The transformation from road to race car is extensive
Road cars and their endurance racing counterparts may look alike, sometimes sharing body panels, headlights, and even engine architecture, but in general, the stripped out, lightened race cars you see competing at Le Mans and elsewhere are nothing like the vehicles you can go out and buy. Chevy says its Corvette C8.R, however, shares more parts with its production equivalent than any other Corvette race car to date. Though that may be true, the list of changes from road car to race car is still extensive. Let’s go over some of the biggest differences between the regular Corvette and the C8.R that will race in the IMSA WeatherTech SportsCar Championship.
Let’s start with the engine. Motivating the road-legal Corvette is the now familiar 6.2-liter pushrod V-8 codenamed LT2—updated from LT1 in the C7—for 2020. The powerplant makes 495 hp and 470 lb-ft of torque when equipped with the optional performance exhaust. The C8.R on the other hand makes 500 horsepower (no word on torque) from its 5.5-liter DOHC V-8. These two engines are basically polar opposites. The V-8 in the race car has overhead cams and a shaft, which together allow it to rev higher and breathe better. One result of this is its much higher specific output. The LT2 retains the same basic overhead-valve design that GM small blocks have used for decades, and its cross-plane crank means it won’t rev as high as the race car. Though peak torque arrives at a relatively high 5,150 RPM, the LT2 will make most of its torque down low in the rev range. The engine in the race car is more than likely tuned for high-end power to help deliver maximum punch down the long straights of a track.
Both engines feature dry sump lubrication, direct injection, and are unaugmented by turbos, superchargers, or electric motors of any kind. The transmissions, however, are very different. The LT2 in the regular ‘Vette is mated to an eight-speed dual-clutch unit by Tremec, but the C8.R features an Xtrac six-speed sequential racing gearbox. Dual-clutch transmissions are quick, but the six-speed sequential in the race car is likely even faster.
Like the C7 and the C7.R, the two versions of the C8 Corvette share a wheelbase—107.2 inches. Unlike the last-gen car, the C8 and C8.R also share an overall length of 182.3 inches. They are different in every other dimension, however, especially weight. When MotorTrend weighed the C8 Stingray with the Z51 performance package it came in at 3,587 pounds (1,627 kg), a gain of 151 pounds (68 kg) over the C7 Stingray. The C8.R is a featherweight by comparison. Chevy quotes a weight of just 2,733 pounds (1,240 kg) for their mid-engine racer. The race car is also 4.6 inches wider and 3.4 inches lower than the standard Corvette.
Aerodynamics is one of the biggest differences between the road-going C8 and C8.R. The road car has to comply with road safety standards and, as a result, can’t sport a massive rear wing and huge dive planes. And while racing regulations do exist to try and control what the cars are capable of, race engineers get a lot more freedom to play with the air and help produce downforce and reduce drag on the C8.R.
You’ve probably heard the old cliché that a Formula 1 car can drive upside-down on the roof of a tunnel if it’s going fast enough. That’s actually possible as long as it develops more than its own weight in downforce. Though the team at Chevy won’t quote an exact number, they say the C8.R makes 10 percent more downforce than the C7.R it replaces. The road-going C8 makes 400 pounds (181 kg) of downforce at 180 mph (290 km/h) with the Z51 pack equipped. Expect the race car to make much, much more than that.
Stopping and Sticking
Brakes and tires are hugely different between the two cars. The road-legal C8 has normal steel brakes comprised of 13.3-inch rotors up front and 13.8-inch rotors in the rear. All four corners are clamped down by four-piston calipers. The race car gets six-piston monoblock calipers up front to help save some weight, and a four-piston setup in the rear. It still uses steel rotors, but the discs are much bigger, measuring 15.35 inches up front and 14.0 inches out back. Not only that, but the street-legal ‘Vette is brake-by-wire, whereas the C8.R is a conventional, manual setup.
Suspension setups differ, too. The regular ‘Vette uses a conventional passive spring and damper setup, that can be upgraded to Chevy’s magnetorheological dampers. The suspension in the race car uses a short/long arm (SLA) double-A-arm setup, fabricated steel upper and lower control arms, and fully adjustable coil-over shock absorbers.
When it comes to rubber, the C8 Stingray uses Michelin Pilot Sport 4S three-season tires, but the racer sits on Michelin-supplied slicks. The wheels of the race car are 4 inches wider at the front and 2 inches wider at the rear when compared to the standard car. Diameter on the C8.R is 18 inches all the way around while the street car sits on a staggered, 19-inch front, 20-inch rear setup.
The C8.R will make its racing debut at the Rolex 24 at Daytona on January 25, 2020.