The plane truth.
Next Corvette Z06 may get the C8.R’s flat-plane heart
Think what you will about the Corvette C8.R’s flat-plane howl; that same 5.5-liter DOHC V-8 will likely drop into the next Corvette Z06 in one form or another, and we have the FIA to thank.
The French sanctioning body writes the rulebook for one of the main race series in which Corvette races, and that rulebook, under which various dot-R ’Vette’s have raced at Le Mans, demands that engines must come from series production cars.
That’s the boring, regulatory background. The exciting part? The engine we heard trackside for the first time in the C8.R at Petit Le Mans is limited, per FIA rules, to 500 horsepower via an air restrictor. “It’s like breathing through a straw,” said Doug Fehan, Corvette Racing’s program manager. For those of us on this side of the pit wall, that’s excellent news; in the Z06, the as-yet-unnamed DOHC V-8 will be free-breathing and could well be force-fed by twin turbochargers.
Forced-induction or not, more air means more horsepower; the previous-generation Z06 pumped out 650 horsepower from its supercharged LT4, and it’s no stretch of the imagination that the C8 Z06 will outstrip that.
While you might assume race cars get the mostest of everything, FIA standards have meant that previous Corvette Racing cars have more in common with their contemporary Z06 brethren and less with the top-of-the-line ZR1s. Though the FIA regulations do aim to put a ceiling on Group-B levels of engineering wildness, the rules are meant to promote trickle-down tech advancements from racing to road cars. (To which we may soon say: thank you, FIA, for my next Z06.)
We knew the mid-engine moved signaled that Chevy had maxed-out the front-engine layout, and Corvette chief engineer Ed Piatek says this DOHC architecture implies the same ceiling reached on the beloved pushrod architecture. “Lower mass, more horsepower, quicker throttle response—that’s the benefit [of the flat-plane crank],” Piatek says. “You get this really fast, zingy engine response.
“There’ve been these snickers at using truck motors in our street cars, so when we got a clean sheet of paper and we knew what the homologation specifications were, we thought, why not take advantage of the opportunity and do a screamer?”
The flat-plane structure certainly comes with its downsides, most notably in the realm of second-order vibrations. Lower rotational inertia allows the C8.R’s powerplant to maximize the torque curve by hitting higher engine speeds more efficiently. However, the rev-happy, flat-plane design generates more lateral movement, rocking the engine.
Given the competitive, cloak-and-dagger nature of bringing an entirely new race car to track, Chevrolet remained tight-lipped about finer details, but we’ll be especially curious how Chevrolet approaches the problem. Balance shafts? Likely not. Lightweight connecting rods? In the race car, FIA regulations allow for connecting rods to be built of titanium-based alloys; in the street-going Z06, who knows what wizardry we may see.
However much the balance of performance irks teams, the FIA regulations often benefit customers and, frankly, make manufactures look good. Chevrolet boasts that the same aluminum frame undergirds the C7.R and the Z06, and that, for the first time, the double-duty frame would be built at the Bowling Green facility. And since the C7 sported direct fuel injection, the C7.R used the same system to hit the track.
Despite the fear of C8 production delay, Corvette Racing’s team manager Ben Johnson says he has no concerns about fulfilling the homologation requirements for C8.R to makes its track debut at the Rolex 24 at Daytona in January 25–26 of 2020.
We’re excited to see how this eighth-generation line of ’Vettes reshapes the Corvette legacy. The mid-engine layout and flat-plane variants certainly reposition the Corvette in comparison to any of its domestic rivals, if it even has any. We’re guessing that Corvette’s identity as a budget American performance car that can hang with the exotics in power and style is coming to the forefront.
Both street and track-exclusive ’Vettes are eyeing their across-the-pond rivals. What’s your prediction on the outcome?