The Chevrolet Corvette C6.R was the race-going equivalent version of the Chevrolet Corvette C6 Z06. The C6.R was constructed by Pratt & Miller and ran by Corvette Racing to compete in the American Le Mans Series and the 24 Hours of Le Mans. The C6.R was originally built to specifications for the production-based GTS class that was renamed to GT1 in 2005. A new variant of the C6.R was built in 2009 for the GT2 class due to lack of competition in GT1. The C6.R would continue the success of its predecessor the C5-R.
The development of the C6.R was built upon the experience gained from the C5-R including the advancements of the new-generation Corvette C6 and Z06 production models. After a full year of rigorous testing and development the new race car would become the most technically advanced sports car ever built by General Motors in association with Pratt & Miller.
The all new C6.R was officially unveiled at the North American International Auto Show in Detroit on January 10th 2005 alongside the new Chevrolet Corvette (C6) Z06. General Motors Vice Chairman Bob Lutz introduced the C6.R with Corvette Racing driver Ron Fellows pulling it onto stage. The success of the C5-R left big shoes for Pratt & Miller to fill when it came to the C6.R. In the five years the C5-R was ran by Corvette Racing, it had accomplished 35 class wins, an overall win at Daytona, three class wins at Le Mans and four ALMS manufactures championships. In the C5-Rs final season with Corvette Racing in 2004, it went undefeated.
Unlike the C5 Corvette, Pratt & Miller was able to give input to General Motors on the development of the new sixth generation Corvette. Pratt & Miller requested the C6 must have a front mounted radiator grille, fixed, exposed headlights and better aerodynamics. With the C5-R Pratt & Miller had to add grilles to the front of the car and construct their own frog eyed headlight covers, which created drag and made cooling of the race car difficult. Thanks to the new design of the C6, Pratt & Miller were able to construct the C6.R with little modifications to the original aesthetic design. These requests motivated the elimination of the pop-up headlights on the production Corvette for the first time since they made their introduction on the 1963 C2 Corvette Stingray.
The bodywork of the C6.R was designed to resemble the Z06 performance model Corvette. The Z06 design ques started with the front grille being wider and more square. Above the grille was a faux scoop behind the emblem, miminiking the Z06 scoop. The fenders were designed from the Z06 fenders, which were wider and featured a deeper fender duct. Finally fake quarter panel brake ducts where incorporated on the race car to resemble the ones found on the Z06.
The previous C5-R was built upon production roots and the C6.R would follow the same foundations. With this in-mind the GM engineers constructed the C6 production Corvette with a shorter overall length but a longer wheelbase, creating better stability and greater overall handling. The structure of the race car was built upon the same hydroformed steel frame rails that came off the assembly line at the Corvette plant in Bowling Green, Kentucky.
Another flaw of the C5-R that the C6.R would improve upon was the aerodynamics. The Circuit de la Sarthe the 24 Hours of Le Mans is ran on features long straights with the fastest being the infamous Mulsanne Straight. The C5-R would struggle to break 180 mph (290 kph) on this straight making it vulnerable to the competition that were achieving much higher speeds. The new body of the C6 worked better in conjunction with the aero package of the rear wing, front splitter and rear diffuser of the C6.R that achieved a better lift-to-drag ratio than the previous C5-R. Through a combination of CFD (Computational Fluid Dynamic) studies and the on-track testing, the C6.R featured an aerodynamically balanced package. The Corvette Racing calendar demanded a balanced aero package due to featuring a diverse range of circuits such as the fast flowing circuits like Mosport, high downforce circuits such as Leguna Seca and the low drag demands of Le Mans.
Under the hood of the C6.R sat the new LS7.R motor, which like the LS1.R found in the C5-R, was developed by Katech. The new seven litre small-block V8 featured CNC ported cylinder heads, titanium valves and connecting rods, a forged steel crankshaft, and plate-honed cylinder bores. The LS7.R would become one of the most successful race engines collecting multiple awards.
The original plan for Pratt & Miller was to take the last C5-R chassis, stretch its wheelbase by 1.2 inches and simply rebody it with the new C6 panels. This is what lead to chassis C5R-012 being built as the test car for the new C6.R bodywork. However the governing body, the Federation Internationale de l’Automobile (FIA) changed the rules of the GTS class in 2005. The class was renamed to GT1 and featured stricter production based guidelines, such as a greater portion of the original factory structure must be used in the construction of the race car. However a more open rule for engine modifications was created but still required an approximately 600 hp cap on the power output.
The rule changes forced Pratt & Miller to construct the new C6.R using large portions of the factory C6 uniframe for the primary structure. This included most of the production hydroformed frame rails, which differed from the late C5-R frames that had almost completely gone away from its production roots. Incorporated into the C6.R tubular space frame was the original factory frame rails, rear bumper beams and windshield frame. Due to the well designed production car components they didn’t give up any rigidity nor increased any weight over the earlier structures that was tested previous to the rule changes.
A roll cage was welded to the frame, which added more rigidity whilst greatly increasing the safety for the driver. A lot of the production suspension components was carried over, but subtle modifications was made to the frame to accommodate the fully adjustable race suspension.
The all new LS7 motor found in the Corvette C6 Z06 was used for the construction of the race motor. Katech was yet again selected to build the engine with GM Racing engineer Roger Allen being responsible for the design of the LS7.R. Thanks to the more flexible engine rules the GT1 class allowed for, the LS7.R shared components of the production GM Gen IV small block V8 but became a truly dedicated race engine. The aluminum block and cylinder heads were really all that resembled the production components, but even they had been modified. This included changes to the valve angle of the head’s, which had been decreased from 15 degrees to 12 degrees. Unlike the iron liners found on the production cylinders, the LS7.R big-bore cylinders were coated in nickel seal and featured shortened block skirts. The lower end of the motor featured a supportive lower crankcase that formed a collocation pan for the dry-sump oiling system.
The LS7.R would continue to use a displacement of 7.0 Liters with the bore being 4.1800 inches and the stroke 3.875 inches. The engine was forced to breathe through FIA-mandated air restrictors, that limited the GT1 engines power and RPM. These restrictors were not one size fits all but tailored to each car eligible for the GT1 class to ensure no car had an unfair advantage. Katech worked around the air restrictors with an innovative cross-ram intake manifold, with individual air intakes for all eight cylinders. The intake housing was narrow and topped with a single fuel rail, which stood over the block valley cover on tall carbon fiber runners. The result of this was utilizing a lower RPM range that maximized low-end torque and increased fuel economy, .
The carbon fiber airbox used two large plenums that contained filters and took air in from a pair of K&N cone shaped air filters that were located ahead of the air restrictors. Due to the restrictors the LS7.R ran out of air at about 5,400 RPM, where it produced its peak power of 590 hp, however the impressive torque figure of 640 lb ft came in at 4,400 RPM. Without the restrictors, the LS7.R has a rev limit of 8,000 RPM and Katech estimate the power would exceed 800 hp.
The previous C5-R, spent most of its Corvette Racing career using a Hewland H-pattern race transmission. However in the last season with Corvette Racing in 2004, the C5-R was equipped with an Xtrac six-speed sequential, that created a significant performance increase. Pratt & Miller would continue their relationship with Xtrac therefore a six-speed sequential transmission was also used in the C6.R.
Xtrac had solidified themselves as the transmission to use in top level motorsport. The British based company had been supplying race transmissions across diverse disciplines of motorsports for years and had built a reputation for performance and reliability.
Paddle shifters had been used on the LMP1 cars for a while by 2005 but the FIA did not permit them on the GT cars. The sequential gearboxes at the time were next best thing to a paddle shift transmission as they allowed for very accurate and fast gear changes. The driver did not need use the clutch pedal on upshifts and an ignition interrupter would electronically cut the spark to the engine during a gear change. This removed the need of the driver to lift their foot from the throttle pedal as the ignition interrupter deleted the rev spike that could happen during a gear change under wide open throttle.
The C6.R race car and C6 Z06 production car share the same wheelbase of 105.7 inches (2,685 mm), however the C6.R vastly differs from the production car in other areas. The ride height of the C6.R sits 3.2 inches (81.3mm) lower than the Z06. Dropping the ride height lowers the center of gravity allows for better distribution of grip over each tire under high g-force transitions. This greatly increases the handling and stability. It is important to note that the ride height of the C6.R is adjustable to cater for diverse circuit layouts. Even with this taken into consideration, the C6.R at its highest setting is still considerably lower then the production car.
The race car sits 2.8 inches (71.12 mm) wider than the Z06, which is already 3.3 inches (83.82 mm) wider than the base model C6. The increase in width of the C6.R is due to the wider axle track, which accommodates fat Michelin slick race tires and allows for a more stable weight distribution within turns.
The length of the C6.R is 2 inches (50.8 mm) longer than the Z06 road car. This is mainly made up of the combination of the large front splitter and slight overhang of the rear wing found on the race car. If the race car was to remove the aero devices the overall length of the C6.R is almost identical to the road car.
The biggest contrast between the road car and race car is found on the weighing scales. The Z06 was the lightest of the sixth generation Corvettes at 3,131 pounds (1,420 kg). However the C6.R race car is a whole 706 pounds (320.2 kg) lighter than the Z06 production car. The FIA restricts the weight of the GT1 class to a minimum dry weight of 1100 kg (2425 pounds). The C6.R came in on that figure precisely making it slightly lighter than its predecessor.
The C6.R shed weight in many areas such as the bodywork of the race car is constructed of lightweight carbon fiber, kevlar, nomex and aluminum composite. All of the glass on the race car is replaced by polycarbonate. The battery is a super lightweight Lithium/Ion battery from Braille, instead of a typical lead/acid battery. The heat shielding, sound proofing, carpets, sound system and most of the interior is removed. The dashboard is taken from the C6 production car but the entertainment system is removed, leaving the factory dash to act as more as a shell for the electronics. Finally there is only need for one seat, which is made up of a custom carbon-fibre monocoque shell and wrapped in a fire retardant upholstery.
At the time the GT1 class allowed for more freedom within aerodynamics over the GT2 class but this was still strictly monetized by the FIA. Pratt & Miller had to ensure that every aerodynamic device such as front splitter, floor, side skirts, diffuser, rear wing and gurney flap did not exceed the dimensions permitted by the FIA GT1 rule book.
At the front of the C6.R sat a completely newly designed carbon fiber front splitter. The front splitter on the previous C5-R, evolved over the five years it competed under Corvette Racing, but thanks to the cleaner front fascia of the C6, the splitter found on the C6.R was larger. It pretrouded further from the bodywork and featured two large channels on the lower side, which directed the air more accurately under the car. The entire floor of the C6.R was flat, which help direct the low pressure air to a large more complex rear diffuser than the one found on the C5-R. The new rear diffuser featured 14 venturi tunnels compared to the four found on the C5-R diffuser. The C6.R diffuser was built with leading edges at rear axle centerline, side plates and longitudinal fences. The width of the venturi tunnels were not all equal due to careful planning from Computational Fluid Dynamic design, which displayed the most advantageous way of directing the air .
Although based on the Z06, the bodywork underwent modifications but resembled the production car much closer than the bodywork of the C5-R. The front fascia remained almost identical to the Z06 production car with the large front grille being multifunctional. The middle portion of the grille was used to channel cool air to the radiator. Next to the radiator section of the grille was two ducts that directed air to the engine intakes. At the far outside edges of the grille was two brake cooling ducts, that sometimes featured body color coded covers to control brake temperatures and better streamline the front for high speed circuits. This new front fascia along with the new exposed headlights that sat flush with the bodywork allowed for much cleaner aerodynamics over the front, which reduced overall drag.
The hood featured a large waterfall extractor duct, which sealed off a majority of the radiator from the engine compartment. This design resembled the waterfall hood found on the later models of the C5-R. It allowed the heat from the front tilted radiator to extract directly to the atmosphere instead of circulating under the hood. The hot radiator air would join the cool air travelling over the car at speed and helped generate a cleaner airflow towards the rear wing, whilst adding downforce.
The fenders of the C6.R featured very aggressive louvers compared to the ones found on the C5-R. The new louver design started close to the headlights and covering the entire fender up to the windshield. The width of the louvers tapered with the shape of the hood that widened towards the windshield. These louvers helped the turbulent air space, which is created by the wheels at high speed. This system greatly reduces front end lift helping generate better stability and downforce over the front axle.
Thanks to the development of the cool suit worn by the drivers, the C6.R was able to feature side windows unlike the C5-R. The side windows featured a NACA duct located to the front of the window, which helped direct fresh air into the cabin. A small section of rear of the side window was cut out for heat extraction. Adding side windows helped create cleaner air flow over the car, which greatly reduced drag helping add to the top speed.
Finally the rear wing resembled the one found on the C5-R, but was redesigned to work better with the bodywork of the C6. The rear wing was completely made of carbon fiber and the mounts are bolted directly to the frame of the car due to the high levels of force applied to them. The wing is adjustable to suit high or low drag requirements of different race circuits. The front middle section of the rear wing featured a small rise, which was designed to catch the airflow over the roof of the C6.R.
The brakes found on the C6.R are strictly racing dedicated brakes. The rules of the GT1 class permitted the use of carbon ceramic brake rotors unlike the steel rotor rule of the GT2 class. The previous C5-R started in 1999 with Alcon Carbon brakes and switched to AP Racing in 2003. Pratt & Miller continued the use of AP Racing brakes on the C6.R.
At the time, the production Corvette Z06 was equipped with biggest most powerful brakes on a Corvette. The brakes were supplied by Brembo and featured six piston calipers with 13.9 inch (355 mm) vented rotors at the front and four piston calipers with 13.4 inch (340 mm) vented rear rotors.
The AP Racing brakes on the C6.R featured six piston monoblock calipers with 15 inch (381 mm) Hitco carbon ceramic rotors on the front and four piston monoblock calipers with 14 inch (355.6 mm) Hitco carbon ceramic rotors on the rear. Hitco supplied the carbon rotors and carbon pads with Mobil 1 supplying the DOT 4 high temperature brake fluid.
With the aerodynamic restrictions placed on the GT1 class by the FIA, mechanical grip plays a major factor for the C6.R. Fortunately the production steel hydroformed frame rails provided a lot of stiffness and Pratt & Miller capitalized on mechanical grip with the suspension setup.
Although the suspension starts with production roots, it was made up of fully adjustable race components. The construction of the suspension is supplied by Moton and starts with short/long double wishbones, fabricated steel upper & lower control arms with machined aluminum knuckles. Moton also supplies the multi-adjustable shock absorbers and damper kit with the spring coil-overs being supplied by Eibach. Finally the anti-roll bars are fully adjustable making the control of the body roll for different circuits fully customizable.
The rear suspension setup uses identical components as the front, but features some slight changes within layout, such as the rear anti-roll bar takes a unique route around the rear differential.
Both the front and rear suspension are fully independent and fully adjustable. This is integral for motorsports as each race circuit poses unique challenges, which the engineers adjust the suspension for to maximize grip. A bumpy track like Sebring will require a much softer suspension setup compared to a circuit like Le Mans.
The tire specifications, such as compound and size is mandated by the FIA, however the tire manufacturer is open for selection by the individual race teams. Corvette Racing for their first four seasons used Goodyear tires, which was partially influenced by the partnership between GM and Goodyear for the production Corvette. For the 2004 season, Corvette Racing switched out Goodyear for Michelin.
The swap to Michelin was motivated by a major performance difference found at the 2003 Le Mans 24 Hours. The Goodyears of the Corvette required changing at each pitstop whereas the Michelins on the rival Prodrive Ferrari 550 generated more grip and could be easily double stinted. After Corvette Racing transitioned to Michelin they saw an immediate difference in performance, with a six second faster lap time at Le Mans over the previous years times on Goodyears.
For the C6.R, Corvette Racing made the easy decision to stick with Michelin. The tires on the C6.R were Michelin Pilot radials, with a choice of soft, medium and hard compound for the dry and treaded tires for a wet racing. The tire size differ from the front and rear with 290/33 – R18 on the front and 310/41 – R18 on the rear.
Pratt & Miller started using BBS wheels on the C5-R, but in 2002 made the switch to OZ Racing wheels. The C6.R would make its debut in 2005 using OZ Racing wheels, but transitioned to BBS forged magnesium wheels in 2006 which remained the wheel of choice for the team to date.
The debut C6.R livery was pretty simple using just a single color. Corvette Racing had become synonymous with the use of yellow as their main color. The team started using the factory production Corvette color, Millenium Yellow, at the 2000 Petit Le Mans. For the C6.R, Corvette Racing continued with yellow but it was the new Velocity Yellow that replaced Millenium Yellow as a factory option in the Corvette range.
The main sponsor remained Compuware, but the hood logo was relocated from the high hood position of the C5-R to the front of the hood due to the new more aerodynamic shape of the C6.R.
Due to the similarity of the two C6.R Corvettes the only way to identify the difference was the #3 and #4 allocated to the cars. This led to the use of a red Corvette window banner and Velocity Yellow color coded the side mirrors used on the #3 car. The #4 car used a black Corvette window banner and had exposed carbon fiber side mirrors.
In the previous years, Corvette Racing had developed two major rivals. The Chrysler Viper GTS-R ran by Team Oreca up to 2002 and from 2003 the Prodrive Ferrari 550 Maranello. Prodrive owner David Richards was an Aston Martin enthusiast and announced in 2004 that the team had a new weapon of choice to replace the Ferrari 550 for the 2005 season. In 2004, Aston Martin replaced the DB7 with the new DB9, therefore Prodrive constructed the Aston Martin DBR9. Like the Ferrari 550, the DB9 featured a front mounted aluminum 6.0 liter, 60-degree, DOHC, four valve per cylinder, V12 making for an easy transition. The battle between Pratt & Miller and Prodrive would live on within the new cars, therefore at the first round of the 2005 ALMS season at Sebring both teams would debut their new race cars.
The first round of the ALMS 2005 season would be the gruelling 12 Hours of Sebring. If there was an event that tested race cars to their limits it was this famous endurance race. Despite being half the distance of Le Mans, many race teams would consider the 12 Hours of Sebring more demanding on a race car due to the harsh infamous bumps and mixed surface. This lead to the belief if a race car completed the 12 Hours of Sebring without a mechanical failure, it should have no issues at Le Mans.
The race started with the two Corvettes taking the lead over the two Aston Martins. Along with the Corvettes and Aston Martins the GT1 class that year had a stacked roster with entries from Maserati, Ferrari and Saleen. With eight of the 12 hours completed in the race, Corvette Racing were still running first and second in the GT1 class and ranked third and fourth overall with the two Aston Martins on the same lap. Unfortunately at the beginning of the ninth hour the #3 Corvette C6.R front brake rotor exploded at the end of the long back straight heading into the braking zone of the tight 180 degree turn 17. Johnny O’Connell was behind the wheel at the time and purposely downshifted too many gears to spin the C6.R into the tire barrier to avoid front end damage. This result was a lot of damage to the right side of the car that was repaired by the team and the #3 car re-entered the race behind the Astons. Moments later the #4 Corvette C6.R was involved in an accident with another car, which damaged the right rear suspension. Whilst trying to chase down the lead Aston Martin, Johnny O’Connell in the #3 C6.R set a new lap record. The race ended with the #57 Aston Martin taking first place in the GT1 class with the #3 C6.R finishing second and #4 C6.R taking third. It was a frustrating result for the team but the C6.R had displayed its impressive pace.
The second round of the 2005 ALMS season took place at Road Atlanta for a two hour and 45 minute race. Prodrive was running a limited season in the ALMS for the 2005 year and was not present for that round making for an easy 1-2 podium finish for Corvette Racing with a Maserati MC12 in third. Ron Fellows and Johnny O’Connell would finish ahead of Oliver Gavin and Olivier Berretta again, giving them the lead in the GT1 Drivers Championship.
For the third round of the 2005 ALMS season, Mid-Ohio would be the venue for another two hour and 45 minute race. Corvette Racing took another first and second place in the GT1 class with the Saleen S7R finishing in third. The #3 C6.R driven by Ron Fellows and Johnny O’Connell taking two in a row over the #4 C6.R of Oliver Gavin and Olivier Berretta.
The fourth race of the 2005 Corvette Racing season could be considered the most important race for the team as it was the 24 Hours of Le Mans. Aston Martin was present with their two DBR9s, giving Corvette Racing an opportunity to revenge the Sebring result. Throughout qualifying the Astons set a considerably faster lap time than the Corvettes, but when it came to the race the Corvettes were able to keep up with the pace of the Astons. The #64 C6.R was running consistently faster than the #63 C6.R due to a setup issue that caused a lack of mid turn grip. After 22 hours of back and forth fighting the #64 C6.R was leading the GT1 class over the #59 DBR9. The #58 DBR9 was running in third and the #63 C6.R was running in fourth. The two classing leading cars were swapping positions at every pitstop, but at the 23rd hour the #58 DBR9 stopped on track with a fueling issue. A few moments later the #58 DBR9 stopped in pits with a radiator issue handing Corvette Racing first and second in class and fifth and sixth overall. The 2005 Le Mans victory is considered one of the finest achievements of the Corvette Racing team as the result displayed the pace and reliability of the C6.R in its first ever season.
Returning to the USA the next round in the ALMS took place at Lime Rock. Corvette Racing finished first and second in the GT1 class and took third and fourth overall behind the two Audis. For the first time in the ALMS championship the #4 C6.R was able to take a victory over the #3 C6.R.
The fifth round of the ALMS championship was run at Sonoma, where usual duties resumed of the #3 C6.R taking first place in the GT1 class and the #4 C6.R taking second.
Round six was the two hours and 45 minute race at Portland International Raceway. Oliver Gavin and Olivier Berretta took the #4 C6.R home to another GT1 victory ahead of the #3 C6.R in second. Third place belonged to the #5 Corvette C5-R of Pacific Coast Motorsports whom had purchased chassis C5R-006 from Pratt & Miller. This would give the Corvette brand its first ever clean sweep of the GT1 class podium.
Road America was the location for round seven of the ALMS championship. For the first time in the season the #4 C6.R was able to take a back to back GT1 class victories. The #3 C6.R would take second place creating a close fight in the championship standings between the two Corvettes.
Round eight of the ALMS championship took place in Canada at Ron Fellows home track, Mosport. For the first time in the season the Corvettes victory was in jeopardy as some rule changes had been put in place to equalize the performance between the C6.Rs and the Saleen S7R of ACEMCO Motorsports. During qualifying the S7R took pole position with the #4 C6.R behind in second. Third place on the starting grid belonged to the Maserati MC12 and the #3 C6.R was starting from fourth. The Saleen was able to lead the first hour and 53 minutes of the race, but the pace made for higher fuel consumption forcing the S7R to make an extra pitstop to take on more fuel. Both Corvettes were able to make their final pit stops taking on enough fuel for the end of the race and a set of fresh tires, giving Corvette Racing another 1-2 GT1 class finish. The #4 C6.R took first place ahead of the #3 C6.R, which handed Oliver Gavin and Olivier Berretta the lead in the GT1 Drivers Championship over Ron Fellows and Johnny O’Connell.
Two rounds remained in the 2005 ALMS season. Corvette Racing was easily going to take the GT1 Manufactures Championship, however the GT1 Drivers Championship was looking to go to the wire. Round nine was the legendary Petit Le Mans at Road Atlanta. Prodrive was present with a pair of DBR9s to run the last two rounds of the season. During qualifying Johnny O’Connell would shatter the GT1/GTS lap record, which he set earlier that year. The race was very exciting with the top three positions of the GT1 class being swapped between the Corvettes, Astons, and the sole Maserati and Saleen. Unfortunately towards the end of the race the #3 C6.R suffered engine failure from a broken valve spring handing an easy victory to the #4 C6.R. Oliver Gavin and Olivier Berretta took the 2005 Petit Le Mans GT1 class victory and finished third overall giving them a 15 point lead ahead of Ron Fellows and Johnny O’Connell in the drivers standings. The #57 DBR9 finished second in class and the Maserati MC12 taking third. The #3 C6.R would be classified sixth in class, and twelfth overall.
The 2005 season finale was a four hour endurance race at Leguna Seca. The two Prodrive Aston Martin DBR9s were competing to try and give an upset to Corvette Racing. The GT1 battle was spectacular with the Corvettes, Aston Martins, Saleen and Maserati swapping positions. At the one hour mark the Corvettes sat first and second, but at the two hour mark had dropped to fourth and fifth in class as the top four cars in the GT1 class ran bumper to bumper. Ron Fellows made four passes including a fantastic pass at the Corkscrew on the #57 DBR9 at the two hour and 20 minute mark to take the GT1 lead. It looked like the #3 C6.R was setting up a GT1 victory but suffered a stuck rear wheel during a pit stop allowing the #4 C6.R to take the lead. The race finished with the #4 C6.R taking first in class and the #3 C6.R taking second. The #58 Aston took third with the #57 taking fourth.
Corvette Racing had taken the ALMS GT1 manufacturers championship and Oliver Gavin with Olivier Berretta would win the ALMS GT1 Drivers Championship with a 20 point gap over Ron Fellows and Johnny O’Connell. Corvette Racing had taken first place in the GT1 class in all but one race. The new C6.R had proven it was just as dominant as its predecessor, displaying an extremely impressive debut season.
The first Corvette C6.R built by Pratt & Miller for Corvette Racing. The C6R-001 started a new era in Corvette history in 2005 with drivers Ron Fellows and Johnny O’Connell piloting C6R-001 to GT1 class victories at Road Atlanta, Mid-Ohio and Sonoma.
The new C6.R featured a longer wheelbase over the C5-R, but a shorter overall length thanks to smaller overhangs. The new design of the C6 Corvette allowed Pratt & Miller to build a race car with more ease, due to the large front mounted grille and flush exposed headlights.
A new LS7.R engine sat under the hood built by Katech from the LS7 platform found in the Corvette C6 Z06. The LS7.R was a 7.0 liter pushrod V8 generating approximately 590 hp and 640 lb ft torque in race form due to FIA mandated air restrictors.
Although the C6.R had a rear window, the cabin and rear was separated by a wall making rear visibility impossible without side mirrors. This created the use of a small camera built into the rear fascia below the Corvette emblem that fed footage to a small screen located within the cabin where a traditional rear view mirror would be located.
The livery was all one color, the new GM color for the Corvette; Velocity Yellow. Most of the decals were colored in a contrast black, besides decals that needed to be in color such as the GT1 logo, number plates and the US flags.
C6R-001 differed from the sister car thanks to a red Corvette window banner and color coded yellow side mirrors.
After the 2005 American Le Mans Series season, C6R-001 was sold to GLPK Carsport to compete in the FIA GT championship. C6R-001 would go on to win the Spa 24 Hours in 2007 and would continue to be ran by GLPK Carsport and partners Phoenix Racing until 2010 with the introduction of the FIA GT1 World Championship.
C6R-001 was then sold to V8 Racing in the Netherlands to compete in the GT Open, where it would be restricted to compete with GT3 cars. Despite the restrictions C6R-001 managed to set the pole position for the 2014 Dubai 24 Hours race.
The sister car of C6R-001 featured an identical setup and was introduced at the same time. In its debut season C6R-002 won the GT1 class Drivers Championship for Oliver Gavin and Olivier Berretta. In the same year C6R-002 won the GT1 class in its debut at the 24 Hours of Le Mans.
Besides being allocated the #4 in the 2005 ALMS season, C6R-002 differed from C6R-001 thanks to a black Corvette window banner and exposed carbon fiber side mirrors.
After the 2005 ALMS season, Pratt & Miller sold C6R-002 to European team PSI Experience to compete in the LMES, the French GT Series including a few rounds of the FIA GT Championship upto 2008. PSI Experience sold C6R-002 to DKR Engineering that would run C6R-002 in the FFSA Championship and the FIA GT Championship. C6R-002 would compete and win races in the FFSA and FIA GT series as late as 2009 and would continue to be a front runner until the end of the FIA GT1 World Championship in 2011.
For the 2006 ALMS season Pratt & Miller built a new car for Corvette Racing. C6R-003 remained almost unchanged from the previous years chassis, however minor updates were made such as the OZ Racing Wheels were switched out for BBS forged magnesium wheels, which Corvette Racing have continued to use to date.
The livery remained almost identical to the 2005 livery and the #3 car would continue to use color coded side mirrors and a red Corvette window banner to help the team identify the two cars.
C6R-003 would go on to win round seven of the 2006 ALMS season at Road America and would be runner up in the GT1 ALMS Drivers Championship.
In 2007 chassis C6R-003 was used for round nine of the 2007 ALMS season at Mosport wearing #33 and driven by Ron Fellows and Andy Pilgrim. It was able finished third in class behind the two Corvette Racing C6.Rs allowing the Corvette brand to complete another GT1 class podium sweep. The #33 car featured a unique livery in the Ron Fellows ALMS Victory Edition paint scheme. This paint scheme was made up of Artic White with Monterey Red Metallic flashes on the front fenders, which became a limited edition paint scheme for the production 2007 Corvette C6 Z06.
After the race at Mosport chassis C6R-003 was sold to Luc Alphand Aventures at the end of 2007.
Luc Alphand Aventures entered C6R-003 into the 2008 Le Mans Series taking two class victories and a podium finish in all five rounds. The team would also enter C6R-003 into the 2008 Le Mans 24 Hours, where it would finish fifth in the GT1 class. Luc Alphand Aventures continued racing C6R-003 in 2009 in the FFSA GT Championship and a few rounds FIA GT where it accomplished a combined seven podiums.
Unfortunately C6R-003 was destroyed when the Luc Alphand Aventures transporter caught fire on route to Albi, France on the 2nd of September 2009.
The sister car to C6R-003 featuring an identical setup but identified by a black Corvette window banner and exposed carbon fiber side mirrors.
C6R-004 won the GT1 class at its debut race at the 2006 Mobil 1 Twelve Hours of Sebring. It would take five GT1 class victories in the hands of Corvette Racing in 2006 including the 24 Hours of Le Mans. C6R-004 helped Corvette Racing secure its sixth straight ALMS GT1 Manufactures Championship and gave Oliver Gavin and Olivier Berretta their second straight ALMS GT1 Drivers Championship.
At the end of 2006 C6R-004 was sold to Luc Alphand Aventures where the team entered the car into the 2007 LMES championship where it won its debut race with the team at Monza. For the 2007 season C6R-004 also competed at the 24 Hours of Le Mans finishing seventh in the GT1 class and was entered into the Spa 24 Hours under the FIA GT Championship where it finished sixth in class.
C6R-004 raced with Luc Alphand Aventures between LMES, FFSA and FIA GT races until the end of 2009.
C6R-005 made its debut at the 2007 Mobil 1 Twelve Hours of Sebring. Ron Fellows had retired from a full time driving duties for Corvette Racing and became a third driver for the endurance races such as Sebring, Le Mans and Petit Le Mans. To cele
brate the impact that Ron Fellows had made on Corvette Racing over the last eight years General Motors decided to produce a series of just 399 limited edition Corvette (C6) Z06 in th
e Ron Fellows ALMS GT1 Champion paint scheme. This was the first Arctic White Z06 available and featured Monterey Red Metallic flashes on the front fenders with Fellows accomplishments in the ALMS with Corvette Racing integrated into them. Fellows personally signed and numbered the the inside of the glove box lid on each road car with Fellows personally buying #001. C6R-005 practiced and qualified at Sebring in the traditional Velocity Yellow, but ran the race in the Ron Fellows ALMS GT1 Champion paint scheme.
For the 2007 season Corvette Racing had switched from using Sunoco racing fuel to E10 Ethanol, made of 10% ethanol and 90% gasoline. C6R-005 was tested at round 2 of the 2007 ALMS Championship with new parts such as a new carbon fiber driveshaft and a new small air conditioner. The A/C unit drew air in from ducts integrated into the side mirrors and was incredibly light, compact and allowed the engine to focus on its main duty of powering the C6.R down the Mulsanne straight. This eliminated the use of the cool box, which was filled with ice water and was connected to the cool suit the drivers wore featuring a network of piping allowing the cool water to flow through it. At each pitstop the cool box needed to be replenished, which also included the need to unplug and plug the cool box back into the drivers suit. This increased weight to the car and also added time and risk to pitstops. The A/C unit eliminated this problem.
The rear of C6R-005 and C6R-006 changed aesthetically due to the fan located in the rear of the C6.R that helped cool the the heat exchangers for the engine oil, differential and transmission. This resulted in the rear vent that was designed to resemble a license plate was increased in size. Towards the end of 2007 ALMS season Pratt & Miller added an additional slim vent directly below the license plate styled vent allowing for an increase in air flow.
Besides the Ron Fellows ALMS GT1 Champion paint scheme, C6R-005 livery remained mostly unchanged from the previous two years. However at the ALMS season finale at Leguna Seca where the C6.Rs wore the ‘Jake’ paint scheme designed by badboyvettes.com. C6R-005 as the #3 car had a large black stencil style jake skull over the Velocity Yellow base, where as the C6R-006 as the #4 car had a reversed version of the same paint scheme.
C6R-005 under the hands of Corvette Racing accomplished three GT1 class victories and 11 podiums throughout the 2007 ALMS season. At the end of 2007 C6R-005 was sold to Carsport Holland to compete in the 2008 FIA GT Championship as Phoenix Carsport were it collected one victory and six podiums. For the 2009 FIA GT season the team ran under the name of PK Carsport where it accomplished five podiums, two wins including the overall win at the 2009 Spa 24 Hours. C6R-005 finished its racing career under Phoenix Carsport in the 2010 FIA GT1 World Championship.
The sister car to chassis C6R-005 and featured an identical setup also made its debut at the 2007 Mobil 1 Twelve Hours of Sebring where it finished first in class. As part of Corvette Racing C6R-006 throughout the 2007 ALMS season accomplished a podium at all 12 rounds of the season including nine GT1 class victories. This handed Corvette Racing their seventh consecutive ALMS Manufactures Championship and secured the third straight GT1 Drivers Championship for Oliver Gavin and Olivier Berretta.
Seeming a major part of a victory at Le Mans is based upon how much time the car spends in pit lane, Pratt & Miller decided to design a cylinder deactivation system for slow periods of the race such as safety cars, which helped save fuel. Unfortunately after only one hour and 39 minutes into the 2007 Le Mans 24 Hours C6R-006 as #64 stopped on track and was forced to retire. This would be the first time Corvette Racing had a car fail to finish at Le Mans. The disappointment amongst the team and drivers was major seeming the #64 car was attempting to defend its GT1 Le Mans champion title. The retirement was later traced to the carbon fiber propshaft had delaminated due to the harmonics of the engine in cylinder deactivation mode. Corvette Racing would not use this system again, however General Motors decided to incorporate the technology into the 2014 Corvette C7.
The Corvette Racing livery for C6R-006 remained almost identical to the livery used the previous two years but used the ‘Jake’ design for the ALMS season finale at Leguna Seca. The ‘Jake’ paint scheme differed from the #3 car as it was reversed therefore featured a large yellow stencil styled Jake Skull over a black body base color.
At the end of the 2007 ALMS season, Pratt & Miller sold C6R-006 to the Belgium based race team Selleslagh Racing Team (SRT). With SRT C6R-006 competed in the 2008 FFSA championship and a few FIA GT rounds where it would accomplish a combined nine podiums and three victories. SRT would run C6R-006 in 2009 between the FFSA championship and the FIA GT championship picking up a combined eight podiums and three victories. C6R-006 finished its racing career in 2011 in the FIA GT1 World Championship running as ‘Mad Croc’ in 2010 and China Exim Bank in 2011 where it won the final two races of the season and championship.
C6R-007 was on of the final C6.R chassis built for the GT1 class. It remained unchanged to the previous two chassis made for the 2007 season but Corvette Racing decided to switch to E85 fuel for the 2008 ALMS season. The E85 was made up of a mix of 85% ethanol and 15% gasoline. The ethanol was produced from sustainable and carbon neutral sources but created issues for the team. During testing in late February, a post-test inspection revealed that the E85R fuel was damaging the adhesive used to construct the twin fuel cells of the C6.R. Whilst a new fuel-cell bladder design was being constructed for the E85, Corvette Racing used the E10 blend of fuel used in the 2007 season for the opening round of the 2008 ALMS season at the Mobil 1 Twelve Hours of Sebring.
For the first time on the C6.R the main livery (excluding special edition paint schemes) had changed. The main base color remained Velocity Yellow but now featured a lot of black accents. These accents included black headlight casings, black rocker panels, black wheels and a black rear fascia. A new black stripe travelled the whole length of the car called the ‘Jake Scrape’. It received this name as it was made up of a thick black line on the right side and four slim separated lines on the left, that resembled the bottom section of the Jake Skull as if it had been dipped in black paint and scraped across the car. On the black rear fascia the Jake Scrape switched to a contrast Velocity Yellow. The main sponsor, Compuware, had a new logo featuring three shields behind the first half of the Compuware name. These shields were colored blue over green with the final shield being yellow. The letter ‘O’ in Compuware featured a small orange shield. For C6R-007 using #3 separated differed from the #4 C6.R by using a red Corvette window banner, color coded Velocity Yellow side mirrors and rear wing end plates.
For the 2008 ALMS season chassis C6R-007 finished no lower than 2nd place in class, collecting nine GT1 class wins and 12 podiums. This awarded Corvette Racing their eighth straight ALMS Manufactures Championship and gave Johnny O’Connell and Jan Magnussen the GT1 Drivers Championship breaking the three year streak of the #4 car.
For the 2009, Corvette Racing used chassis C6R-007 for three races, which included round one and three in the GT1 class of the ALMS season and the 2009 Le Mans 24 Hours. This was due to the lack of competition in the GT1 class. Prodrive decided to build in conjunction with Lola an Aston Martin LMP1 car, and the rest of the competition including Saleen, Ferrari and Maserati withdrew from GT1. This resulted in the decision for Corvette Racing to build a GT2 car for the 2009 season, however the team wanted lead the score with Prodrive in the GT1 class at Le Mans. Corvette Racing decided to use the GT1 cars for one last run at GT1 class Le Mans victory. The score between Corvette Racing and Prodrive was 2-2 with Corvette Racing winning the GT1 class at Le Mans in 2005 and 2006, and Prodrive Aston Martin taking 2007 and 2008. The final race for C6R-007 was the 2009 Le Mans 24 Hours. Due to the retirement of the #64 Corvette, C6R-007 took the GT1 class victory with Johnny O’Connell crossing the finish line doing a running burnout, sending off the GT1 Corvette in style.
For 2009 C6R-007 was painted in the new GT1 Edition limited paint scheme for the production Corvette (C6) Z06 to celebrate the success Corvette Racing had in GT1. The livery was made of a Velocity Yellow base, black headlight bezels, black wheels and a black rear fascia. The top of car featured a black design with a subtle jake skull on the hood, which was separated from the yellow with a silver accent.
C6R-007 was later sold to a private collector.
The sister car to C6R-007 featuring an identical setup, was the final GT1 Corvette built by Pratt & Miller. C6R-008 made its debut at the 2008 Mobil 1 Twelve Hours of Sebring, where it collected a second place finish in class behind the sister C6.R. During the 2008 ALMS season C6R-008 accomplished eleven GT1 class podiums and three GT1 class victories.
For the 2008 season the livery was identical in to the sister C6.R, but continued the tradition of the #4 crew by using a black Corvette window banner, and exposed carbon fiber side mirrors and rear wing end plates.
Chassis C6R-008 was used for three races in the 2009 season like the sister car. After finishing second in class to the C6R-007 at the 2009 Mobil 1 Twelve Hours of Sebring, C6R-008 took the GT1 class victory at the second race for team during at the third round of the 2009 ALMS season at Long Beach.
Unfortunately at the final race for C6R-008 at the 2009 Le Mans 24 Hours, the GT1 class victory was stolen away due to transmission failure with less than three hours remaining in the race. The ACO rules mandate that a car must retire unless it can make its way to pit lane without assistance. C6R-008 came to a stop only 100 yards short of pitlane, forcing a retirement. This spoiled the perfect end to the GT1 Corvette chapter as the #73 Luc Alphand Aventures C6.R was running in third behind the #63 Corvette Racing C6.R in second. This would have been the first Corvette GT1 class podium sweep.
For the 2009 season C6R-008 was painted in the second option of the new GT1 Edition limited paint scheme for the production Corvette (C6) Z06. This livery was a contrast to the Velocity Yellow option, with the C6.R being all black besides a Velocity Yellow design over the top of the car, featuring a slightly darker yellow Jake Skull on the hood. This Velocity Yellow design was separated by a silver outline just like the one found on the #3 car.
|Model:||Chevrolet Corvette C6.R|
|Body Style:||Two-door coupe hatchback|
|Layout:||Front engine, longitudinal powertrain placement|
|Driveline:||Rear wheel drive|
|Data Logging System:||Pi Research Sigma Elite|
|Battery:||Braille 38 Ah super light weight lithium-ion 12 volts|
|Steering:||Power-assisted rack and pinion|
|Steering Column:||Production Corvette with tilt|
|Instrumentation Display:||Pratt & Miller built Pi Research Systems 6" LCD display|
|Rear View Display:||Intel|
|Data Acquisition:||Cosworth Electronics telemetry data systems measuring steering angle, gearbox position, cruising speed, RPM, throttle, brake, time elapsed and four spare data channels|
|Headlights:||Hella 15 Volt|
|Safety Equipment:||Willans six-point harness, rear view mirror, drivers side crash box, window net, roll cage|
|Fuel Cell Capacity (US Gallons / Liters):||26.4 / 100|
|Manufacturing Location:||Pratt & Miller, New Hudson, Michigan, USA|
|Engine:||Katech LS7.R, 7.0L V-8|
|Displacement (cu in / cc):||427 / 6997|
|Engine V-angle:||90° cylinder angle|
|Valvetrain:||16-valve, pushrod with overhead titanium valves, two valves per cylinder|
|Air Intake Restrictor Size (mm / In):||Two (30.6 mm / 1.2)|
|Bore (mm / In):||106.2 / 4.18|
|Stroke (mm / In):||98.42 / 3.875|
|Deck Height (mm / In):||235 / 9.25|
|Cylinder Bore Type:||Plate-honed|
|Cylinder Bore Spacing (mm / In):||111.7 / 4.4|
|Cylinder Case Material:||Aluminum|
|Cylinder Head Material:||Aluminum with CNC ported|
|Crankshaft:||Forged billet steel|
|Main Cap Material:||Nodular Iron|
|Throttle Systems:||Individual runners with carbon fiber proprietary butterflies|
|Pistons:||Mahle cast-aluminum flat-top pistons|
|Exhaust Valves:||Vertical sodium filled (41 mm / 1.6 in)|
|Exhaust Valve Axis Angle:||12°|
|Exhaust System:||Pratt & Miller hydroformed fabricated exhaust manifold headers with unique "quad flow" collector flanges, side exit|
|Engine Management:||Bosch Motronic MS 4.0|
|Fuel:||Sunoco Racing Fuel (2005-06), E10 (2007), E85 (2008-09) provided by Ethanol Promotions and Information Council|
|Fuel Delivery:||Kinser sequential multi-point electronic indirect fuel injection|
|Lubrication:||Mobil 1, Dry sump|
|Horsepower (hp / kW @rpm):||590 / 440 @ 5400 rpm|
|Torque (lb ft / Nm @ rpm):||640 / 868 @ 4600 rpm|
|Transmission:||Xtrac 6-speed sequential|
|Clutch:||AP Racing Multi-plate carbon fiber|
|Differential:||AP Racing adjustable mechanical limited-slip differential|
|Drive Shaft:||Carbon-fiber constant-velocity tripod slip-joint shafts|
|Spark Plugs:||Katech Performance|
|Water Radiator:||C&R Racing Corvette-spec MARSTON core water cooling system.|
|Oil Radiator:||C&R Racing Corvette-spec MARSTON core oil cooling system.|
|Front:||Moton independent, short/long double (SLA) 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 (SLA) 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):||Hitco carbon ceramic (14.9 x 1.4 / 380 x 35)|
|Rear Rotors (in / mm):||Hitco carbon ceramic (13.97 x 1.25 / 355 x 32)|
|Front Calipers:||AP Racing six-piston monoblock|
|Rear Calipers:||AP Racing four-piston monoblock|
|Brake Fluid:||Mobil 1 DOT 4|
|Tire:||Michelin Pilot Radial||Michelin Pilot Radial|
|Tire Compound:||Soft, Medium, Hard and Grooved Wet||Soft, Medium, Hard and Grooved Wet|
|Wheels:||OZ Racing Wheels, single center locking wheel nut||BBS forged magnesium, single center locking wheel nut|
|Front wheel size (Inches):||12.5 x 18||12.5 x 18|
|Rear wheel size (Inches):||13 x 18||13 x 18|
|Front tire size:||290 / 33 – R18||290 / 33 – R18|
|Rear wheel size:||310 / 41 – R18||310 / 41 – R18|
|Wheelbase (in / mm):||105.7 / 2684.78|
|Overall length (in / mm):||177.6 / 4511|
|Overall width (in / mm):||78.7 / 1999|
|Overall height (in / mm)||45.8 / 1163|
|Dry weight (pounds / kg):||2425 / 1100|
|Front axle track (in / mm):||62.2 / 1580|
|Rear axle track (in / mm):||63.1 / 1603|