The supercharged 6.2L V8 LT5 engine fitted to the 2019 Chevrolet Corvette ZR1 may go down in history as one of the greatest engines GM ever produced, especially if the company’s EV-heavy future reaches its logical conclusion. And now, we’ve uncovered a few interesting details about the LT5 that we’d like to share with you here today.
Some basics first. The V8 LT5 was rated at 755 horsepower and 715 pound-feet of torque in standard form, with power increasing to 772 horsepower when fitted with the C7 Corvette ZR1’s optional Performance Intake. Even the lower figure is extremely impressive, since it represents a specific output of almost exactly two horsepower for each of the engine’s cubic inches.
This, says SAE International, is “remarkable for a single-cam pushrod V8 with lineage reaching back to 1955”. That description very nearly applies to Top Fuel dragster engines too, and they produce over 11,000 horsepower from 500 cubic inches, or 22 horsepower per cubic inch, but that’s with the help of expensive nitromethane fuel, potential noise problems and a complete rebuild every few minutes. For a production road car engine, two horsepower per cubic inch is outstanding.
The LT5 engine was a development of the supercharged 6.2L V8 LT4 fitted to the Corvette C7 Z06, the third-generation Cadillac CTS-V and the 2017 Camaro ZL1. Among many other changes, the LT5 gained a different Eaton-developed Twin Vortices Series supercharger which spun more slowly (2.4 times crankshaft speed compared with 3.1 times for the LT4) but had a 52 percent greater displacement. Peak boost therefore increased from 9.4 to 14 pounds per square inch.
The larger supercharger required just one of the engine’s horsepower to turn it when cruising, but this rose to 110 horsepower when it was operating at maximum boost and airflow. The parasitic loss from the LT4’s supercharger was less severe at 94 horsepower. However, the LT5 compressor essentially absorbed only an extra 16 horsepower in return for adding over 100 horsepower to the total output.
The LT5 engine’s impressive performance was also aided by two large intercoolers which provided double the LT4’s charge-air heat rejection. All other things being equal, an engine can only benefit from being fed cooler air, so this was an important factor.
More power also means more chance of things going wrong. Corvette engineers got round this in several ways, including the following:
- Fitting a larger key slot at the front end of the crankshaft to handle the supercharger’s drive load
- Using a new alloy steel for the crank for higher tensile and yield strength
- Upgrading the main bearing inserts to a tri-metal material
- Strengthening the eight-speed automatic transmission’s flex plate and the seven-speed manual’s flywheel
- Increasing the number of ribs in the drive belt from eight to 11
In addition, two muffler valves (one passive, one electronically controlled) open when the Corvette C7 ZR1 is being driven aggressively, an 800 degree stream of exhaust trails out of the car, providing visible flames in low-light conditions.
Finally, the LT5 engine enabled the Corvette C7 ZR1’s quoted top speed of 212 mph, which was achieved in seventh gear in a Coupe with the eight-speed automatic gearbox and the standard low-mount rear wing. The C7 ZR1 Convertible was slightly slower at 208 mph, while fitting the optional high-mounted wing and front splitter package would reduce the terminal speed by 10 mph due to extra aerodynamic drag, though the additional downforce would improve the car’s cornering ability.
A car’s top speed is more difficult to define than most people imagine, since it depends on several variable factors. Chevrolet therefore fitted a limiter to prevent the C7 ZR1 from exceeding 215 mph, if conditions made that possible, in order to protect the Michelin tires.
Want to stay up to date on fast GM cars and trucks? Then subscribe to GM Authority for more Corvette news, Chevrolet news and obsessive GM news coverage.
Comments
Speed governed to 212 mph, if that doesn’t just wad your panties! 😆
Yea, because the opportunity to exceed 212mph presents itself every other day. 😉
“which was achieved in seventh gear in a Coupe with the eight-speed manual gearbox”, did I miss something?
I had to read that twice and I was still confused. I think it’s 8 speed auto and 7 speed manual is what he meant.
It wasn’t the manual car. The automatic one was the one at the track hitting 212
You’re right, of course. The article has been corrected.
And the “Autobahn” weaps.
Put it in the C8 ZO6 I have been waiting for.
It is common for a vehicle to achieve top speed in less than top gear. Harley Davidson Police drop a gear to get to top speed.
When using the last gear the final drive ratio in most gear boxes is an overdrive gear for fuel economy only and cannot be used for top speed due to the extreme forces caused by drag. Thus the second to last gear must be used to make top speed runs.
Actually it was the automatic car that hit 212 and it had the special order 2.41 axle rather than 2.73
I suspect recalls are already pending won’t be long before things start breaking. It is after all a GM product…..
And what superb “product” you’re here to push on a GM site?.
Dodge lmao. Guaranteed.
“Performance Exhaust” as stated in the article doesn’t exist from GM. However a “Performance Air Intake” is offered.
“17HP and 26% restriction reduction @ 630g/s”
755+ 17= 772
so…Ram Air package…RIP Firebird
Crud, that’s my mistake. Thanks for the catch, Juan!
I wish that since these engines have literally nothing to do with the originals (LT5, LS7), GM would think up new names to go with them so not to get confused with the TRULY GREAT ORIGINAL ENGINES THAT CARRIED THESE NAMES!! Come on GM the LT5 was a Truly Great Aircraft inspired, 32 valve four cam Lotus Designed piece, and the LS7 WAS A BRUTE BIG BLOCK RAT ENGINE !
These new computer designed, controlled, modern, (yes remarkable!) engines have ZERO in common with what you have named them!
The LS7 was not a big block by definition.
I think BB was talking about the 1970 LS7 454 in.³ displacement. 465 hp gross. It was to be an option for the Corvette. But none were ever sold with this engine. It was only sold as a crate engine.
Chevy introduced the 427 in 1966 for all full size Chevys and Corvettes. Yes it was a big block. The C6 Z06 had a small block punched out to 427 ci. and it was designated as such on the emblems
However I agree that they should come up with new numbers for new concepts. There are plenty to choose from. 🙂
I had an LS7 454 put in my 71 Chevelle when the engine blew. I went from 235 hp to 465 hp and I was doubly impressed with my car. I sold it just before going in the Army and regretted it every day after. That platform was outstanding when linked with the right rear end and transmission. It wasn’t a 427 but it was the next thing to it.
Years ago, 2000-2001, a small amount of engine builders and ex GM ECU engineers took the LS1 and bored and resleeved the 5.7 block to 4.0 piston diameter and reconfigured the heads/valves, and cam, to produce 500 plus N/A HP. They deemed it the 427 7.0 liter years before today’s new LS7 505 HP. Rumor, GM took that lead and created the new LS7… same for the 5.7 LS6 405 HP changing heads and cam. The LS block is different from the small block of the 60s and 70s just like the new LT is different from the original LT engine in many ways. Instead of new charges, replacements are coming…
So will EV replace the petroleum engine in 5 years like cell phones replaced the pay phones then replaced the home phone?
Charging stations could be the next aftermarket boom with fast charging and mobile charging on the EV car/trucks/SUVs itself to eliminate stationary chargers? Who knows…
But in the meantime, build those LS and LTs! These motors are rock solid and take huge amounts of abuse and keep on going.
Supercharged = Not Eligible
Many have put long tube headers with different mufflers with the performance air intake. LT headers added another 25-27 hp. They really talk about feeling the seat of the pants power in top of 2nd and all of 3rd. I hear there is a different pulley that adds another 50 hp. Adding meth increases another 15 hp. All external add ons for around 2,500 and for around 90 hp gain.
An amazing engine! However I wish people would stop saying that engine has a lineage dating to 1955. The LS platform only shares its bore centers with the earlier SBC variants and nothing else.
Interesting that GM hasn’t optioned versions of this engine into the C8.
I think it’s funny they governed it at 215 yet they could only achieve 212. I understand that conditions vary and are critically important in top speed but I have to assume that GM probably did those runs in as close to ideal conditions as they could. . I mean unless you’re going straight downhill trying to reach a higher speed then 212. At that point then they would have to save the tires cause 215 is the tires limit. News flash, if you achieve 215 mph in a stock-ish car the manufacturer only reached 212 your tires are probably not a concern of yours. It shouldn’t be anyway. If your will is up to date should be.
The top speed was achieved at the Automotive Testing Papenburg high speed oval in Germany.
Ovals are not considered ideal for maximum speeds unless that maximum speed isn’t much.
None the less, self correction here, “Speed governed to 2̶1̶2̶ (215) mph”, there goes my panties! 😆
The car may have been tested under ideal conditions but all you need is a 5mph tail wind and you’ve exceeded the 215. They can’t control the weather you will be driving in.
It’s called the wind tunnel
Smoke them rears at the next Cars and Coffee, boys!
Quite something that LT5 but just a thought about GM engines our 2009 G8 GT has 153,000 miles on it and not tick from the valve train not a hick up from the trans. under any conditions not one issue from the cyl. deactivation no mods what so ever and can do 150 plus just say go. Best mid performance car and engine on the planet?
Thanks Holden you Aussie made one fine automobile !!!!!!
Wish GM would hold onto the best instead always looking for the best.
Guy’s: 2 item’s they “(didn’t)” mention!? // I think the reason they went thru the tire’s: Their chosen [shocks] were not suited for that application! Also: the ECU controlling the coil-packs: If the coil’s were a Autobahn designed internals; the output would be/get greater output: I think?!? [just a theory]
I’m very surprised and disappointed GM never officially put C7 ZR1 around the Nurburgring like they did C6 ZR1 where it did a great job running a 7:19:63. Surely this 755hp C7 could have run close to 7:00 flat??
The best Corvette since the 63-67………!!!!!!!!!!!!!!!!!!!!!!!!!
“The larger supercharger required just one of the engine’s horsepower to turn it when cruising, but this rose to 110 horsepower when it was operating at maximum boost and airflow. The parasitic loss from the LT4’s supercharger was less severe at 94 horsepower. However, the LT5 compressor essentially absorbed only an extra 16 horsepower in return for adding over 100 horsepower to the total output”
Does this paragraph leave anyone else scratching their head ? Is the supercharger taking 110hp or 16hp to turn it at max boost?
Coffee finally kicked in. Please disregard previous post.