Statements from General Motors have all but confirmed that a twin-cam, flat-plane crank V8 closely related to the Chevrolet Corvette C8.R’s racing engine will eventually appear in a street-legal Corvette.
GM recently announced that the C8.R will be powered by a naturally aspirated, 5.5-liter V8 with dual overhead camshafts (DOHC) and a flat-plane crankshaft—twin departures from the Corvette’s traditionally cam-in-block and cross-plane crank configuration. Stefan Cross, GM’s assistant manager for product and brand communications, confirmed to The Drive that a derivative of this engine will eventually be found in a road car.
“FIA [LM GTE] rules state that 300 copies of the engine must be produced for a production car, so the C8.R does have a future production-based engine,” Cross told The Drive in an email, though he couldn’t discuss details of the car this engine will eventually propel.
The C8.R’s 5.5-liter displacement is the largest allowed for a naturally aspirated engine under FIA LM GTE regulations, so we can’t be sure the road derivative will share a displacement with the race car. We do know, however, that the engine will use the C8.R’s DOHC cylinder head design, as LM GTE regulations stipulate that “cylinder head castings must come from the series production engine.”
Whether the road and race engines will share the flat-plane crank responsible for the C8.R’s exotic, Ferrari-like exhaust note may seem uncertain, but we believe LM GTE’s technical outlines tell us enough to conclude the street engine will share this crankshaft configuration.
Chevrolet Corvette C8.R
FIA documents state that a homologated LM GTE car’s crankshaft must be no more than 10 percent lighter than that of the production engine on which it is based. Because our friends at Pink Sock Racing (with whom we’ve previously discussed microwave pulse ignition) tell us that the difference in weight between cross-plane and flat-plane cranks can be as much as 30 to 50 percent, we’re all but certain this means that the road-roaming version of this engine can’t have a cross-plane crank.
Chevrolet Corvette C8.R
As for the engine’s aspiration, years worth of gossip have muddied the waters beyond hope of clarity. One rumor claimed that a naturally aspirated, 5.5-liter unit will generate a Z06-worthy 600 horsepower and 620 pound-feet of torque somewhere down the line, and that a twin-turbo, presumably ZR1-spec version will lay down as much as 820 horsepower. There’ll be no knowing for sure until GM comes clean about its faster and fastest C8s, which, by our measure, are probably still years from release.
Chevrolet Corvette C8.R Concept
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