The upcoming C8 Corvette Z06 will have a flat-plane-crank twin-turbo dual-overhead-cam V8, at least that’s the word from Motor Trend today.
The magazine says “a deep source on the Corvette team” has confirmed the new Z06 will borrow the twin-turbo engine from the upcoming C8.R race car.
“Everyone thinks it will be a small block, but it won’t be,” the source reportedly told Motor Trend. “Listen to the race car.”
Indeed, in a comparison of the sounds from the current C7.R car, which has a known cross-plane-crank V8, and a camouflaged C8.R testing at Sebring, Motor Trend believes there is a significant difference.
Writes the magazine: “The C8.R exhibits an entirely different exhaust note, one consistent with a flat-plane-crank engine design. Key characteristics to listen for: a higher-pitched exhaust note, a consistent exhaust note without the pushrod’s staccato bass line, higher RPM than a pushrod motor typically reaches characterized by longer times between upshifts, and lightning quick downshifts wherein the engine spins up to higher RPM much faster than a pushrod engine.”
MT points out that flat-plane-crank engines have key advantages for racing, including smaller, lighter crankshafts that spin up faster than cross-plane-crank V8s and lose less power to rotational inertia, plus improved performance and combustion efficiency because of better exhaust scavenging (which pulls the last exhaust gases out of a cylinder faster with reflected pressure waves).
The drawback to FPC engines, however, is balance problems as FPC V8s have only half of their vibrations cancelled out naturally, causing vibrations that only worsen as the speed climbs. “Aside from being annoying in the cockpit, vibrations can damage components or cause them to wear out more quickly,” MT notes.
Even though Cadillac President Steve Carlisle has insisted that the Corvette would get its cross-plane-crank Blackwing powerplant “over my dead body,” Motor Trend says the new design could just be a Chevrolet adaptation that would be upsized and switched to flat-plane-crank.
“It’s likely to have a lot in common with Cadillac’s engine, but with enough different to make it a game of semantics,” MT believes.
Chevy has already said the C8.R race car will be unveiled later this fall. Says Motor Trend: “When it does, take a good look under the engine cover, because what you see there is what you’ll be getting in the next Z06, and it won’t have pushrods.”
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