Why Corvette C8.R Will Sound like Nothing Before It

Unique Sound

The C8.R Corvette finally broke cover recently, ripping around the track in its debut at the 2020 Rolex 24 Hours of Daytona. And it was there that we got to hear the new racer's brand new engine at full song. And oh, what a glorious-sounding thing it is. While it was common knowledge that this unique sound was derived from a flat-plane crank V8, Hot Rod was in Florida to get the scoop on exactly why the 5.5-liter mill sounds the way it does. Not to mention snap some great pics of the car in action.

Photos: Hot Rod  

Major Change

The C8.R's mill isn't your father's pushrod V8, that's for sure. It emits a higher-pitched exhaust note than the older car's deeper grunt, which is a massive change for an iconic American car. This can be directly attributed to the flat-plane crank design, of course, which utilizes a different firing sequence than the traditional cross-plane crank engines we're used to.

Photos: Hot Rod

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Limited Output

GM is still being very secretive with its new motor, which is why (unlike the production C8), the engine is hidden underneath its engine cover, not proudly on display. All they will say is that it's a 5.5-liter flat-plane crank, dual-overhead-cam V8 producing 500 hp and 475 lb-ft of torque. That may sound a little low, but that output is limited per class rules.

Photos: Hot Rod

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Slow Down

As Hot Rod points out, a cross-plane crank engine has two consecutive exhaust firings on one bank. Which helps it produce a deeper exhaust note, of course. But this isn't the most efficient setup in terms of exhaust scavenging. It also means they have to use large counterweights to properly balance the engine. These help keep the motor from rocking up and down. But they also keep rotational mass high, which makes for a slower-revving engine.

Photos: Hot Rod

>>Join the conversation about this raucous sounds of the C8R right here in the Corvette Forum!

Pros and Cons

On the flip side, flat-plane crank engines, no matter what the firing order is, will always alternate between banks. That makes for efficient exhaust scavenging without needing to have header primaries cross over from one bank to the other. This also means they don't have to use massive counterweights and can rev very quickly. The only downside? Flat-plane engines tend to have a noticeable secondary vibration, which is why manufacturers keep the displacement on the lower end.

Photos: Hot Rod

>>Join the conversation about this raucous sounds of the C8R right here in the Corvette Forum!

Dreaming of the Future

Overall, flat-plane crank engines enjoy some obvious benefits over cross-plane crank mills. And personally, we can't wait to see this new 5.5 land in a future production Corvette, perhaps the Z06. But for now, we'll just have to get our kicks from watching the C8.R in action, which we'll get to do a lot this coming racing season.

Photos: Hot Rod

>>Join the conversation about this raucous sounds of the C8R right here in the Corvette Forum!

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