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Originally posted by Shaggin Wagon
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Bingo! I’m right there with ya -
Best comment ever on this news:
Feels like Chevy has been building up an Uno hand of draw-4 cards and they just played 'em all at once. No mercy.
Source: The C8 Corvette Z06 is Getting a Flat-Plane-Crank Twin-Turbo V-8!
You've heard the rumors and you've seen the leaked CAD drawings. The car world has been speculating about overhead cams and turbochargers and flat-plane cranks in the backs of C8 Corvettes for months now, but we've confirmed with a deep source on the Corvette team that the upcoming C8.R race car and, more crucially, the C8 Corvette Z06 will be powered by a flat-plane-crank twin-turbo dual-overhead-cam V-8.
"Everyone thinks it will be a small block, but it won't be," said our source. "Listen to the race car."
We did, and if you've ever seen the current C7.R car live, you know the roar of the pushrod LS7.R engine is unmistakable. Compare the above video, which shows a camouflaged C8.R testing at Sebring, to the one below. 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.
That last part helps explain why Chevrolet would do this. After all, Corvette Racing has won the 24 Hours of Le Mans eight times in 21 attempts with pushrod engines. As with the move to a mid-engine layout, the switch to a flat-plane crank is all about performance.
Consider the advantages. Flat-plane-crank engines have smaller, lighter crankshafts which can spin up faster than cross-plane-crank engines and lose less power to rotational inertia. The change in firing order also allows for better exhaust scavenging than a cross-plane crank. Exhaust scavenging, the method of pulling the last exhaust gases out of a cylinder faster using reflected pressure waves, improves performance and combustion efficiency—both crucial in racing.
Of course, flat-plane cranks have a big disadvantage in V-8 engines: balance. The whole reason Cadillac engineered the cross-plane crankshaft for V-8 engines back in the 1920s was to smooth out the engine. While cross-plane-crank V-8s are naturally balanced due to the order in which the pistons rise and fall in the block, flat-plane-crank V-8s have only half their vibrations cancelled out naturally, and the vibrations only get worse as engine speeds increase. Because the vibrations are caused by the movements of the pistons themselves, lightweight pistons and short strokes can help reduce (but not eliminate) the vibration of a flat-plane-crank engine. Aside from being annoying in the cockpit, vibrations can damage components or cause them to wear out more quickly.
Chevrolet, clearly, has calculated the performance advantage of lightening the rotating assembly and improving scavenging are worth the expense of designing a new engine, which explains the flat-plane crank. Why not a flat-plane crank pushrod engine, though? While it's mechanically possible, there's no advantage. Exhaust scavenging works better the faster an engine spins, and getting high RPM out of an engine requires a robust valvetrain. Even the best pushrod engine, the mighty LS7, maxxes out at 7,000 RPM. At higher engine speeds, flex in the valvetrain hurts precision and stability, which hurt performance. Ford's 5.2-liter Voodoo flat-plane crank V-8 doesn't spin to 8,250 RPM because of the crank, it's because of the advanced dual-overhead cam valvetrain.
That explains the flat-plane crankshaft and blasphemous dual-overhead cams, but just keeping up with Ford doesn't explain the turbos. Le Mans does. Le Mans' sanctioning body, the ACO, uses a formula called "Balance of Power" to attempt to level the playing field between different engine types and sizes, and for the past two years it's favored turbocharged engines from Ford and Ferrari to Corvette's detriment. Critically, Balance of Power can be adjusted simply by changing the maximum boost pressure of a turbocharged engine, whereas the naturally aspirated C7.R is forced to breathe through CNC-machined metal intake restrictors which have to be made from scratch.
Where would Chevrolet get such an engine? Why, from Cadillac, of course. Not quite, though. Even though Cadillac's new 4.2-liter twin-turbo DOHC Blackwing V-8 is built at the Corvette's engine plant in Bowling Green, Kentucky, GM has been adamant it's exclusive to Cadillac. How exclusive? Cadillac President Steve Carlisle told us Corvette would get it "over my dead body" and even Corvette champion and GM President Mark Reuss has said the engine hasn't even been test-fit in the C8 because it's a Cadillac engine.
Carlisle and Reuss may be splitting hairs, though. While the Z06 and C8.R's engine may not simply be a Blackwing with the wick turned up, it's likely to have a lot in common with Cadillac's engine but with enough different to make it a game of semantics. For starters, the Blackwing is a cross-plane-crank engine, so that would have to change. More critically, the Blackwing is a hot-vee design, a reverse-flow engine which puts its turbochargers in the valley between the heads rather than hanging off the sides of the engine. The leaked CAD drawings of a supposed twin-turbo DOHC C8 engine clearly show a traditional design with outboard turbos and the intake in the valley. At minimum, the Blackwing's crankshaft and heads would need to change, and that's a huge amount of work.
It doesn't necessarily mean starting over from scratch, though. The Blackwing was designed, in Cadillac's words, to be a "compact, mass-efficient" design which emphasized power-density and packaging, both important in the C8's small engine compartment. To share development costs, it's possible the C8 motor could use the Blackwing's block, and much of what was learned in developing the Blackwing's heads could be reused in the reconfigured Corvette heads.
There's one more change that would have to be made: bore. The Blackwing is an under-square engine—its stroke is longer than the diameter of its cylinder bores. Good for reliability and torque, bad for high-RPM performance. All modern flat-plane-crank V-8s, from Ford to Ferrari to McLaren, use over-square engines to reduce piston speed and quell those nasty flat-plane vibrations. Assuming Chevrolet doesn't change the stroke, the Blackwing would need to be bored out, increasing the displacement.
Don't expect a 5.5-liter displacement, though. Many outlets have tossed this number around without any basis. It may have come from the C7.R's engine, which is restricted by IMSA racing rules to 5.5 liters, and the old rule states "there's no replacement for displacement." Except there is. It's called forced induction, that's where the turbos come in. More important than that, though, larger displacement (bigger bores and longer strokes) means bigger vibrations, which is why it was so shocking to see Ford launch a 5.2-liter flat-plane-crank V-8. There's a reason Ferrari's flat-plane-crank twin-turbo DOHC V-8 is 3.9 liters and McLaren's is 3.8. Expect the C8's displacement to grow from the Blackwing's 4.2 liters, but fall well short of the 5.5-liter number that's been thrown around. The number of issues Ford has had with Voodoo engine failures alone should dispel any notion of Chevrolet going to an even larger displacement.
According to Chevrolet, the C8.R race car will be revealed sometime this fall. 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.
And then there are the rumors that a ZR1 model could have AWD with electric motors up front...Comment
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I've got to load and unload a few so far. They're pretty badass!Comment
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I"ll give it to Chevy as they did the C8-R right. Ford really fuck up the Ford GT with a twin turbo V6. They should have done a twin turbo 5.2L Voodoo from the GT350. Real car guy's want a V8 no matter how impressive the V6 Ecoboost is.Comment
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No they dont. Guys that can't let go of a bygone era and think they're real car guys are the only ones stuck on V8s.Originally posted by cyclonescott View Post
F1 has been V6 to V12...and I'd consider every single one of those guys car guys. IndyCar is V6 too.
Real car guys are able to appreciate a car without needing it to have a set number of cylinders.Comment
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Which one sounds better?
I daily a GT350. Trust me, it wouldn't be the same car with a V6.Comment
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Oh I certainly agree on sound...I was even pissed when the screaming V8s were replaced with whisper quiet hybris v6s in f1.
But a real car guy doesnt think theres only 1 acceptable engine.Comment
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That is not why there is such a push to go to small displacement engines. That's the propaganda of the the europhiles and asiaphilesOriginally posted by Ruffdaddy View Post
A big reason for the move to v6 is because of Europe's regulations and taxes on the engine's displacement size along with the tightening environmental controls so the mfrs wanted to be able to utilize that tech in the productions cars.
which as a result has gave us turbo and superchargers on so many production cars so they can beat the luxury displacement tax, fuel and pollution standards, while producing power numbers that keeps the consumer happy. Well that is until somebody tries to find a vehicle that can tow a modern car (5000 lbs)Comment
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When did I say what the push for small displacement was?Originally posted by John -- '02 HAWK View Post
I know its intended for manufacturers to make their racing programs more road car relevant. Why else would mercedes spend $400+ MM a year on F1 if it never benefited the corporate R&D strategy?
Designing cars around racing regs has been going on for over 50 years....and those regulations have started to lead to some awesome tech in recent times.Comment
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All these cars are nice and I still cannot afford themOriginally posted by Da PrezOriginally posted by VETTKLR
Cliff Notes: I can beat the fuck out of a ZR1
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Exactly, yet another example of someone who's not a target buyer bitching about a car they would never buy anyway. Last I checked, there aren't any Ford GT's sitting at a dealership unsold.Originally posted by Juiced4v View Post
The little stock turbo 6 in my X4 is puts down more power than the bored H/C/I V8 that was in my '98 GT back in the day.Comment
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Only in Detroit...
2020 C8 Corvette Wheels Jacked, Car Left on Blocks.
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Well it is DetroitOriginally posted by Trip McNeely View Post2020 C8 Corvette Wheels Jacked, Car Left on Blocks.
https://www.motortrend.com/news/2020...stolen-blocks/Comment
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