2025 Corvette C8 ZR1 LT7 Engine
Previously, no Corvette shipped from the factory has been turbocharged. They have featured forced induction by way of supercharging which was first available in the C6 Z06 and later in the C7 Z06 and ZR1. But supercharging did not work in the C8 ZR1, partly because they are inherently heavy in the wrong area: on top of the engine. The problem with turbochargers in the C7 is that, it being a front engine car and the fact that the optimum location for turbochargers was the side of the engine meant that it limited the ability to turn the wheels.
They also extract an efficiency penalty; according to LT7 designer Dustin Gardner obtaining 1,000+ horsepower from a supercharged engine would require a 200 horsepower penalty just to turn the supercharger. Turbochargers, since they are powered by the exhaust, have no such requirement. According to GM President Mark Reuss, the turbos provide 20 to as much as 24 psi of boost.
The LT6 found in the C8 Z06 Corvette was developed in parallel with the LT7 and so they both feature a 5.5 liter DOHC blocks with flat plane crankshafts. The LT7 has some upgrades including beefier piston rods. The different rods changed the compression ratio to 9.8:1 due to the boost requirements. The LT7 cylinder heads were revised to accomodate the lower compression ratio and there is a new intake system tuned for twin turbochargers. There is also a secondary port fuel injection system added to deliver the needed additional fuel to support the engine’s output.
A good idea that continues: The engine builder signature badge - the same as found on the LT6 installed in the Z06 - is part of the ZR1.
One option, last available in the 2017 Corvette was RPO PBC, the Engine Build Experience. It enabled the new Corvette purchaser to, under the guidance of a GM employee, build their own engine. At $5,000 a pop it was not a popular option and only 32 were purchased in 2017, the last year it was available.
GM quotes the weight of the ZR1 coupe at 3,670 lbs. (1,665 kg) and 3,758 lbs. (1705 kg.) for the convertible. This compares to 3,366 lbs (1,530 kg) for the Z06 coupe. As of September, no 0 - 60 or 1/4 mile times, track lap times or top speed have been announced other than the 1/4 mile time is estimated to be under 10 seconds and the top speed will be over 215 mph.
What would a C8 be without an easter egg? GM did not disappoint and similar to what was done on the LT6 engine in the Z06, a Gemini rocket can be found here and there on the LT7. Gemini was also the name of the two astronaut space capsule that preceded the Apollo three astronaut capsule.
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