2021-04-04 | New Roads Magazine
The all-new Corvette Z06 delivers historic horsepower in a ride that’s as close to the track as you can get.
In the high-performance sports car world, there is no such thing as standing still. Sports car manufacturers around the world must constantly up their game to remain atop the conversation. Yet the Chevrolet Corvette, soon to mark 70 years since production began, seems to have a regular place there.
Case in point: Just three years after the introduction of the first production mid-engine Corvette, and with demand still high, comes the newest evolution of the Corvette. That, of course, is the all-new 2023 Z06. It was co-developed with the C8.R, which has already won two International Motor Sports Association (IMSA) GTLM Manufacturers Championships.
The Details Matter
All-new LT6 DOHC 8 with flat-plane crankshaft
“There was a niche following of customers,” says Corvette executive chief engineer Tadge Juechter, “that really pined for the immediate response, light weight, and the visceral feel that would exceed the previous-generation supercharged Z06. But what kind of powertrain would we need? The only way to do that is to create the highest-horsepower naturally aspirated production V8 that’s ever been done in world history. That’s what had to happen.”
And happen it did.
But the amazing thing is that the powertrain engineering team did it with a smaller displacement engine (5.5-liter versus 6.2).
Besides its all-new dual overhead cam valvetrain, the big secret of the Z06’s 5.5-liter engine is a flat-plane crankshaft. Compared to a V8 with a cross-plane crank, a flat-plane crank can rev higher, and for enthusiasts, that’s reason enough. Glorious sound and stunning performance are the payoffs.
HEAR THE DIFFERENCE
Z06 has four centrally mounted exhaust tips that appear to float in the center of the fascia, connected to four-into-two-into-one headers on each cylinder bank.
How does a flat-plane crank differ from the more typical cross-plane crankshafts? Flat-plane crankshaft rod journals — where the connecting rods attach — are 180 degrees apart when viewed from the end of the crankshaft, versus 90 degrees apart in a cross-plane crankshaft. That means the engine’s firing order alternates back-and-forth between the two banks of cylinders, helping increase exhaust airflow efficiency. The construction of a flat-plane crankshaft also requires less counterweighting, lowering inertia to help the engine quickly rev to 8600 rpm. Plus, a shorter stroke and wider bore help the engine rev faster.
“An engine of this nature is truly playing in the exotic space,” says Dustin Gardner, assistant chief engineer, LT6 engine.
“It is a low-volume, hand-built precision engine,” adds Gardner. “The biggest advantage of the flat-plane crank is that the mass of the engine that moves is much lighter. It allows the engine to accelerate to speed much more rapidly than a small-block.”
The exhaust system was completely reinvented, with four outlets grouped at the center of the rear fascia. Even the exhaust tips were given a parabolic shape to reflect more sound back to the driver. The result is a higher-pitched sound than a traditional V8.
What it all means is 670 horsepower, 460 pound-feet of torque, and an 8600-rpm rev limit.
Even though it is only 5.5 liters of displacement, the LT6’s power output exceeds the 650-horsepower number of the 6.2-liter supercharged engine powering the seventh-generation Z06.
OPEN AIR OR HARDTOP
Thanks to Corvette’s stiff structure, shared with the similarly robust Stingray, engineers were able to use the same suspension calibrations for the coupe and hardtop convertible versions of the Z06.
Closer than ever to the C8.R race car
The Z06 was created side by side with the C8.R. In fact, when the C8.R was certified for racing with its current engine, it was with the understanding that Chevrolet would eventually put that engine into a production car. Like a thoroughbred racing engine, the LT6 engine in the Z06 is hand assembled at a special facility in the Bowling Green, Kentucky, plant.†
For better road holding on the track, the Z06 sports wider front and rear fascias with larger tires and wheels — 21-inch wheels in the rear and 20 inches in the front, a full inch larger in diameter compared to the Stingray. Michelin® Pilot Sport® summer-only tires† are standard, good for 1 g of lateral acceleration capability on the skid pad.
The large side scoops on the Stingray were widened further on the Z06 to help the engine drink in even more air.
Z06 buyers who want the closest thing to a C8.R race car can check the box for the available Z07 Performance Package. This includes a high rear wing, an elongated front air dam, and front dive planes ahead of the front wheel wells, all for better downforce on the racetrack. While the Z06 braking system is fitted with six-piston front calipers and four-piston rear calipers, the Z07 Performance Package includes larger, carbon ceramic brakes designed for increased endurance for track usage.
The icing on the cake is available lightweight carbon-fiber wheels that save a total of 41 pounds of precious unsprung weight. The package also includes Michelin® Pilot Sport® Cup 2 tires developed especially for this car.
Lightweight yet strong-as-steel carbon fiber is also used throughout the Z06, including ground effects, the rear wing, steering wheel trim, gear shift, and paddles.
Those three special alphanumeric characters date back to 1963, when the split-window Sting Ray was introduced. “Z06 was a code for a track-oriented performance option” for the second-generation Corvette, says Juechter. “Only 199 were built. It wasn’t until the fifth generation that we brought it back and it became a brand unto itself.”
The original Z06 offered all the heavier-duty racing hardware that potential racers were seeking, plus a huge 36-gallon gas tank for longer endurance events. “It’s the most track-oriented Corvette that we do,” Juechter says. “During the fifth, sixth, seventh, and now eighth generation, we have moved the street car and the race car closer and closer together.”
The 1963 split-window Sting Ray initiated the Z06 production option. It proved its merit in #119 driven by Doug Hooper at the 1962 Riverside 3 Hours, grabbing first place.
The 2015 version featured a supercharger with 650 horsepower. And now, the 2023 Z06 is the first mid-engine iteration of this proud nameplate. Each model was the pinnacle of Corvette performance, highly sought by enthusiasts.
This eighth-generation Z06 has been tested extensively at both Le Mans and Nürburgring, as well as on the autobahns of Germany. The 2023 Z06 will be available in summer 2022, and thousands of buyers have lined up to put their orders in. Their world will never sound the same.
The Z06 name became a model name in 2001 as a lightweight fixed-roof coupe with a 385-horsepower engine equipped with a titanium exhaust. It was upgraded to a 405-horsepower engine in 2002. In 2006 it included a lightweight aluminum structure and had a top test track speed of 198 mph.
STORY: JERRY BURTON / PHOTOGRAPHY: CLINT DAVIS / HISTORICAL PHOTO COURTESY GM HERITAGE CENTER