronics ensuring the transmission would be more durable and effective. With the C7.R equipped with an Xtrac transmission it would mark the 10th year Corvette Racing had trusted the British based company for their gearboxes and differentials. Xtrac components range across a diverse group of motorsport disciplines such as Formula 1, Le Mans, and the World Rally Championship, Xtrac can be considered the best race gearbox manufacturer in the world. This statement can be backed by the fact the most successful race cars and teams have won races and championships with Xtrac transmissions and differentials.
The Xtrac 529-6 transmission of the C7.R featured adjustable gear and final drive ratios. In other forms of GT racing such as the FIA GT World Challenge series, the regulations enforce closed gearboxes, requiring the gear ratios to be set by the FIA for the season. The GTE/GTLM regulations allowed for each gear size to be chosen by the engineers for each race weekend to suit the track conditions. This was especially useful for circuits like Le Mans that features long straights where GTE cars can exceed 180 mph. The Pratt & Miller engineers would equip larger gears to achieve the higher top speeds. At a circuit like Laguna Seca with its short straights, a GTE car averages a top speed of 145 mph. The engineers therefore would use smaller gear ratios that helped improve acceleration, at the cost of top speed. The FIA/ACO rules also allowed for adjustable final drive ratios. The final drive could assist the transmission by creating a more accessible adjustment to the acceleration or top speed, without the need to adjust each gear size within the transmission.
With a paddle operated transmission being controlled by electronics, Pratt & Miller would design a bespoke, ergonomic steering wheel for the C7.R, with the shifter paddles mounted on the back. The wheel featured six color coded buttons on both the right and left side including two rotary dials in the center. Other versions of the wheel would later appear on the Pratt & Miller Chevrolet Camaro GT4.R, with the center emblems altering to match the car the wheel was equipped to.
The production Corvette C7 Z06, the C7.R was based upon has a wheelbase measuring in at 106.7 in. (2,710 mm). That was a one inch increase over the previous C6 model, however, the overall length of the C7 was 1.3 inches longer than the C6 Z06 and ZR1. The height of the C7 had lowered to 48.6 in. (1,234 mm) from the 49.0 in. (1,245 mm) of the C6. Just like the predecessor the Z06 variant of the C7 was wider than the base model Corvette resulting in the C7 Z06 measuring in at 77.4 in. (1,966 mm) wide.
The regulations of the FIA and IMSA require GT race cars to use the same wheelbase as their production counterparts due to the use of the production chassis. GM take this rule into consideration when designing their latest generation of Corvette and work in conjunction with Pratt & Miller. When GM introduced the sixth generation Corvette they took advice from Pratt & Miller, which in the chassis department resulted in a longer wheelbase, but a shorter overall length. By decreasing the front and rear overhangs found on the C5 Corvette, the handling of the C6 was vastly improved. The same approach was taken by GM, when it came to the development of the C7 Corvette.
The C7.R race car and the production Z06 shared only two measurements. Both the race car and production car have the same wheelbase at 106.7 in. (2,720 mm), and an identical overall length of 177.9 in. (4,519 mm). The rest of the dimensions differed with the width of the C7.R coming in at 80.7 in. (2,049 mm) a whole 3.3 inches (83.8 mm) wider than the production Z06. The increased width of the C7.R was due to the wider axle track to accomodate large racing tires and fully adjustable race suspension. The height of the race car was much lower than the production car by 3.3 in. (83.8 mm). With the C7.R sitting at only 45.3 in. (1,150 mm) high, the lower height was designed to lower the center of gravity, decreasing body roll, and overall improved handling. The lower ride height of the race car came with other benefits such as producing less drag and lift. These were desirable results for circuits like Le Man made up of four long straights requiring high straight line speed and stability. The ride height, however is completely adjustable to cater to any race circuit. Bumpy tracks like Sebring often cause race cars to bottom out, therefore an increased ride height was often used.
The whole C7 range of Corvette was heavier than the previous C6 generation. The Corvette C6 Z06 was the lightest within the sixth generation range, weighing in at only 3,131 lbs (1,420 kg). The C7 Z06 was almost 400 lbs heavier than its predecessor weighing in at 3,524 lbs (1,598 kg). Weight plays a major role in motorsports as the more mass to move affects speed, braking ability and overall handling. This puts pressure on race teams to make their cars as light as possible for an edge on the competition. However within the history of motorsports, race cars became so lightweight that drivers safety was at risk. For this reason the FIA mandates that GTE Pro cars must weigh a minimum of 2,745 lbs (1,245 kg) including the driver and fluids. This regulation resulted in the previous C6.R GT and the C7.R to have matching weight in race trim.
Pratt & Miller found many ways to save weight on the C7.R. The glass of rear and side windows was replaced with polycarbonate and the whole body was constructing from carbon composite. Where major weight saving was created was in the cockpit. Compared to the production Z06 car no luxury or comfort component was carried over. The interior of the C7.R is purely business featuring only one bespoke carbon fiber race seat with a Willians six-point harness. The rest of the C7.R cockpit was limited to a rear view monitor, Bosch digital display, electrical components, lightweight A/C unit and safety equipment such as a roll cage and fire extinguisher. The roll cage added a lot of weight, but with the absence of luxuries such as sound deadening, insulation, power leather seats, carpet, roof lining and the entertainment system makes the C7.R tip the scales at only 2,447 lbs (1,110 kg). When the driver and fluids were added the C7.R met the FIA minimum weight restriction, making the C7.R a whole 1,077 lbs (488.5 kg) lighter than the production Z06.
The base model C7 Corvette Stingray took inspiration from the aerodynamic strategies of the previous Pratt & Miller C6.R race car. This included the forward-tilted radiator that worked in conjunction with the functional hood vents. Front-quarter panel vents and the rear transmission and differential cooling vents. The C7 Z06 equipped with the Z07 performance package took the aerodynamics to another level, including a front splitter inspired by the one found on the C7.R, side skirts and front brake cooling ducts integrated into the grille. A rear spoiler with a large Gurney flap/wickerbill was included in the Z07 performance package, which altogether resulted in the production Z06 generating the most downforce of any GM vehicle at the time. Corvette Chief engineer – Tadge Juechter, mentioned how they worked concurrently with Pratt & Miller to develop the aerodynamic packages for the Z06 and the C7.R. The same modeling software was used to test both cars, deriving in the wind-tunnel test results and data to be shared.
The aero package of the C7.R was designed to meet the FIA regulations. For 2011 the FIA relaxed the rules around the rear diffuser of the GT race cars. Pratt & Miller redesigned the new rear diffuser, which included a steeper angle, along with adding lower rear wheel cutouts. The redesigned diffuser along with rear wheel cutouts allowed for cleaner air flow under the rear of the car, creating a better use of the Bernoulli effect essentially sucking the rear of the car down. In 2012 the rules evolved further to allow the GT class to utilize an improved aero package. This included mounting the rear wing 75mm (2.9 inches) higher than the previous wing, moving it into the cleaner air for improved downforce levels.
In the inaugural 2014 season for the C7.R, the regulations from 2012 were still in effect, therefore the aero package of the C7.R was similar to C6RGT-005 and C6RGT-006. The Pratt & Miller engineers were able to add a slightly larger front splitter on the C7.R, which followed the contours of the C7 front facia. A larger front grille that opened lower down than the production Z06 grille helped feed air to the forward-tilted radiator, that worked coherently with the heat extracting waterfall hood design. A similar hood design had featured across all the previous Pratt & Miller Corvette race cars, as the design limits the heat from the radiator to circulate under the hood. The radiator inlet on the C7.R served a second function as it underwent a more intelligent design the resulted in smoother airflow to the rear wing. These aerodynamic designs creating more efficiency, which improved the handling and stability of the C7.R at high speed.
An area where the C7 Z06 and C7.R share aerodynamic strategies was the rear-brake cooling ducts. In the past, the previous Pratt & Miller Corvette race cars had utilized NACA (U.S. National Advisory Committee for Aeronautics) ducts. This style of air duct has been used in motorsports for decades due to its unique design creating a ram air style intake whilst maintaining low drag efficiency. Both the previous C5-R and C6.R featured NACA ducts located at the top of the rear bodywork that provided cooling to the rear brakes, differential and transaxle. The Pratt & Miller engineers tried to find ways to create cleaner airflow on the C7.R, which inspired the race car to share a similar rear-brake cooling duct design to the production C7 Z06. On the production car these openings are located on each side of the rear quarter panels but served only one function of providing cooling to the rear brakes. The ducts on the C7.R direct air to the rear brakes like the production car, however, they also provided cooling to the rear differential and transaxle. Although similar in style and location to the production car, the openings on the race car are larger and feature a split to create multiple functionality. For low drag races like Le Mans, the lower brake cooling section of the ducts could be covered to reduce drag resulting in an improved top speed. With Le Mans featuring long straights and the front brakes providing most of the stopping power, the rear brakes would cool enough between each braking zone, despite the lack of airflow.
2016 Aerodynamic Package Rule Change
In 2016 the FIA along with the organizing entity of the 24 Hours of Le Mans, the Automobile Club de l’Ouest (ACO), introduced new regulations for the GTE Pro class. The new rules would also come into effect for the GTLM class in IMSA due to the series adopting the FIA/ACO GTE Pro regulations. With the absence of the GT1 class since 2011, the GTE Pro class had become the highest form of GT racing. Despite being the top-level of GT cars, the GTE class shared almost identical performance specifications with lower tier of GT cars such as the GTD class in the IMSA series and the FIA GT3 series. This influenced the decision to create new rules translating to enhanced performance for GTE Pro/GTLM cars whilst improving the safety.
The most notable change in safety for the GTE Pro/GTLM class was the introduction of the FIA-mandated roof hatch. The hatch created better entry for safety workers to the driver if required. However, the main purpose of the roof hatch was an access point for an extraction device to be inserted into the cockpit that secured the driver’s head, neck and spine in the event of an injury. The seat also required adaptations for 2016 to meet higher structural performance requirements whilst incorporating larger side restraints. Corvette Racing has been a trendsetter within driver safety and head restraints had been part of the driver cell for years. In 2003 the team introduced the side-impact crash box, designed to help dissipate the force and energy of a driver’s side impact. The primary chassis structure of the C7 Z06 production car also served as a fundamental component within the C7.Rs crash system.
Along with improved safety, the new regulations introduced the opportunity for an increased power output within the GTE Pro/GTLM class of roughly 20 horsepower. The increase in power, however was dependent on the Balance of Performance (BoP) figures between the different manufacturers. The minimum weight limit of 2,745 lbs (1,245 kg) was also reduced by 15 kg (33 lbs). These two changes combined were designed to equate to around a two-second per lap decrease in time at the Circuit de la Sarthe of the Le Mans 24 Hours.
The new round of technical regulation for 2016 created additional freedom for manufacturers within the aerodynamic design of their GTE Pro cars. The front splitter of the 2016 specification C7.R was overall much larger, extending out further from the front bodywork. The new front splitter worked in conjunction with the flat floor and a new rear diffuser design. These are known as a volume opened areas, therefore the front splitter is not completely flat but features dimension. This is to manage and accelerate the air underneath the car, essentially sucking the car to the ground. Pratt & Miller also added canards/dive planes, to the sides of the front fascia, similar to the ones found on the 2012 – 2013 Corvette C6.R but much larger. These new aero pieces help force more air over the top of the car, pushing more downforce on to the front wheels, whilst also directing cleaner air flow around the sides. For high speed races such as the 24 Hours of Le Mans, Corvette Racing removed the canards to lower the drag. Added to either side of the front splitter were new stepped turning vanes or carbon fences. These turning vanes were designed to be vortex generators. When multiple vortices in parallel rotate in the same direction, they combined create one large vortex. On the C7.R these vortices are manipulated to flow down the sides of the car to create a gate of air that traps the air flowing beneath the car, restricting it from flowing out the sides.
The air that had been directed and accelerated beneath the car by the front splitter was managed by improved side skirts that had almost doubled in size for 2016. The new side skirts served three purposes with the first principal being a barrier for the air flowing below the car to spill out from the sides, which would foul the aerodynamic strategy of the floor design. Air escaping from under the car would generate lift creating a lack of stability. Extended the side skirts disrupted the natural path of the air, that wants to flow towards the air travelling over the car. Another function for the side skirts was they worked in conjunction with the new front splitter and front carbon fences. The vortices that have been generated from the front aero package was assisted by the side skirts by restricting any air from being sucked under the car, which would create unwanted lift. The final use of the side skirts was they utilized the side exit exhausts. With the exhausts integrated into the rocker panels of the C7.R, the side skirts took advantage of the exhaust gases pushing down on them thus creating a minor increase in downward pressure.
The final piece to the ground air flow of the 2016 C7.R was a new rear diffuser. For the previous two years the C7.R diffuser featured a completely flat design. To capitalize on the rule changes, the rear diffuser became three dimensional, resembling the one found on the C6.R from the GT1 era. The leading edge of the 2016 rear diffuser started at the rear axle centerline and expanded towards the rear of car creating one large venturi tunnel. Side plates were added to help channel the air more effectively along with six longitudinal fences. These fences created seven individual tunnels that increased in width from the outside edges towards the center of the diffuser. These tunnels were carefully designed to improve the efficiency of the air flow and direct it to specific areas of the rear of the car. The new dimensional shape of the rear diffuser helped accelerate the air, resulting in more rear downforce. The rear diffuser completed the aerodynamic floor design of the C7.R and ultimately controlled the desired venturi effect. This effect is created by the larger volume of air in the front that is directed strategically over and under the car by the front splitter. The air is then compressed beneath the car by the flat floor and side skirts. When the air is compressed, it accelerates towards the low pressure air of the rear diffuser where the air is able to expand before exiting. Due to the accelerated air beneath the car it decreases in pressure, which inversely increases the pressure above the car resulting in powerful levels of downforce.
The final adaptation to the 2016 regulations was the relocation of the rear wing. The wing of the 2016 C7.R maintained its shape and size but featured redesigned endplates. The regulations allowed the GTE Pro/GTLM cars to position the rear wing further back, which improved its efficiency and effectiveness. Pratt & Miller fabricated new rear wing mounts that extend past the rear fascia. The previous mounts were designed upwards, therefore the trailing edge of the rear wing was almost flush with the rear bodywork. The new mounts pushed the rear wing 15 cm (5.9 inches) rearwards, therefore the trailing edge of rear wing extended past the rear bodywork. The new location of the rear wing changed where the pressure of downforce was allocated. This effectively created downforce behind the car, applying more pressure across the whole rear end. This was an improvement over the previous rear wing used on the C7.R that mainly applied downforce to only the rear axle.
The end result of the 2016 regulation changes to the GTE Pro/GTLM class made the C7.R overall 1.4 seconds faster than the 2015 Corvette C7.R. Despite being quicker overall, at most of the IMSA WeatherTech SportsCar Championship circuits, the lap times between the 2015 and 2016 C7.R were very similar. However, at Le Mans where the regulations were designed to really come into effect, the 2016 C7.R ran a fastest lap time of 3:53.398. When compared to the 2015 C7.R fastest lap of 3:54.823, the 2016 specification C7.R was 1.425 seconds faster.
The drivers were also pleased with the changes made to the C7.R. Jan Magnussen reported back that the new 2016 specifications of the C7.R provided more grip making the car nicer to drive with the added downforce. Oliver Gavin mentioned how much the whole GTLM class of cars looked amazing. He thought it was great to see how the cars had been developed aero-wise, calling them sexy, aggressive and great for the fans to look at. Gavin also commented on how the regulations had made the GTLM cars a lot more fun to drive, taking them a great step forward.
After GM equipped Brembo carbon-ceramic brakes as standard on the Corvette C6 ZR1, they became an option on some of the other high performance GM vehicles. The C7 Z06 featured Brembo steel brake rotors, but when equipped with the optional Z07 performance package the brakes were upgraded to carbon-ceramics. Corvette Racing had used carbon-ceramic brakes on the Corvette C5-R and the GT1 variant C6.R. In 2009 Corvette Racing transitioned to the GT2 class where carbon-ceramic brakes were not permitted, forcing Pratt & Miller to equip steel brake rotors to the C6.R GT. Corvette Racing did have some previous experience with steel rotors in 1999 due to carbon-ceramics not being allowed in the GT2 class for the Rolex 24 at Daytona. Fortunately, a decade later, brake technology had come a long way with the initial testing impressing the team with the performance the steel rotors provided. Despite not producing the same absolute stopping power of carbon-ceramics, the strength, consistency and driver feel hit all their targets.
For the C7.R, Pratt & Miller continued their 11 year relationship with AP Racing. The British based company, AP Racing, had been at the forefront of developing the highest standard of race brakes for all disciplines of motorsports. Corvette Racing had five years of data with their AP Racing steel brakes, which were previously used on the C6.R GT. The team carried across the same brakes to the C7.R that were made up of 15.35 inch (389.9 mm) vented and grooved iron brake rotors on the front with 14 inch (355.6 mm) rotors on the rear. The six-piston AP Racing monoblock brake calipers were equipped to both the front and rear, that featured composite pads. The front brakes feature a quick release function so the pit crew could switch out worn rotors at the halfway mark at 24 hour endurance races like Le Mans and Daytona. The Corvette Racing pit crew could accomplish a full front brake rotor change within a 52 second pitstop.
The pedal box equipped to the C7.R featured two master brake cylinders that allowed the driver to alternate the pressure between the front and rear brakes. This is an important feature within motorsports as the driver can apply in excess of 105 kg (231 lbs) of pressure to the brake pedal. This pressure transfers a lot of load to the tires, which can cause lockup or alter the corner entry characteristics. Race cars commonly feature a knob/rotary dial mounted within easy reach of the driver that allows adjustment to the brake bias on the fly. A brake bias dial would either move more pressure to the front brakes or rear, which is accomplished via a spherical bearing within the pedal box that adjusts the force distribution between the front and rear master cylinder. The benefit of adjustable brake bias to the driver is that the corner entry can be changed. For example if suffering understeer under braking, adjusting the brake bias to the rear will create better car rotation, resulting in better turn in. In contrast if the car is too loose or unstable under braking, moving the bias to the front can tighten up the cars rotation. Where adjustable brake bias plays a role in endurance racing is when the fuel load burns away and the weight distribution of the car alters. Also changing weather conditions, which can be common amongst endurance races will require brake bias tuning. Typically races like the Rolex 24 at Daytona features rain during the night hours. Under wet conditions the driver will struggle to apply as much force to the front brakes without the risk of locking up the tires. The driver therefore can alter the brake bias to cater to the changing conditions.
The suspension of the production Corvette C7 Z06 was an evolution of the traditional transverse composite leaf springs matched with magnetic ride controlled dampers. This tried and tested suspension setup translated to the production Z06 producing lap times on par with exotic hypercars at some of the world’s most famous race circuits. At Virginia International Raceway the C7 Z06 equipped with the Z07 Performance Package accomplished a lap time of 2:41.32. Compared to the 2:43.10 of the 875 hp, $945,000 Porsche 918 Spyder, the Z06 established its serious track capability. Despite the impressive performance levels of the factory suspension, the race car would ditch it for a bespoke fully adjustable coil-over race suspension setup. Pratt & Miller had been using fully adjustable race suspension setups on the Corvette race cars since the beginning. The race suspension setup provided increased durability, complete tunability and easier replacement in case of damage or failure. The suspension package of the C7.R utilized coilovers that sat between short/long arm double wishbones, with fabricated steel upper and lower control arms including machined aluminum knuckles. The package of the race suspension required the Pratt & Miller engineers to modify the C7.R chassis to create strut assemblies and mountings.
The dampers equipped to the C7.R were supplied by Moton, which featured complete tunability such as, bump stop range, slow bump settings, fast bump settings, slow rebound settings and fast rebound settings. The full adjustability of the dampers opened options to the team within the control of how well the suspension responded to bumps on a track. On a circuit like Sebring with its violently bumpy surface, a lack of stability can be a byproduct of driving at high speed. The ability to fine tune the dampers to respond slower to the harsh surface created better contact between the tires and the ground. Well tuned dampers also provided the race driver the opportunity to maximises the full width of a race circuit including hitting the curbing/rumble strips on corner entry and exit at speed. The adjustability of the dampers allowed the driver to use the curbs with more aggression with a decreased risk of the car going light or bottoming out. The Moton race dampers were also extremely durable therefore they could handle the abuse of a 24 hour endurance race with low risk of failure.
The Eibach springs featured adjustable spring rates within the suspension architecture. These springs allowed Corvette Racing to tune the way the suspension responded to the track surface across the diverse type of circuits on the race calender. Softening the spring rates allowed for more weight transfer to the desired wheel, producing more grip. However, too much softness could create excessive weight distribution removing grip from inside tires. To create the best results the suspension on a race car suspension is stiff to keep the car flat through turns. The springs added with the stiff chassis of the C7.R, created high levels of mechanical grip. These springs were also designed to be very tough to withstand the harshness they endure within the motorsport environment.
The suspension of the C7.R also included fully adjustable toe, caster and camber angle settings allowing the team to adjust the positioning of the tires. These tuning options provided the opportunity for the team to capitalize on the tire contact patches, turn in response along with specific positioning to heat or maintain tire temperatures. This could alter the handling characteristics, along with the amount of tire wear produced. At long endurance races like Le Mans and Daytona, Corvette Racing typically attempted to double stint their tires. These tuning options played an integral role within the pit strategy creating more opportunity for the drivers to run on the same tires with reduced risk of traction loss or tire failure.
The C7.R was equipped with bespoke, heavy duty, fully adjustable sway bars. The sway bars also known as anti-roll bars could be tuned to a softer or stiffer settings, which made a significant difference to the amount of understeer or oversteer experienced. The sway bars altered the levels of grip by controlling the amount of transversal body roll throughout cornering. Softening the front sway bar, whilst stiffening the rear would provide more body roll to the front creating better car rotation, at the cost of oversteer. In contrast, stiffening the front and softening the rear sway bar would tighten the amount of rotation, thus creating more understeer. The C7.R featured stiff, low suspension that, when combined with its stiff chassis, could affect its handling in some cases. Therefore the sway bars played a major role in enabling body roll for increased grip, without compromising the efforts made to maintain the desired rigidity for the definitive utilization of the friction circle. The sway bars could also be adjusted by the team during pit stops. Access holes amongst the body work of the C7.R allowed a member of the pit crew to access a speed handle wrench to adjust the softness of the sway bar. The ability to make mid-race adjustments to the sway bars was fundamental within endurance racing due to the ever changing conditions. With the transition of day to night, the air and track temperatures change, which alters the way the tires respond and even the aerodynamics due to air density. Altering the tire pressures for the next round of pit stops could improve the handling but an adjustment to the sway bar could completely affect the grip performance. In some instances a driver may have been dissatisfied with the handling, such as the case during the 2016 Rolex 24 at Daytona. The #3 C7.R was suffering with understeer, therefore throughout the pit stops the crew made sway bar adjustments that eventually led to the satisfaction of the drivers.
The C7.R like its predecessor was popular with the drivers due to the high levels of mechanical grip the chassis and suspension produced. Despite the mechanical grip, the drivers and crew of Corvette Racing had to work with synergy to tune the suspension for each event. Without this team work the C7.R would have struggled to be as competitive as it was.
The 2014 inaugural year of the C7.R marked the 10 year anniversary between Corvette Racing and their tire partner Michelin. Previously between 1999 and 2003, Corvette Racing used Goodyear as their tire supplier. At the 2003 Le Mans 24 Hours, Corvette Racing witnessed a notable handicap from the Goodyears in comparison to the rival Prodrive Ferrari running on Michelins. Prodrive were able to double stint their tires equating to less time in pit lane and more time on track. In contrast, Corvette Racing were limited to changing their Goodyears at each pitstop forcing them to trail behind. To add insult to injury, the Michelins produced higher levels of grip making it almost impossible for the Corvette Racing to keep with the pace of Prodrive. The following year Corvette Racing dropped Goodyear as their tire supplier for Michelin with the partnership continuing to date. At the 2004 Le Mans 24 Hours, Corvette Racing running on the Michelins decreased their lap time by almost six seconds from the previous year. The relationship between Michelin and Corvette Racing helped produce a partnership with General Motors. The two companies have collaborated high performance tires for vehicles such as the Corvette C6 ZR1, the Cadillac CTS-V, and the Corvette C8 Stingray.
The C7.R used Michelin Pilot radials tires that met the regulations implemented by the FIA and ACO. These regulations restricted the size and compound of the tires, however each tire manufacturer constructs their own tires with a unique blend of particular materials and chemicals. The construction of the tire compound can improve the levels of adhesion and wear rate. Michelin are part of a selection of tire manufactures such as Falken Tire, Dunlop and Goodyear to name a few. Despite multiple tire manufacturers, Michelin have proven themselves as the clear pacesetter within endurance racing. At Le Mans, Michelin have displayed the capability of completing four or more ‘stints’ equating to around 440 miles (704 km). In comparison to a street tire that may not seem impressive, however a tire at Le Mans are running at an average speed of 135 mph (216 kph). The Audi R18 TDi was the overall winner of the 2011 Le Mans 24 Hours. It only required nine sets of Michelins that completed a total of 355 laps, a distance of 3,024 miles (4,838 km). One of the three Audi drivers, Benoit Tréluyer, completed 470 miles (752 km) on one set of Michelins. At Le Mans an average tire change can add an additional 30 seconds, sitting at a standstill on pit road. With the ability to quadruple stint a set of tires, it can save in total over 10 minutes throughout a 24 hour race. With Michelins proven endurance and performance, it is easy to see why a majority of the teams that make up the Le Mans grid choose the french tire manufacturer.
The GTE Pro teams have a choice of three slick tire compound of soft, medium and hard. These different compounds wear at different rates and perform differently depending on track temperatures. A colder track will benefit from the softer compound as it can generate higher levels of adhesion. In contrast a hotter circuit will cause the soft tire to overheat, resulting in lower adhesion levels and aggressive tire wear. The hard tire would typically be the choice for a hot circuit due to their higher optimum temperatures and lower wear rate. There is also two choices of grooved/treaded tires for a wet circuit. Michelin worked hard to develop the tread pattern and compound for a rain tire that had enhanced water-clearing capabilities along with good levels of grip. The ‘wet’ tire featured channels to move water out underneath itself, but still had large areas of smooth rubber to increase the contact patch. This tire would typically be used for a wet track with a small amount of standing water. For heavy rain the ‘full wet’ tire would be the choice as it featured many deep channels that disperse the standing water. Due to a more complex tread pattern there is less rubber in contact with the track resulting in lower grip, but the trade off is a much lower risk of hydroplaning.
The FIA mandates the GTE tire sizes be 300/33-R18 on the front and 310/41-R18 in the rear. These wide race tires protrude out from the the chassis as far as the rules will allow to increase the axle track for improved stability. The tires on the C7.R are mounted to six spoke, single center locking nut, BBS aluminum wheels. Corvette Racing have consistently used BBS as their wheel choice since 2006. In the GT1 era the wheels were constructed from magnesium, but the GT2 class that evolved into GTE/GTLM require an aluminum construction. This added sprung weight to the Corvette race car, adding an overall increase of 330 lbs in comparison to the previous GT1 C6.R.
The electronics of a modern day race car are very complex due to the multiple roles they play. The overall operations of the drivetrain and transmission plus the monitorization of the car is powered by the electronics. There are over 100 individual sensors in a modern GT race car that detect information and data such as tire pressure, oil pressure, tire temperature, gearbox temperature to even the amount of slip from each individual wheel. In the previous GT1 era the telemetry was relayed in real time to pit lane,allowing the team and technicians to study the status of the car. This information was very useful for the team to potentially foresee issues that could be resolved before becoming fatal, whilst also aiding the team with adjusting the race strategy. When Corvette Racing transitioned to the GT2 class in 2009, the FIA rules banned the use of real time telemetry in the response to help reduce the costs of motorsports. This rule required a member of the pit crew to plug a laptop into an outlet located in the A-pillar of the C6.R at each pitstop in order to upload the data from the previous stint. Later teams made the argument that the removal of real-time telemetry made motorsport more dangerous and expensive due to potentially missing a major component failure that could cause a major accident on track. The FIA and ACO agreed with the points raised and permitted the use of real-time, one-way telemetry.
The use of two-way telemetry, which allows the crew to calibrate settings of the car from the pits, is strictly prohibited. However, the FIA permits the use of one-way telemetry that generates a flow of data from the car to the team on pit road. Endurance racing is one of the few remaining disciplines of motorsport that allows for real-time telemetry. Most other forms of motorsports only feature spot-checking of all the vehicles variables, once a lap. The C7.R telemetry also provided a continuous flow of information to the driver via the onboard screens. If an issue arose, an alarm would be posted on the digital dashboard for the driver to respond to. One-way telemetry provided Corvette Racing with data such as how the motor was running, the fuel consumption rate, tire temperatures, aerodynamic load and even displayed any mechanical parts that may have been showing signs of stress. The Corvette Racing engineers could study the telemetry from pit road to make calculations for the race strategy or inform the driver of changes to be made from within the car such as the fuel mixture.
The fully digital Bosch DDU 8 dashboard of the C7.R replaced the factory gauge cluster of the C7 production car. This screen provided important information to driver thanks to the cars monitoring system. At the top of the screen was 10 LED rev lights that changed color sequentially from green, orange, to purple before all 10 lights would transition to red indicating the perfect shift point. When the pit limiter was engaged these LED rev lights illuminated in a steady green. The default screen of the digital display featured the speed in miles per hour in the top right with the fuel predict directly below. A large gear indicator sat centrally with the temperatures for all four tires at the top left. Below the tire temperature display was the fuel remaining in gallons and fuel consumption per lap. To the right and middle was the current lap time including the time lost or gained per lap. Below the lap time was a battery voltage display and at the bottom right was the alarm indicator, that highlighted issues from low oil pressure to components suffering high temperatures. The rest of the bottom of screen showed the current driver settings such as, traction control setting, yaw setting, engine map and the amount of laps completed within the current stint. To either side of the digital display was a pair of nine LED lights that sequentially lit up from bottom to top in blue indicating the amount of individual wheel slip from either rear tire under acceleration. The more of the LEDs illuminated, the more the wheels were spinning. The same LEDs would light up in red if either of the two front wheels locked up under braking.
Collision Avoidance System
To the right of the digital dashboard was a Intel monitor that displayed the rear camera view. The C7.R featured a fire wall behind the driver that completely blocked the drivers view through the rear window. This safety feature had been on all the previous Pratt & Miller Corvette race cars, however the rear view monitor first made its appearance on the C6.R in 2005. The C7.R competed in multi-class racing therefore typically four different classes of cars were on track at the same time. The C7.R raced in the fastest of the GT classes, however other classes featuring less restricted cars such as P2 (Prototype 2), DP (Daytona Prototype) and LMP1 (Le Mans Prototype 1) would share the same race track. These faster cars could be upto 30 seconds a lap quicker at circuits like Le Mans, with over 20 mph faster closing speeds. This required the drivers in the GT classes to constantly check their mirrors to ensure they did not block or even collide with a fast approaching car. Pratt & Miller along with Bosch developed a collision avoidance system for the C7.R to further assist the driver. This system registered cars closing in on the rear of the Corvette via arrows on the rear view monitor. If a car was slowly gaining on the C7.R a green chevron would appear on screen above that car. This chevron would change from green, orange to red depending on the closing speed, with red being quickly. This was a great visual reference for the driver to determine if the car gaining was a competitor or of a different classification that needed to be let by. Once a car had moved into the blind spots of the C7.R a flashing red arrow would appear on the monitor indicating which side the car was passing on. Integrated into the monitor was the meters the car was behind, displayed on the left and the seconds behind on the right. This system was revolutionary for multi-class racing and eventually became mandatory by the FIA.
Below the rear view camera monitor was a carbon fiber button box in replacement of the C7 production center stack. This button box featured a series of switches, buttons and rotary dials for easy access to the driver.
The top row of buttons, starting from the left:
- Two starter buttons – These buttons engaged the fuel prime and starter motor. They played more of a backup role to the start button located on the steering wheel.
- Neutral button – This button engaged neutral within the transmission, as the paddle shifters could only shift up or down the gears.
- Emergency button – Used incase of an emergency such as injury or control failure of any components within the car.
- Electrical override button – This allowed the driver to override the electrical system of the car within an emergency situation.
- Fuel reserve button – Used for low fuel situations. This button plays more of a backup role due to the C7.R featuring fully automated fuel reserve system.
The second row starting from the left, featuring rotary dials:
- Headlight dial – Turned the headlights on or off as well as the interior light to illuminate the cockpit for night racing.
- A/C dial – Controlled the amount of cold air blowing from the air conditioner. A hose connected to the drivers helmet fed the cool air.
- Wiper dial- This dial toggled the windshield wiper on or off.
- Steering dial – Controlled the power steering strength, allowing the driver to alter the power for more feedback from the front wheels or in contrast, more assistment if fatigue has set in at a long race.
- Function – For making adjustments if anything had faulted within the car.
The final row starting from the left:
- Master power switch – Allowing the driver to turn on or off all the electronic power to the car
- Dimmer rotary dial – Controlled the brightness of the screens and lights within the car for night racing.
- Page rotary dial – This allowed the driver to alternate between different information pages displayed on the digital dashboard.
- Fire button – Featuring a protective guard surrounding the button to avoid accidental depression, this button engaged the onboard fire extinguishers in case of fire.
- Brake bias adjustment dial – This dial allowed the driver to make on the fly adjustments to the amount of brake pressure distributed between the front and rear brakes.
Within five years the steering wheel mounted to a Pratt & Miller Corvette race car had advanced from a simple round design featuring three buttons, to a bespoke, 14 button design of the wheel equipped to the C7.R. Pratt & Miller designed the steering wheel for the C7.R, that was constructed from carbon fiber, with aluminum paddle shifters on the back. The wheel was designed for making the task of operating the C7.R easier for the driver. The ergonomic shape of the wheel featured a completely flat bottom, rubberized grips with the top of wheel removed to give a clear view to the digital dashboard. Strategically placed around the center of the wheel were 12 buttons and two rotary dials. These buttons were placed within easy reach of the drivers thumbs in an order of most frequently used.
The buttons from right side, top down:
- Flash headlight – Important for multi-class racing for warning cars of a slower class of your presence.
- Pit limiter – Held the speed of the C7.R to 37 mph or the restricted pit road speed.
- Stop – Shut off the motor, which is a rule for Le Mans that engines must be disabled once the car stops in the pit box.
- Traction control increase – Allowed the driver to increase the strength of the traction control enabled.
- Right turning signal – This is mandatory under the FIA/ACO rules, however is rarely used.
- Alarm clear – Removed any warnings raised on the digital dashboard display.
The two center rotary dials from right to left:
- Fuel map – This toggle switch was frequently used by the driver upon instruction from the engineers on pit road. It allowed the driver to make adjustments to the fuel mixture to adjust throttle settings, engine map or for fuel saving.
- Traction control – The traction control toggle switch was used to pick a specific traction control setting between one and 12.
The buttons from left side, top down:
- Radio – This button allowed the driver to communicate with the team, via a microphone located inside the helmet.
- Drink – Race driving is very physical within a high temperature cabin. The drink button shoots water into the drivers mouth via a tube connected to the helmet.
- Start – This button was used to start the car, used typically after a completed pit stop.
- Traction control decrease – Allowed the driver to decrease the traction control strength.
- Left turning signal – Engaged the left turning signal
- Reverse – This button engaged the reverse gear within the transmission as reverse could not be selected via the paddle shifters.
The electronics of the C7.R steering was complex. The paddle shifters (unlike previous lever operated sequential transmission) sent a signal to the transaxle to change gear, whilst simultaneously sending a signal to the engine to cut spark and fuel. Under down shifting, the left paddle controlled the downshift of the gearbox, along with precisely controlling the revolutions of the engine to speed match the lower gear that was about to be engaged.
Endurance racing requires driver changes during pit stops. This had to be done quickly not to add time to the pit stop, whilst also being safe ensuring the safety belts are connected including the drink and radio are linked to the drivers helmet. Despite GTE/GTLM cars featuring fully functional doors, the driver still needs to climb through portions of the roll cage to cramb into the tight bucket seat. For this reason, most race cars feature quick release steering wheels to open up more space for a driver to get in and out of the cockpit. Pratt & Miller incorporated a new design feature for the C7.R that created smoother, less stressful driver changes. The steering column was spring loaded therefore a release handle tilted the steering wheel to high position out of the way of the driver. Once the new driver climbed in, they would simply pull the wheel down back into position. This eliminated the need to the remove the steering wheel, making for more streamlined driver changes.
Within its four years competing in the GT2/GT class, Corvette Racing switched up the previous Corvette C6.R livery each year. The predominantly yellow with black accent color scheme remained, however the style of the graphics was a completely new design for each season.
For the C7.R, Corvette Racing carried over the traditional yellow color scheme that had been associated with Corvette Racing for 14 years. The new livery of the C7.R was a cleaner look compared to the last four liveries used on the C6.R. It was designed to highlight the accents and detail of the C7 Corvette. The main sponsor of Compuware that had been part of Corvette Racing since 2003 was no longer a partner of the team. The black accents consisted of the black wheels, stinger hood stripe with the new look Jake Skull, and a black rocker panels that started from the front splitter and gradually raised up the sides towards the rear fascia. A wide slanted silver stripe started behind the fender vents that ran straight down to the side skirts and featured a C7.R logo at the bottom.
The livery of the C7.R appeared to be more focused on maintaining a production Z06 look. For the first time on a Pratt & Miller Corvette race car, a fender emblem that featured the production car name was used. This was created by the fender vents featuring a decal of the new C7 Z06 logo located in the same space the emblem appeared on the production car. On top of the rear quarter panels, detailed stickers gave the illusion of the production C7 quarter panel vents, despite the C7.R not featuring them. The rear fascia even integrated the production C7 slim rear reflectors, that had no use nor requirement on the race track.
Due to the class color coding rules of the Tudor United SportsCar Championship, both the #3 and #4 C7.R featured side mirrors, window banner end sections and rear wing end plates in red. Besides the door numbers, the only way to differentiate between the two Pratt & Miller Corvettes was a white window banner used on the #3 car and the use of a black window banner for the #4 car.
Throughout its five years competing for Corvette Racing, the livery of the C7.R remained very similar with only minor modifications made to some of the graphics each season.
The American Le Mans Series (ALMS) ended along with the 2013 season. NASCAR Holdings, Inc merged IMSA and the Grand-Am series whilst adding a new sponsor to form the TUDOR United SportsCar Championship (TUSSC). The new series followed on with the same format as the ALMS, but introduced the legendary Rolex 24 at Daytona to the calendar as well as Daytona Prototype class. Due to a majority of the teams in the GTLM class (formerly known as the GT class) competing at the Le Mans 24 Hours, it was important for NASCAR Holdings, Inc to conform to the FIA/ACO rules for certain classes. Teams like Corvette Racing would not have the time nor resources to construct cars of different specifications in order to meet mixed regulations.
Typically the start of the season for Corvette Racing was in March for the Mobil 1 Twelve Hours of Sebring, but due to the Rolex 24 at Daytona, the first race for the C7.R would take place between January 25th – 26th, 2014. This left Pratt & Miller less time to develop and prepare the new C7.R for competition, therefore public testing started in December of 2013. The new Corvette C7.R was present at the ‘Roar Before the 24’ within the first weekend of 2014. This event played almost like a dress rehearsal for the Rolex 24 hour race, allowing all the teams competing to test and tune their cars across three days. The ‘Roar Before the 24’ provided Corvette Racing the opportunity to collect fundamental data on their new car, including its pace against the competition.
The official unveiling of the Corvette C7.R was on January 13th, 2014 alongside the new C7 Z06. This gave the media and public a look at the new race car out of the camouflage and in race trim. Race debuts for any car within motorsports is extremely challenging due to the lack of knowledge on the competitiveness and durability of the components. However, for a debut at a grueling 24 hour race, the C7.R would not be eased into its role as the successor for the C6.R. Corvette Racing qualified fourth and 11th with Oliver Gavin in the #4 car putting up the best lap time. An electrical issue sidelined the #3 car but the team were still optimistic with it being such a long race. During the race the new C7.R impressed with its outright pace, unfortunately gremlins caught up with the team. With less than three hours remaining in the race, the #4 car that was running second in class at the time was chasing down the class leading car. Tommy Milner noticed the gearbox temperature aggressively rising therefore he immediately took the #4 car to the garage. The team discovered the transmission bearing had failed resulting in the transmission being switched out within 30 minutes. The #4 car equipped with a new transmission rejoined the race to finish fifth in class. The #3 car managed to take the class lead after starting at the back of the grid within just six hours. Unfortunately engine cooling was an issue, which eventually led to the retirement of the #3 C7.R. Despite a disappointing result for the debut race of the C7.R, it was obvious the new Corvette was a quick race car. The team would take what they learnt from Daytona and improve the C7.R for the rest of the season.
The second race for C7.R was another big challenge as it was the Mobil 1 Twelve Hours of Sebring. This event, despite being half the distance of Daytona and Le Mans, had built a reputation for being one of the most punishing events for a race car and driver due to its notoriously bumpy track surface. Yet again the #4 car was able to outpace the #3 during qualifying, allowing the two C7.Rs to start 4th and 5th in class. The #4 C7.R was able to lead the GTLM class throughout the race on numerous occasions until two spins late in the race followed by issues with the engine with only 30 minutes remaining. These incidents put the #4 C7.R back into sixth in class where it would finish. The luck of the #3 car was no better either, with front bodywork damage caused by a collision with the BMW on the opening lap. Later in the race, the fuel pump of the #3 car started to struggle, which required replacement, dropping the #3 car down the order to eventually finish eighth in class. Sebring brought with it another disappointing finish for Corvette Racing, but the C7.R again showed its pace that included putting up the fastest lap in the GTLM class.
Round three of the 2014 TUSCC season took the team to Long Beach, California for a 100 minute race on the street circuit layout. The #3 car would put in the fastest qualifying time, handing the first class pole position for the C7.R, with the #4 starting fourth on the grid. The race for the #3 car was quite uneventful, with the C7.R leading all but one lap. This would eventually lead to the first class victory for the C7.R along with the first win for Corvette Racing in the new TUDOR United SportsCar Championship. The #4 car was able to gain a position early in the race and was gradually closing the gap on the car ahead to eventually run out of time. The #4 car would finish third in class putting both Corvettes on the podium for a historic moment.
Round four took the team north up the state of California to Mazda Raceway Laguna Seca. The #3 car yet again managed to clinch a class pole position, with the #4 car putting in its best time good enough for fourth on the grid. This time around it would not be as easy for the #3 C7.R, with the BMW Z4 GTE stayed within a second behind the Corvette. Jan Magnussen managed to lead all 42 laps of his stint, but was constantly under pressure from the BMW, forcing Magnussen to lock-up his brakes on a few occasions going into the famous Corkscrew. Despite the challenge posed by the BMW, the duo of Magnussen and Garcia held the lead to take the second straight win for the new C7.R. The #4 car of Oliver Gavin and Tommy Milner, struggled with working the rear tires more than the other cars in GTLM and they finished fifth in class.
The next event for Corvette Racing would be the big one for the C7.R, taking its first trip to France for the legendary 24 Hours of Le Mans. The last class win for Corvette Racing at Le Mans was in 2011, so the team was eager to debut their latest generation Corvette race car to the world and hopefully take the class victory. Due to the regulations of Le Mans designating number groups to specific classes, Corvette Racing would use #73 and #74 for the event. The #73 C7.R was able to set the second fastest qualifying time in the GTE Pro class, with the #74 taking fourth on the grid. The C7.R so far in its last two endurance races had suffered with reliability issues, which the team had hoped to eliminate for Le Mans. At the six hour mark of the race, Richard Westbrook in the #74 C7.R was leading the GTE Pro class by nearly 30 seconds. The #73 car driven by Jan Magnussen at the time was able to take first from the Ferrari within just 40 minutes of the race start. At the halfway point Tommy Milner in #74 car was hunting down the lead from the Aston Martin, whilst Jordan Taylor in the #73 was in fifth after the C7.R lost nearly two laps in the pits due to the valve stem that allowed the car to be raised on its air jacks had failed. With six hours to go the positions of the two Corvettes had changed. Antonio Garcia in the #73 car was in fourth chasing down the third placed Porsche. The valve stem issue, including two safety cars had split the Corvette away from the class leaders. The #74 C7.R had dropped to fifth in class due to a slipping alternator belt caused by oil from a transmission leak that required time in the pits. Despite the safety cars and valve stem issues, the #73 Corvette was able to fight its way to an impressive second place in class finish at its Le Mans debut. The #74 car lost eight laps repairing the transmission leak and alternator issue, placing them fourth in class by the time of the finish. Overall the C7.R was very impressive at Le Mans and showed it could be a class winner.
Corvette Racing returned to America for round seven of the TUSSC taking place at Watkins Glen International. This would be the first time for the team competing at the historic circuit located in the state of New York. Despite a lack of data at the track, the #3 car was able to qualify second fastest in class, with the #4 car taking seventh. The #3 car of Antonio Garcia and Jan Magnussen led 154 of the 185 laps completed by the GTLM class within the six hour race. The #3 car was able to take the class victory resulting in the third straight win for the duo in the TUDOR United SportsCar Championship. This win moved Garcia and Magnussen into first place in the GTLM drivers championship standings, which also placed Chevrolet at the top of the manufacturers standings. Oliver Gavin and Tommy Milner were running in second behind their teammate for most of the race until a stop and go penalty was handed to the #4 car within the last hour of the race. The race officials penalized the #4 car for unavoidable contact, resulting in a fourth place finish.
Round eight of the TUSSC was a two hour and 45 minute race at the popular Canadian circuit of Mosport. Antonio Garcia was able to qualify the #3 C7.R second in class, whilst the best efforts of the #4 car sealed fourth on the grid. After battling with the Viper of SRT Motorsports, the #3 C7.R took its fourth straight GTLM class victory, extending the lead in the championship standings. Oliver Gavin and Tommy Milner struggled in the #4 Corvette finishing seventh in class.
Round nine would be another first for Corvette Racing at the iconic Indianapolis Motor Speedway. Both Corvettes struggled to adapt to the circuit with the #3 car qualifying sixth in class and the #4 taking tenth. After a two hour and 45 minute race Magnussen and Garcia managed to get the #3 car upto a fourth place finish, whilst Gavin and Milner finished right behind in fifth.
For round ten of the TUSCC, the team headed to Elkhart Lake to compete at Road America. Corvette Racing had tested the C7.R at Road America due to its long straights producing good data for Le Mans. Unfortunately the race would be a tough one foe Corvette Racing with both cars being victims of bad luck. With the #3 C7.R of Magnussen and Garcia trying to build a lead in the drivers standings, they suffered a puncture early in the race that put them out of contention for a win. The #4 car of Oliver Gavin and Tommy Milner received a penalty for leaving pit lane whilst the exit was closed. Despite the penalty, Gavin was able to get the #4 up to fifth in class until a late-race incident with another GTLM car dropped them back down the order. The #3 C7.R would finish sixth in class with the #4 behind in seventh. Fortunately Garcia and Magnussen would retain the lead in the GTLM drivers standings and Chevrolet in the GTLM manufacturers standings, but the gap had been closed.
The eleventh round of the TUSSC 2014 season took place at Virginia International Raceway. Corvette Racing had a win and a podium in their last two visits to VIR, however they would struggle to keep with the pace of the class winning Risi Competizione Ferrari. The #3 C7.R completed 82 laps to finish seventh in class, whilst the #4 car was the stronger of the two Corvettes was forced off the track mid-race dropping them four laps behind. Gavin and Milner would complete 78 laps taking ninth in class. The seventh place of Magnussen and Garcia was enough to maintain the championship lead for both the drivers and manufacturers standings.
The second to final round of the 2014 season saw Corvette Racing return to the Circuit of The Americas located in Austin, Texas. Magnussen and Garcia held only a six point lead over Jonathan Bomarito and Kuno Wittmer of SRT Motorsports in the GTLM drivers standings. Jan Magnussen put in the best lap time for Corvette Racing, placing the #3 C7.R in seventh. Oliver Gavin struggled to keep the pace with the front runners qualifying the #4 C7.R in ninth. This was the least competitive the C7.R had been all season. The race would not be much better for the team with the #3 finishing in ninth and the #4 taking tenth. During the race weekend at COTA, the FIA World Endurance Championship would run a six hour race on the same day as the IMSA race. Corvette Racing decided to compete in both events, which required chassis C7RGT-001 to make its race debut. Tommy Milner along with brothers Jordan and Ricky Taylor were selected to run C7RGT-001 for the WEC race. C7RGT-001 would use #65 and wore a unique Michelin/Konica Minolta livery. Pratt & Miller struggled to get the C7.R dialed in to the track with C7RGT-001 finishing seventh in the GTE Pro class. The tough weekend in Austin dropped Magnussen and Garcia to second in the drivers standings by 22 points to Bomarito and Wittmer.
The season finale for 2014 would be at Road Atlanta for the 10 hour Petit Le Mans endurance race. After driving chassis C7RGT-001 at Austin, Tommy Milner prefered the softer chassis compared to chassis C7RGT-002 resulting in chassis C7RGT-001 to be used in the final race of 2014. Antonio Garcia qualified the #3 C7.R in sixth place, whilst Tommy Milner put the #4 Corvette in ninth. Throughout the race Oliver Gavin and Tommy Milner displayed their best performances of the year, leading the GTLM class on four different occasions to eventually finish fourth. The #3 Corvette managed to take the GTLM class lead early in the race with a triple stint from Garcia. Unfortunately after handing over to Jan Magnussen the #3 C7.R was involved in a pile up due to pit exit being closed. The left front of the #3 C7.R was badly damaged, which required repairs costing them four laps. This resulted in the #3 car finishing the Petit Le Mans eighth in the GTLM class. Garcia and Magnussen would finish as runners-up to Jonathan Bomarito and Kuno Wittmer of SRT Motorsports whilst Chevrolet would finish third in the GTLM Manufacturers standings.
The debut year of the C7.R was very impressive. The team worked out the issues early in the season and unfortunately a string of bad luck kept Corvette Racing from taking the drivers and manufacturers championship title in only its first year of competition. In total for 2014, Corvette Racing collected six podiums including four wins in the inaugural year of the C7.R. A lot of data and information was collected throughout the season allowing the team to capitalize on the foundations built for the next years to come.
The first Corvette C7.R constructed by Pratt & Miller to compete in the renamed Grand Touring Le Mans class of the TUDOR United SportsCar Championship. The C7.R was built to the specifications of the FIA/ACO GTE Pro regulations, that were adopted by IMSA for competition in the USA. Most of the components of the C7.R, such as brakes, suspension, transmission and the basic architecture of the engine was carried over from the previous C6.R GT. This gave Pratt & Miller an advantage going into the inaugural season, due to the ability to transfer the data collected over the last four years.
Where the C7.R was completely new was within its foundations. The C7.R was built in conjunction with the C7 Z06 production car featuring a new aluminum chassis that was 40% stronger than the previous generation Corvette. The new chassis had a wheelbase that was one inch longer than the sixth generation Corvette and an overall length increase of 1.5 inches. With the aero package being strictly limited by the FIA, the improved rigidity of the chassis gave the C7.R an advantage over the competition due to the improved mechanical grip.
The aerodynamics saw a complete overhaul compared to the sixth generation Corvette. Pratt & Miller construction the aero package to the specifications of the FIA, but were able to capitalize on the aerodynamic principles of the C7 bodywork. A new and improved front radiator inlet altered the air traveling over the car producing smoother airflow to the rear wing. The rear bodywork was cleaned up by replacing the previously used NACA ducts for vents relocated to the lower front sections of the quarter panels that resembled the production Z06 rear brake cooling ducts. The bodywork of the C7.R overall improved the effectiveness and efficiency of the rear wing increasing the downforce without exceeding the restrictions of the regulations on the location, height and size of the rear wing.
The engine was the LS5.5-R used in the C6.R for the previous three years, which was renamed to the LT5.5 for its evolution into the C7.R. The small block V8 was constructed from the original architecture of the GM LS7, but due to regulations, the displacement was limited to 5.5 liters. The introduction of direct injection to the new LT series of V8 used in the seventh generation Corvette, permitted Pratt & Miller to incorporate direct injection to the race motor. Direct injection improved the throttle response along with the fuel economy over the LS5.5-R. The fuel economy played a major factor within the C7.R as in the long endurance races, it could add additional laps to a fuel stint, ultimately resulting in a better opportunity for victory.
Chassis C7RGT-001 became the C7.R test mule for Corvette Racing, which ran a few public demo laps at Mazda Raceway Laguna Seca during the Monterey Motorsports Reunion on August 17th, 2013. Corvette Racing later ran C7RGT-001 for a two day test at Sebring International Raceway between December 9th-10th, 2013. C7RGT-001 was wrapped in a black and white checkered camouflage livery until its unveiling on January 13th, 2014 alongside the new C7 Z06 production car at the North American International Auto Show in Detroit.
The TUDOR United SportsCar Championship required teams to attend the ‘Roar Before the 24’ test weekend that took place between January 3rd-5th, 2014. Corvette Racing would need two of their new C7.Rs at the test at Daytona International Speedway in Florida then the same cars would need to be ready for Rolex 24 at Daytona race, two weeks later on January 25th-26th, 2014. The teams typically arrive at Daytona a few days before the race as the free practice sessions start on the Wednesday. This created a dilemma for Corvette Racing in regards to running a C7.R in Florida then display it in Detroit and sending it back back to Florida for the race within a 16 day timeframe. To resolve the issue, Pratt & Miller decided to build three chassis in 2014, with C7RGT-002 becoming the #4 car that would be at Daytona along with C7RGT-003 as the #3 car. This left chassis C7RGT-001 available to be used in Detroit for the North American International Auto Show.
Chassis C7RGT-001 spent most of 2014 at the Pratt & Miller factory in Michigan leaving chassis C7RGT-002 and C7RGT-003 for competition. On September 20th, 2014, the 12th round of the TUDOR United SportsCar Championship was at the Circuit of The Americas in Austin, Texas. On the same day before the TUSCC race, the FIA World Endurance Championship (WEC) were running a six hour race at the same circuit. Corvette Racing made the decision prior to the race weekend that they would run the C7.R in both the WEC race and the TUSCC race. This resulted in chassis C7RGT-001 to make its competitive debut for the WEC race. Tommy Milner along with the two brothers of Jordan and Ricky Taylor would make up the three drivers for the six hour WEC race. #65 was used for chassis C7RGT-001, however the team struggled to find pace at COTA in both the WEC race and TUSCC race with C7RGT-001 finishing seventh in the GTE Pro class and 24th overall.
Tommy Milner ran both C7RGT-001 and C7RGT-002 on the same day in Austin and had some interesting information to report back to the team. He prefered the softer chassis of C7RGT-001 over the chassis of C7RGT-002 that he felt was too stiff. For this reason the final race of the season at Road Atlanta for the Petit Le Mans, C7RGT-001 replaced C7RGT-002 as the #4 car. C7RGT-001 was able to finish fourth in class at the season finale, with Oliver Gavin happy with the chassis leading to the decision to use chassis C7RGT-001 for the full 2015 season.
For the 2015 season, little changes were made to chassis C7RGT-001. The same aero package used the year before was carried over as well as the mechanical components. However, the engineers at Pratt & Miller worked hard to optimize the cars setup including the damper and spring rates. With a whole year of racing completed with the C7.R, the Pratt & Miller engineers during the off season were able to analyze the data and improve the C7.R for the 2015 season. This provided a good baseline setup for the C7.R at each race to drive right off the trailer opening up more time for fine tuning on the track. One area that was addressed by Pratt & Miller for 2015 was the brake pedal feel that became the biggest complaint from the drivers during the inaugural season. The drivers reported a large dead zone in the brake pedal feel that made it difficult to judge accurate braking pressure. With race drivers trying to leave braking to the latest possibility whilst utilizing the trail braking technique (that requires brake pressure to be applied and slowly released all the way to the apex), confidence in the brake feel is essential. To combat this issue, Pratt & Miller went back to Michigan and looked at the problem, which required them to developed their own entirely new braking system. The drivers reported back that the new system was a massive improvement, especially to the consistency that played a major factor at the longer endurance races. Another area addressed in 2015 was better cooling within the rear of the car. By rerouting the cooling ducts to the rear differential, transaxle and the rear brakes, a better cooling balance was created ensuring the brakes were not overheated.
The changes for 2015 made to C7RGT-001 created better lap times than the previous year, resulting in three podiums including the GTE Pro class victory at the prestigious 24 Hours of Le Mans. The win at Le Mans became the eighth all time win for Corvette Racing at the event and still remains today as their last Le Mans victory.
At the end of the 2015 season C7RGT-001 was sold to Jun San Chen’s Team AAI of the Asian Le Mans Series. Chassis C7RGT-001 was entered under Team AAI into the GTE Am class for the 2016 Le Mans 24 Hours. Former Corvette Racing driver Johnny O’Connell alongside Oliver Bryant and Mark Patterson finished ninth in class and 39th overall.
The second C7.R chassis built by Pratt & Miller for Corvette Racing to compete in the 2014 TUDOR United SportsCar Championship. C7RGT-002 was a sister car to C7RGT-001 and built to the exact same specifications. C7RGT-002 made its first public appearance at the ‘Roar Before the 24’ test between January 3rd-5th, 2014 in Daytona, Florida.
Endurance racing had featured position lights on the sides of the race cars for decades. Typically three, color coded lights near the number board would illuminate to help the spectators easily identify the top three cars within each class. If a car was leading its class the top light would indicate this. If a car was second in class two lights would symbolize this. For third in class all three lights would illuminate, therefore if none of the lights were on those cars were out of the top three. This was an effective and simple method, however tracking any car out of the top three was very difficult. The TUDOR United SportsCar Championship would make tracking the position of each car easier by incorporating a digital number board on the side of each car. The digital number board would simply display the position of each car in its class by a number. Pratt & Miller decided to place the digital position board within the new small side windows behind the B-pillars to create better aesthetics of the C7.R.
C7RGT-002 was allocated the #4 for the TUSSC and #74 for the 24 Hours of Le Mans. In 2014, C7RGT-002 was driven by Oliver Gavin and Tommy Milner with Robin Liddell and Richard Westbrook added as a third driver for the endurance events. C7RGT-002 made its competitive race debut on January 25th-26th, 2014 at the Rolex 24 at Daytona. This was not only the first race for the C7.R but the first time for Corvette Racing returning to Daytona since 2001. C7RGT-002 was able to show great pace in its debut race, however whilst chasing down the class leading car, the transmission bearing failed, taking C7RGT-002 out of the race for 30 minutes with a gearbox change resulting in a fifth in class finish.
C7RGT-002 collected its first podium at round three of the TUSSC on April 12th, 2014 at Long Beach where it would finish third in class. Unfortunately this would be the only podium for C7RGT-002 in 2014. At round nine of the the 2014 TUSSC at the Circuit Of The Americas, chassis C7RGT-002 was driven by Oliver Gavin and Tommy Milner in a two hour race. Earlier in the same day the FIA World Endurance Championship ran a six hour race on the same circuit. Corvette Racing decided to enter a single C7.R into the WEC race driven by Tommy Milner, Jordan Taylor and Ricky Taylor. Due to C7RGT-001 and C7RGT-002 not being available for the WEC race, chassis C7RGT-001 made its competitive debut in the WEC six hour event. After Milner ran C7RGT-001 and C7RGT-002 back to back he noticed that C7RGT-001 had a softer chassis, which he prefered. This essentially retired C7RGT-002 from competing with Corvette Racing, with C7RGT-001 taking over for the final race in 2014 and for the full 2015 season.
After the preference of Tommy Milner, chassis C7RGT-002 was no longer required by Corvette Racing therefore was sold at the end of the 2014 season to Larbre Competition. Pratt & Miller started selling their used Corvette chassis to the French team in 2010, when Larbre Competition purchased chassis C6 RGT-001 then later chassis C6GT-003 in 2011. In the hands of Larbre Competition, the best result for C7RGT-002 was fourth in the GTE Am class at the 2014 Fuji Six Hours race in the WEC series. Larbre Competition loaned C7RGT-002 back to Corvette Racing for two rounds of the TUDOR United SportsCar Championship in 2015, due to chassis C7RGT-003 being involved in huge crash during qualifying at Le Mans. A mechanical failure throughout the Porsche Curves caused Jan Magnussen to lose control and damage C7RGT-003 beyond any immediate repair. Whilst chassis C7RGT-003 was being rebuilt by Pratt & Miller at the Michigan factory, C7RGT-002 was used for round six of the TUSSC for a six hour race at the Watkins Glen on June 28th, 2015. It was driven by Antonio Garcia and Jan Magnussen as the #3 car and finished fourth in the GTLM class. C7RGT-002 was used again by Corvette Racing at round seven of the TUSSC at the Canadian Tire Motorsport Park for a two hour and 45 minute race on July 12th, 2015. Garcia and Magnussen would accomplish a podium finish in the GTLM class before chassis C7RGT-002 was returned to Larbre Competition.
C7RGT-002 was raced by Larbre Competition between 2015 and 2017 and accomplished back to back podiums in the GTE Am class at the Six Hours of Silverstone on April 17th, 2016 and the WEC Six Hours of Spa-Francorchamps on May 7th, 2016. The podiums would continue after Le Mans at the Six Hours of Nürburgring on July 24th, 2016 and the Lone Star Le Mans race in Austin, Texas on September 17th, 2016.
The last race to date for chassis C7RGT-002, was the 24 Hours of Le Mans on June 18th, 2017. Larbre competition revealed a radical ‘Art car’ livery ahead of the Sunday test day at the Circuit de la Sarthe on June 6th, 2017. The paint scheme was named the ‘Human’ livery and was designed by street artist Ramzi Adek, a mutual friend of one of the Larbre Competition drivers, Romain Brandela. The livery featured Day-Glo paint that lit up in the dark against black backgrounds, with pop art style graphics. The main idea of Adek was to create a flow of strength and power to carry the drivers through the Le Mans week. Despite finishing 15th in the GTE Am class, C7RGT-002 certainly drew a lot of attention in its final outing.
The third C7.R built in 2014 by Pratt & Miller for Corvette Racing to compete in the TUDOR United SportsCar Championship and the Le Mans 24 Hours. C7RGT-003 was built to the exact same specifications as C7RGT-001 and C7RGT-002. Building a third chassis in the first year of competition was unusual for Pratt & Miller as typically in the past, only two new chassis were built each year. Chassis C7RGT-003 was constructed in response to chassis C7RGT-001 becoming the unveil car for the North American International Auto Show in Detroit on January 13th, 2014. Chassis C7RGT-003 became a necessity due to the requirement of two cars to run at the ‘Roar Before the 24’ test session between January 3rd-5th, 2014. With chassis C7RGT-001 required in Detroit on January 13th and the Rolex 24 at Daytona race taking place the following week on January 25th-26th, building a third chassis became the best resolution.
Chassis C7RGT-003 became the #3 car driven by Jan Magnussen and Antonio Garcia with Ryan Briscoe and Richard Westbrook added for the third driver roles at the endurance events. C7RGT-003 made its debut at the ‘Roar Before the 24’ in Daytona, Florida between January 3rd-5th, 2014. It would later then make its first competitive debut between January 25th-26th, 2014 at the Rolex 24 at Daytona. In its debut race C7RGT-003 showed its impressive pace, leading the GTLM from the back of grid within just six hours. Unfortunately at the halfway mark of the race, C7RGT-003 started suffering from cooling issues that could not be resolved that eventually led to its retirement from the race.
Despite the disappointing debut, C7RGT-003 was able to have a very successful inaugural season. In only its third race C7RGT-003 was able to bring home the first class victory for the C7.R at the Long Beach street circuit. This victory would lead to four straight TUDOR United SportsCar Championship class wins with a second place finish in the GTE Pro class at the 24 Hours of Le Mans inbetween. After the five back to back podiums, C7RGT-003 was able to lead both the TUSSC GTLM Drivers and GTLM Manufacturers standings for 2014. Due to the success of the C7.R, the Balance of Performance (BoP) would intervene resulting in Corvette Racing being held off the podium for the rest of the 2014 season. This would eventually place Jan Magnussen and Antonio Garcia as runner-ups in the drivers standings and Chevrolet/Corvette Racing finishing third in the manufacturers standings.
C7RGT-003 would also be used by Corvette Racing for the 2015 season. The livery for 2015 was almost identical to the one used previously, however the silver flashes behind the front fender vents acquired a chrome finish. During the off-season the Pratt & Miller engineers would make the same upgrades to C7RGT-003 as they did to C7RGT-001, which included the improved brake feel and increased cooling within the rear for the differential, transaxle and rear brakes. The upgrades along with a year of data collected on the C7.R would translate into further success for 2015. C7RGT-003 would impress at the season opener, taking the GTLM class win at the prestigious Rolex 24 at Daytona. The momentum would be carried into the second round of the season with C7RGT-003 taking another class victory at the historic Twelve Hours of Sebring. For round three of the 2015 TUSSC season at Long Beach, C7RGT-003 collected another podium with a third in class finish. The triple crown of endurance racing was in sight for Corvette Racing that included a win at Daytona, Sebring and Le Mans. Unfortunately during qualifying at Le Mans, C7RGT-003 suffered a mechanical failure in the Porsche curves that ended with Jan Magnussen crashing hard into the wall. The damage was beyond repairable at the track, that led to withdrawal of C7RGT-003 at the 2015 Le Mans 24 Hours. Fortunately C7RGT-001 would manage to win the GTE Pro class at Le Mans, handing Corvette Racing the endurance racing triple crown. After Le Mans, C7RGT-003 required a rebuild at the Pratt & Miller factory in Michigan, therefore it would miss two rounds of the 2015 TUSSC season. Corvette Racing would loan chassis C7RGT-002, that had previously been sold at the end of 2014 to Larbre Competition for the two rounds. After the rebuild C7RGT-003 was unable to get back onto the podium in 2015 resulting in Antonio Garcia and Jan Magnussen finishing third in the GTLM drivers standings and Corvette Racing taking third in the manufacturers standings.
C7RGT-003 would finish sixth in class at the Petit Le Mans on October 3rd, 2015, which would be its final competitive race. To date C7RGT-003 was recently sold for $850,000. With its impressive résumé of historic class wins along with being only one of seven C7.Rs ever built, it was quite a collectors item.
C7RGT-004 became the fourth chassis built by Pratt & Miller for Corvette Racing to compete in the new IMSA WeatherTech SportsCar Championship, formerly known as the TUDOR United SportsCar Championship. C7RGT-004 was also built to meet the specifications of the FIA and ACO to compete in the 24 Hours of Le Mans and any FIA World Endurance Championship events. Chassis C7RGT-004 was constructed in 2015 and started testing later the same year, which included the Daytona November Test.
For the upcoming 2016 season the FIA/ACO announced that the regulations of the GTE Pro class would evolve to make the highest class of GT racing faster and safer. Since the demise of the GTS/GT1 class in 2011, the GTE Pro class had become the highest level of GT racing. Despite being the elite GT class, GTE Pro shared a lot of performance specification with GT3/GTD cars creating a minor gap in performance within the multi-class racing format. The FIA/ACO decided to address the issue by freeing up some of the restriction placed on the GTE Pro class, especially around the aero package. A slight bump in power and decrease in weight (if required by the Balance of Performance) along with improved safety separated the GTE Pro cars from other GT classes. Due to IMSA adopting the FIA/ACO GTE Pro regulations for their Grand Touring Le Mans (GTLM) class, any team competing in the GTLM class would be eligible for FIA WEC events such as Le Mans.
The safety changes included a new mandatory roof hatch that gave track safety workers better access to the driver for an extraction device that protected the drivers head, neck and spine incase of an injury. Further safety improvements mandated the seat to meet higher structural performance requirements, which included larger side restraints.
The 2016 regulation changes created opportunity for teams to increase the power output by roughly 20 horsepower. The minimum weight requirement of 2,745 lbs (1,245 kg) could also be reduced by 15 kg (33 lbs) to 2,712 lbs (1,230 kg). These performance changes were dependant on the Balance of Performance, that altered between the different manufacturers.
The most notable change for 2016 was the aerodynamic package, with the FIA allowing additional freedom to the design. The 2016 regulations saw the C7.R receive more aggressive aero. The new front splitter increased in length, protruding further from the front fascia, increasing its effectiveness. Added to either side of the splitter were stepped turning vanes or carbon fences that generated vortices to travel down the side of the car that acted as a large air gates, restricting any air under the car from escaping. Added to the front bodywork was removable canards/dive planes that helped add additional front downforce by directing the cleaner air over the car. For low drag races such as Le Mans, these canards could be removed to help increase the top speed. The final new feature equipped to the front of C7RGT-004 was a pair of pitot tubes located just above the Corvette nose emblem. These tubes measured the air speed that generated more accurate and useful data for the team and drivers to use.
The side skirts of C7RGT-004 maintained the same production C7 Z06 shape but had been greatly increased in width. The new side skirts worked in conjunction with the flat floor design that utilized the front splitter and rear diffuser to create a Bernoulli effect. For the best results, the air beneath the car needs to be directed towards the rear diffuser. Any compromise to the underflow of the air would decrease the overall downforce. Air under the car can escape out from the sides as well as the air travelling over the car can spill underneath. To avoid fouling the aerodynamic floor design, the new extended side skirts on C7RGT-004 worked in three different ways. With the increased width and help from vortices generated from the front stepped turning vanes, the air travelling below the car was trapped under the car increasing the effectiveness of the diffuser. The air travelling over the car was restricted from spilling below the car, which would generate undesired lift. Finally the side exit exhausts, integrated into the rocker panels, took advantage of the increased side skirt width by utilizing the exhaust gases pushing down on them, which added a small increase in downward pressure.
The last upgrade in the floor design featured on C7RGT-004 was the new three dimensional rear diffuser. The diffuser featured on the C7.R in 2014 and 2015 started from the back of the rear wheel opening and was completely flat in design with no side-plates or fences. The 2016 regulations gave Pratt & Miller the opportunity to equip C7RGT-004 with a completely redesigned rear diffuser that resembled the one from the GT1 C6.R. The new diffuser started further back at the rear axle centerline and expanded upwards to the rear of the car with side-plates that created one large venturi tunnel. The addition of six fences/strakes created seven tunnels that increased in width from the outside edges. These seven tunnels were uniquely engineered to help extract the airflow from under the car. This feature allowed the floor design to generate downforce by compressing the air beneath the car, which resulted in the air accelerating towards the low pressure created by the rear diffuser. This effect decreases pressure under the car, that creates an increase in pressure over the car resulting in higher levels of downforce.
The final aerodynamic component affected by the 2016 regulations was the rear wing location. The 2014 and 2015 specification C7.R featured rear wing mounts that were vertical, positioning the trailing edge of the wing in line with the rear fascia. The new regulations permitted teams to mount the rear wing 15 cm (5.9 inches) further back, which altered the area of pressure applied by the wing. Pratt & Miller therefore would design new rear wing mounts that extended the position of the wing behind the rear fascia. This improved the downforce levels produced as the wing that applied pressure to the whole rear of the car opposed to the previous location that just applied pressure to the rear axle. These regulation changes resulted in a 1.4 second faster average lap time compared to the previous three C7.R chassis.
Pratt & Miller decided to relocate the fuel ports of C7RGT-004, moving them from the upper section of the rear quarter panels to within the small side windows behind the B-pillars. Being in a higher position it made connecting the fuel hose easier for the Corvette Racing pit crew, reducing time and risk of mistakes. The fuel port had adopting the area the digital number position boards used to obtain. Pratt & Miller would relocate the digital number position boards to the doors, below the side mirrors.
The livery of C7RGT-004 was very similar to the previous liveries used on the C7.R, however the Velocity Yellow changed slightly in tone due to the GM paint introduction for 2016 of Corvette Racing Yellow. The chrome finished flashes behind the fender vents had new graphics of a stars and stripes on silver design, with an added ‘Made In America’ caption below. The black stinger hood stripe, featuring a Jake Skull, extended across the whole top of the car to the rear. The changes were subtle but along with the aero package, they created a more aggressive look.
C7RGT-004 became the #4 car driven by Oliver Gavin and Tommy Milner with Marcel Fässler and Jordan Taylor added as third drivers for endurance events. C7RGT-004 was involved in a historic battle with C7RGT-005 at their debut race during the Rolex 24 at Daytona when Oliver Gavin in the #4 car crossed the finish line 0.34 seconds ahead of Antonio Garcia in the #3 car to take the GTLM class win. At round two of the IMSA WeatherTech SportsCar Championship, C7RGT-004 was able to take the GTLM class win at the Twelve Hours of Sebring. At the third round of the season at Long Beach, C7RGT-004 was able to maintain its impressive pace with a second in class finish. Unfortunately at Le Mans, whilst running fifth in class, C7RGT-004 was involved in a crash during the 17th hour of the race that resulted in its retirement. Upon returning to the USA, C7RGT-004 was able to get back to podium finishing second in class at Canadian Tire Motorsport Park, Mosport. The following race at Lime Rock Park, Oliver Gavin and Tommy Milner brought C7RGT-004 across the finish line for another GTLM victory, which would be extra special as it equated to the 100th win for Corvette Racing. C7RGT-004 would collect another class win at the next round at Road America, which would be its final victory for 2016, however, C7RGT-004 would collect another podium at the Petit Le Mans season finale. In total for 2016, C7RGT-004 racked up seven podiums including four wins, that gave Oliver Gavin and Tommy Milner the 2016 GTLM Drivers Championship and Corvette Racing the 2016 Teams’ Championship. This became the first title for the C7.R and the 11th overall championship for Corvette Racing.
For the 2017 season, C7RGT-004 was used for just one event. The livery would remain almost identical to the one used the previous year, however the silver flashes behind the fender vents now featured a fading stars and stripes design. At the ‘Roar Before the 24’ test that took place between January 6th-8th, 2017, a red flag was caused by C7RGT-004 halting the Sunday session. A fuel injector failure was the root cause behind sprayed gasoline within the engine bay. After the fuel made contact with a hot surface, a fire broke out. Marcel Fässler was behind the wheel at the time and was able to escape without injury. The fire was limited to only the engine bay, however, C7RGT-004 was sent back to the Pratt & Miller factory in Michigan for repairs. Unfortunately C7RGT-004 was unable to be restored in time for the Rolex 24 at Daytona set between January 28th-29th, 2017, therefore C7RGT-006 competed as its replacement.
Chassis C7RGT-004 spent the next year as a display car used at most IMSA race weekends and Chevrolet/Corvette promotional events. However, C7RGT-004 would compete again in 2018 at the 6 Hours of Shanghai FIA World Endurance Championship (WEC) race. This was the first time Corvette Racing had competed in Asia and was the first planned single entry effort from Corvette Racing since the ALMS round at Texas Motor Speedway on September 2nd, 2000. The Texas race was, at the time, the tenth race overall for Corvette Racing, and became their first ever class victory. C7RGT-004 was shipped to China wearing a unique ‘Redline’ livery of silver on black with red accents. The new livery was used to promote Chevrolet’s recently released Redline performance vehicles. The FIA WEC series used a different compound of Michelin tire compared to the tire Corvette Racing had been using in America. The race was set for November 18th, 2018, so the team tried to collect as much data as possible on the new tire during free practice. With the rest of the WEC GTE Pro field having spent the whole season running the new tire, the C7.R struggled to keep with their pace. Tommy Milner and Oliver Gavin completed the wet race in the #64 C7.R, finishing eighth in class and 17th overall.
Chassis C7RGT-004 would see action one last time at the ‘Super Sebring’ race weekend held between March 15th – 16th, 2019. The weekend was made up of a 1000 mile FIA World Endurance Championship race on the Friday and the IMSA Mobil 1 Twelve Hours of Sebring event held on the Saturday. For the FIA WEC Saturday race, C7RGT-004 would wear the #63 like Corvette Racing had used for Le Mans. Antonio Garcia, Jan Magnussen and Mike Rockenfeller were selected to run both races with chassis C7RGT-007 being used for the Saturday IMSA race. Garcia was able to qualify C7RGT-004 fifth fastest in the GTE Pro class out of 11 entrees. However during the race, C7RGT-007 lost time due to the drivers side door needing to be replaced on a couple of occasions along with a struggle for grip. The team were able to get as high as fourth in class but would finish the race in eighth.
C7RGT-005 was the fifth C7.R built by Pratt & Miller for Corvette Racing to compete in the IMSA WeatherTech SportsCar Championship and any FIA WEC events such as the 24 Hours of Le Mans. C7RGT-005 became the sister car of C7RGT-004 and was built to the exact same specifications. These specifications altered from the first three C7.R chassis built by Pratt & Miller due to the FIA/ACO 2016 regulation changes to the GTE Pro class.
With the new 2016 aero package, C7RGT-005 began testing in late 2015 including a Daytona test on November 18th, 2015. C7RGT-005 became the #3 car in IMSA events and #63 in WEC events making the drivers Antonio Garcia and Jan Magnussen with Mike Rockenfeller and Jordan Taylor in third driver roles for endurance events. C7RGT-005 shared the same livery as C7RGT-004 but used a white background on the Corvette front window banner to help the team better differentiate the two cars.
The 2016 inaugural year of C7RGT-005 started with a historic battle with C7RGT-004 in the last 15 minutes of the Rolex 24 at Daytona. With both cars swapping positions for first in the GTLM class, C7RGT-004 driven by Oliver Gavin at the time managed to cross the finish line 0.34 seconds ahead of Antonio Garcia in C7RGT-005. The podium of C7RGT-005 at its debut race would be the last for a while with the next coming seven races later at the Canadian Tire Motorsports Park, Mosport. The following race at Lime Rock Park, C7RGT-005 would finish second in class behind C7RGT-004 that collected the 100th win for Corvette Racing. Towards the end of the season, C7RGT-005 started to find more success taking its first class win at round eight of the IMSA WeatherTech SportsCar Championship at Virginia International Raceway. The victory was followed by a podium at the next round at the Circuit Of The Americas in Austin, Texas. In the season finale at the Petit Le Mans at Road Atlanta, C7RGT-005 finished fourth in class helping Corvette Racing accomplish their 11th Manufacturers/Teams Championship. Throughout 2016, C7RGT-005 would collect a total of five podiums and one class win.
For the 2017 season, C7RGT-005 would be used again and achieved better results compared to the previous year. At the second round of the 2017 season at the Twelve Hours of Sebring, C7RGT-005 took the GTLM class victory, earning Corvette Racing their third straight Sebring win and their 11th in total. C7RGT-005 would collect another class win at the Circuit Of The Americas for the fourth round of the season. The fifth race on the 2017 Corvette Racing calendar took the team to France for the 24 Hours of Le Mans. C7RGT-005 was involved in a nail biting battle in the GTE Pro class during the dying last minutes of the race. After C7RGT-005 lost time earlier in the race due to a puncture, the team were able to get C7RGT-005 back to the front of the class. During the final pitstop of the race, the team opted to fuel only whilst switching drivers to Jordan Taylor. The worn tires were to last 45 more minutes to the end of the race but Taylor was struggling for grip during the final 10 minutes of the race. With under six minutes remaining, Taylor was holding off the #97 Aston Martin Vantage driven by Johnny Adam. Whilst going into Arnage corner, the Aston would squeeze by but would out brake itself allowing Taylor to regain the class lead at the exit of the turn. On the second to final lap, Taylor locked up the brakes going into the second chicane of the Mulsanne straight, causing him to bounce over the gravel trap. Taylor maintained the lead after the incident but unfortunately picked up a slow puncture as a result to the gravel. At the end of the lap whilst exiting the Ford chicanes, the #97 Aston Martin was able to pass by the Corvette. The slow puncture on C7RGT-005 caused the tire to fully delaminate, forcing Taylor to crawl around the Circuit de la Sarthe for the final lap. The #67 Ford GT of Ford Chip Ganassi Racing UK was able to pass by resulting in Taylor bringing a battle scarred C7.R across the finish line third in class. As much as Corvette Racing was disappointed they were still happy with the podium and the display of their ‘never give up’ attitude.
Upon returning to the USA, C7RGT-005 was able to take third place at Watkins Glen, three back to back fourth place finishes and a class win at Virginia International Raceway. At the Petit Le Mans season finale at Road Atlanta, C7RGT-005 took second in class, which earnt Antonio Garcia and Jan Magnussen the 2017 GTLM Drivers Championship by 23 points over Bill Auberlen and Alexander Sims of BMW Team RLL. The success of C7RGT-005 in 2017 also handed Corvette Racing the GTLM Manufacturers Championship becoming the 12th title in total for Corvette Racing.
The 2017 Petit Le Mans became the final race for chassis C7RGT-005, with two new chassis prepared for the upcoming 2018 season.
C7RGT-006 became the sixth chassis built by Pratt & Miller for Corvette Racing to compete in the IMSA WeatherTech SportsCar Championship with eligibility for any FIA WEC events such as the 24 Hours of Le Mans. C7RGT-006 was built to the 2016 FIA/ACO GTE Pro regulations like C7RGT-004 and C7RGT-005 making it almost identical to the previous two chassis.
C7RGT-006 was prepared in 2016 but it spent most of the year at the Pratt & Miller factory as a spare car for Corvette Racing. On the final day of testing at the Roar Before the 24 on January 8th, 2017, C7RGT-004 was badly damaged by a fire in the engine compartment. C7RGT-004 was unable to be repaired in time for the race on January 28th-29th, 2017, which resulted in C7RGT-006 replacing C7RGT-004 for the 2017 Rolex 24 at Daytona and the rest of the season.
C7RGT-006 became the #4 car in the IMSA WeatherTech SportsCar Championship and the #64 car at FIA WEC events. C7RGT-006 was driven by Oliver Gavin and Tommy Milner with Marcel Fässler added as the third driver for endurance events. Throughout the first two races C7RGT-006 would struggled, however at the third round of the season at Long Beach, C7RGT-006 accomplished its first class victory. Unfortunately this would be the only podium throughout the 2017 season for C7RGT-006 with its average class finish position being sixth.
In 2018, C7RGT-006 was able to achieve better success for the season. The 2018 livery remained similar to the one used in 2017, however, the Jake Skull on the hood featured new patriotic graphics. The 2018 Jake Skull used a silver background with the right side of the skull filled in red with the Corvette emblem/eye colored in silver. The left side of the skull remained silver with the left side Corvette emblem/eye filled in blue with a single silver star. The teeth of the left side of the skull where made up by blue slashes.
The first podium of 2018 for C7RGT-006 would yet again be at Long Beach with a GTLM class win. Oliver Gavin and Tommy Milner would collect their second podium of the year at Canadian Tire Motorsport Park, Mosport with a third place finish behind the sister Corvette C7RGT-007. The next best result for C7RGT-006 was at Road America with a second place finish behind Ryan Briscoe and Richard Westbrook of Ford Chip Ganassi Racing. The final podium of the 2018 season for C7RGT-006 was at the Petit Le Mans for the season finale at Road Atlanta. Oliver Gavin, Tommy Milner and Marcel Fässler took second place in the GTLM class, which secured Corvette Racing the 2018 GTLM Manufacturers title becoming the 13th Team title in the program’s 20 year history. In total throughout the 2018 season, C7RGT-006 accomplished four podiums including the one win. The Petit Le Mans result moved Oliver Gavin and Tommy Milner up the 2018 GTLM Drivers standings to finish the season in third.
The 2019 season would be the final year of competition for C7RGT-006 and it would also be the final year Corvette Racing would run the C7.R. Pratt & Miller started developing the new mid-engined C8.R as the successor for the C7.R to debut the following year in 2020. The livery for 2019 became an evolution of the 2018 paint scheme, with everything remaining identical besides a faded stars and stripes on silver that ran across the roof. The graphics resembled the silver flashes behind the front fender vents. C7RGT-006 struggled at the first two races of the season with the first and only podium of 2019 for C7RGT-006 coming at Long Beach. Tommy Milner and Oliver Gavin would finish third behind the #3 sister C7.R of Jan Magnussen and Antonio Garcia. The final race for C7RGT-006 was on October 12th, 2019 at Road Atlanta for the Petit Le Mans. C7RGT-006 finished three laps behind the lead GTLM car of Risi Competizione to cross the finish line for the final time in seventh. The average finishing position for C7RGT-006 in 2019 was 7th with the sister car of C7RGT-007 achieving better success. Oliver Gavin finished eighth in the 2019 GTLM Drivers standings. With Tommy Milner missing a race due to a hand injury obtained in a crash at Watkins Glen, he finished 11th in the 2019 GTLM drivers standings. The #3 crew put Corvette Racing third in the 2019 GTLM Team’s standings with the #4 crew finishing eighth in the standings.
C7RGT-006 was unable to single handedly win a title and was off the pace in its final season with Corvette Racing. Despite the setbacks, C7RGT-006 was able to earn a total of six podiums including two GTLM class wins within its three year run.
C7RGT-007 was the seventh and final C7.R chassis built by Pratt & Miller for Corvette Racing. Constructed to the GTE Pro regulations set by the FIA/ACO, C7RGT-007 competed in the IMSA WeatherTech SportsCar Championship with eligibility for any FIA WEC events such as the 24 Hours of Le Mans. The specifications of C7RGT-007 were identical to the previous three chassis built by Pratt & Miller that capitalized on the GTE Pro rule adaptations set in 2016. Chassis C7RGT-007 was named by Corvette Racing, Steve Williams. This was in tribute to a great friend of Corvette Racing, Steve Williams that did some of the electronic work for the team. He sadly passed away in early 2017, with his funeral taking place in the early afternoon of the 2017 Rolex 24 at Daytona.
C7RGT-007 made its debut at the ‘Roar Before the 24’ three day test session set between January 5th-7th, 2018 at Daytona International Speedway. C7RGT-007 would become the #3 car driven by Jan Magnussen and Antonio Garcia with Mike Rockenfeller added as the third driver for endurance events. C7RGT-007 used an identical livery to the sister #4 car but was separated by using a contrasting white background on the Corvette window banner.
The first competitive race for C7RGT-007 would be the 2018 season opener at the Rolex 24 at Daytona. Jan Magnussen was able to put C7RGT-007 on pole during qualifying with class record lap of 1:42.779. Despite running a mistake-free race, the Corvettes could not keep the pace of the Ford GTs. The #67 Ford went on to win the GTLM class with the teammate in the #66 Ford taking second place. C7RGT-007 finished two laps behind the Ford GTs of Ford Chip Ganassi Racing, placing Corvette Racing on the final step of the GTLM class podium.
C7RGT-007 would be kept away from another podium until round four of the IMSA WeatherTech SportsCar Championship at Mid-Ohio. Magnussen and Garcia would battle hard to finish third in class behind the #912 Porsche of Porsche GT Team and the #25 BMW of BMW Team RLL. The next event on the 2018 Corvette Racing calendar would be the 24 Hours of Le Mans. After just missing out on the class win in the final minutes the previous year, Corvette Racing was looking for redemption. C7RGT-007 wearing #63 for Le Mans, along with the sister car was hit with a 10 kg (22 lbs) weight increase by the Balance of Performance. This made both C7.Rs 11 kg (24 lbs) heavier than they were the previous year at Le Mans. C7RGT-007 qualified better than the sister car taking ninth position within the 17 car GTE Pro field. During the first six hours of the race, Garcia was able to get the #63 C7.R as high as fifth in class. The C7RGT-007 would battle hard with the rest of the GTE Pro cars to finish the race in fourth one lap behind the third placed #68 Ford GT and second placed #91 Porsche 991 RSR. The C7.Rs just didn’t have the pace to keep with the GTE Pro class winning #92 Porsche 991 RSR, which finished two laps ahead of the #63 C7.R of Antonio Garcia, Jan Magnussen and Mike Rockenfeller.
Corvette Racing returned to the USA to resume the IMSA WeatherTech SportsCar Championship for the Sahlen’s Six Hours of The Glen. C7RGT-007 managed to finish the six hour race second in class behind Joey Hand and Dirk Müller in the #66 Ford GT. The following race at the Canadian Tire Motorsport Park, Mosport, C7RGT-007 took another second place in the GTLM class behind the sister #67 Ford GT driven by Ryan Briscoe and Richard Westbrook. The eighth round of the season took the team to Lime Rock Park where Garcia and Magnussen put C7RGT-007 on the GTLM podium for another second place finish. Round nine of the 2018 season took place at Road America, where C7RGT-007 would finish third in the GTLM class behind the #4 sister car of Oliver Gavin and Tommy Milner. For the tenth round of season, Virginia International Raceway would be the venue where C7RGT-007 would take another second place in the GTLM class behind the #67 Ford GT. The second to last race of the 2018 season, would be in California at the WeatherTech Raceway Laguna Seca. C7RGT-007 would collect another podium, finishing third in class behind the #912 Porsche 991 RSR and the #25 BMW M8 class winner. The season finale would be the traditional Petit Le Mans. C7RGT-007 qualified second in class and was running a good race. Unfortunately with less than three hour remaining in the 10 hour race, C7RGT-007 was involved in a crash that resulted in a five minute repair. C7RGT-007 would finish eighth in the GTLM class, but with the #4 sister car finishing in second the GTLM title was secured.
In its first year of competition, C7RGT-007 was able to accomplish eight podiums giving Antonio Garcia and Jan Magnussen a six point gap to secure the 2018 GTLM Drivers Championship. The consistency of C7RGT-007 would hand Corvette Racing the 2018 GTLM Team’s Championship, making for Corvette Racing’s 13th team’s/manufacturers championship.
C7RGT-007 would be used in 2019 for the final season of the C7.R, with Pratt & Miller developing the highly anticipated new mid-engined C8.R in preparation for the 2020 season. The Rolex 24 at Daytona would be the 2019 season opener with C7RGT-007 showing great pace by qualifying second fastest. After the race start, C7RGT-007 was able to take the GTLM lead with Magnussen behind the wheel for the first 90 minutes before contact was made in pit lane with the sister #4 car. The incident cost C7RGT-007 three laps, but with smart strategy in conjunction with the caution periods, the team got Garcia back into the class lead. Unfortunately at the halfway point of the race, an electrical issue that impacted the digital dashboard affected the telemetry to the pits, which included the fuel monitoring system. As a result, Garcia would run out of fuel on the back straight. The problem was resolved in pit lane, with Garcia handing driving duties over to Mike Rockenfeller. C7RGT-007 re-entered the race eighth in class and was able to make up positions whilst displaying great pace making for a promising end to the race. However, the torrential downpour would flood the track, forcing the race officials to wave the red flags that eventually ended the race two hours early. C7RGT-007 was sixth in class at the time of the red flag, which became the official result.
For the second race of the 2019 season, the team headed to central Florida for a ‘Super Sebring’ weekend. The weekend was made up of two races with the FIA World Endurance Championship running a 1000 mile race on the Friday and the Mobil 1 Twelve Hours of Sebring event running on the Saturday. Corvette Racing decided to compete in both races, bringing chassis C7RGT-004 back into competition. The last race for chassis C7RGT-004 was at the 6 Hours of Shanghai FIA World Endurance Championship (WEC) race in 2018. Antonio Garcia, Jan Magnussen and Mike Rockenfeller were selected to run both races. For the IMSA Twelve Hours of Sebring event, C7RGT-007 started from third in the GTLM class. Two patches of rain would mix up the track conditions, however the #3 car ran a flawless race, finishing third in class behind the #911 Porsche and #66 Ford GT.
For round three of the IMSA WeatherTech SportsCar Championship at Long Beach, C7RGT-007 collected another podium finishing second in class behind the #912 Porsche 991 RSR, with the sister #4 C7.R taking third. The next race on the 2019 calendar was round four at Mid-Ohio. C7RGT-007 achieved its third podium of the season with a back to back second place finish in the GTLM class with the #912 Porsche taking another win.
After Mid-Ohio, Corvette Racing headed to France for the 24 Hours of Le Mans. The 87th Edition of the 24 Hours of Le Mans would be the 20th consecutive appearance for Corvette Racing. The 2019 Le Mans would also be the final time Corvette Racing would run the C7.R at the iconic event. During qualifying, Antonio Garcia set the fastest lap time for Corvette Racing in C7RGT-007, putting the #63 car third fastest out of the 17 car GTE Pro field. During the race, C7RGT-007 was running at the front for 21 hours, but was caught up in three unlucky safety car periods along with a trip to the garage following a spin. The race would end with disappointment for Corvette Racing with the official results placing C7RGT-007 eighth in the GTE Pro class.
Upon returning to the USA, the next event would be a six hour race at Watkins Glen. C7RGT-007 accomplished a fourth consecutive podium in the IMSA WeatherTech SportsCar Championship. C7RGT-007 would finish only 0.452 seconds behind the class-winning #911 Porsche to take another second place finish in the GTLM class. The result moved Antonio Garcia and Jan Magnussen to within only one point out of the top spot in the 2019 GTLM drivers standings.
The next three races at Canadian Tire Motorsport Park, Lime Rock Park and Road America, C7RGT-007 was kept away from the podium with the best result being fourth place at Road America. The results pushed Antonio Garcia and Jan Magnussen down the GTLM drivers standings into fourth. There was still a lot of optimism amongst Corvette Racing as there was only a 19 point gap from Earl Bamabers and Laurens Vanthoor at the top of GTLM standing with three races remaining in the season.
At round 10 of the IMSA WeatherTech SportsCar Championship at Virginia International Raceway, C7RGT-007 was able to collect another podium, finishing third behind the two Porsches. Garcia and Magnussen moved into third place in the drivers standings, however, Bambers and Vanthoor had extended their lead by 21 points. Round 11, took the team back to California for a race at WeatherTech Raceway Laguna Seca. C7RGT-007 would accomplish its final podium for 2019 with another third in class finish behind the #24 BMW M8 GTE and the class winning #66 Ford GT. By keeping the Porsches off the podium the gap had been closed by 15 points heading into the season finale.
The last race to date for C7RGT-007 was the 2019 Motul Petit Le Mans. Corvette Racing decided to debut the new mid-engined C8.R during some display laps prior to the race. C7RGT-007 would struggle throughout qualifying with a lap time placing C7RGT-007 ninth on the GTLM grid. Corvette Racing would have a challenge ahead of them to try close out the C7.R era with a victory. The #3 crew would make some gambles with the strategy that resulted with C7RGT-007 making up positions at the expense of extra stops. C7RGT-007 was able to keep the pace of the two lead GTLM cars but due to the extra stops, a yellow flag was needed to get them within a chance to fight for the win. A yellow flag came out but was within the last 30 minutes of the race leaving not enough time for Corvette Racing to make a push. C7RGT-007 would finish fourth in its final race with Corvette Racing, which resulted in Antonio Garcia and Jan Magnussen finishing joint second place in the 2019 GTLM drivers standings with Patrick Pilet and Nick Tandy of Porsche GT Team. Earl Bamabers and Laurens Vanthoor in the #912 Porsche would win the 2019 GTLM drivers title by 13 points which simultaneously awarded Porsche GT Team the 2019 GTLM Teams Championship making Corvette Racing the runners-up.
C7RGT-007 accomplished six podiums throughout 2019. It wasn’t the send off for the C7.R Corvette Racing were hoping for, however the C7.R certainly didn’t retire without a fight. Despite going winless within its 24 races for Corvette Racing, C7RGT-007 collected 14 podiums in total with seven third place finishes and seven second place finishes. C7RGT-007 would retire from Corvette Racing with the 2018 championship sweep, a 58% podium ratio, and with zero retirements.
|Model:||Chevrolet Corvette C7.R|
|Body Style:||Two-door coupe hatchback|
|Layout:||Front engine, longitudinal powertrain placement|
|Driveline:||Rear wheel drive|
|Steering:||Power-assisted rack and pinion|
|Steering Column:||Production Corvette with tilt|
|Rear View Display:||Intel|
|Headlights:||Hella 15 Volts|
|Safety Equipment:||Willans six-point harness, drivers side crash box, window net, roll cage|
|Manufacturing Location:||Pratt & Miller, New Hudson, Michigan, USA|
|Displacement (cu in / cc):||335.2 / 5493|
|Engine V-angle:||90° cylinder angle|
|Valvetrain:||16-valve, pushrod with overhead titanium valves, two valves per cylinder|
|Air Intake Restrictor Size (mm / In):||29.1 / 1.15|
|Bore (mm / In):||103.89 / 4.090|
|Stroke (mm / In):||80.90 / 3.185|
|Cylinder Case Material:||Aluminum|
|Cylinder Head Material:||Aluminum, CNC Ported|
|Throttle Systems:||Individual runners with carbon fiber proprietary butterflies|
|Fuel:||VP Racing Fuel|
|Fuel Delivery:||Kinser sequential multi-point electronic direct fuel injection|
|Lubrication:||Mobil 1, Dry Sump|
|Horsepower (hp / kW @rpm):||493 / 367.6 @ 6,900|
|Torque (lb ft / Nm @ rpm):||479 / 649 @ 4,800|
|Transmission:||Xtrac 529-6 six-speed semi-automatic sequential|
|Clutch:||AP Racing Multi-plate carbon fiber|
|Differential:||AP Racing adjustable mechanical limited-slip differential|
|Front:||Moton independent, short/long double wishbone, fabricated steel upper & lower control arms, machined aluminum knuckles, coil-over multi-adjustable shock absorbers, anti-roll bar|
|Rear:||Moton independent, short/long double wishbone, fabricated steel upper & lower control arms, machined aluminum knuckles, coil-over multi-adjustable shock absorbers, anti-roll bar|
|Shock Absorber Kits:||Moton|
|Front Rotors (in / mm):||Steel vented and slotted (15.35 / 389.9)|
|Rear Rotors (in / mm):||Steel vented and slotted (14.0 / 355.6)|
|Front Calipers:||AP Racing six-piston monoblock with composite pads|
|Rear Calipers:||AP Racing six-piston monoblock with composite pads|
|Brake Fluid:||Mobil 1 DOT 4|
|Tire:||Michelin Pilot Radial|
|Tire Compound:||Soft, Medium, Hard, Wet and Full Wet|
|Wheels:||BBS aluminum, single center locking wheel nut|
|Front wheel size (Inches):||12.5 x 18|
|Rear wheel size (Inches):||13 x 18|
|Front tire size:||300 / 32 – R18|
|Rear wheel size:||310 / 41 – R18|
|Wheelbase (in / mm):||106.7 / 2,720||106.7 / 2,720|
|Overall length (in / mm):||177.9 / 4,519||186.95 / 4,691|
|Overall width (in / mm):||80.7 / 2,049||80.7 / 2,049|
|Overall height (in / mm):||45.3 / 1,150||45.3 / 1,150|
|Weight (lbs / kg):||2,447 / 1,110||2,447 / 1,110|
|Fuel Capacity (gal / liter):||26.4 / 120||26.4 / 120|
|Wing Chord (in / mm):||11.81 / 300||11.81 / 300|
|Splitter (in / mm):||1.0 / 25||3.15 / 80|