2023 Chevy Corvette Z06 Brings 670 HP of Naturally Aspirated Fury
Corvette executive chief engineer Tadge Juechter is candid about the real reason why America’s sports car got a mid-engine layout: “When we went mid-engine, the justification for it wasn’t the standard car.” While the mid-engine architecture works great for the 10Best-winning Stingray, the bigger motivation for a new platform with the engine in the middle has everything to do with the 2023 Corvette Z06—a winged wide-body supercar aimed squarely at the enthusiast’s heart.
“The higher-horsepower cars benefit the most from getting all of that traction in the back,” Juechter continues. And with 670 horsepower, the all-new double-overhead-cam (DOHC) 5.5-liter V-8 is the highest-horsepower naturally aspirated V-8 ever installed in a production car, beating out the 622-hp 6.2-liter fire-breather that powered the 2014 Mercedes-Benz SLS AMG Black Series. The Z06 comes with wider tires and fenders and a screaming V-8. Go for the Z07 package and the tires get stickier and the wings get wicked.
If debuting a naturally aspirated engine in today’s turbocharged and electrified world sounds like Recaro suddenly coming out with a saddle, it’s likely you haven’t heard the Porsche 911 GT3’s 4.0-liter flat-six’s 9000-rpm call to prayer. On the last Z06 go-round, supercharging upped power, but Chevy heard a lot of feedback suggesting that the Z06 should return to the purity of the high-revving LS7 from the gen-six Corvette. Going naturally aspirated is for drivers who know the difference and crave a certain sound experience and a direct connection that turbos and hybrids can’t match. There’s no manual; Chevy didn’t go that far and is sticking with the eight-speed dual-clutch automatic. While we haven’t had a chance to drive the Z06 yet, we’ve heard the engine. It made the hair on our neck stand on end. If it doesn’t do the same to you, may we suggest you reach for Highlights for Children on your next visit to the dentist? —Tony Quiroga
Enter the LT6
Chevrolet insists that the Z06’s new LT6 engine is a clean-sheet design—and it is, for the most part. But there is one spec that carries over: the 4.4-inch bore center. This dimension, which defines the distance between the piston centers within a cylinder bank, is common to all Chevy small-block V-8s. Even the last DOHC engine in a Corvette—the C4 ZR1’s LT5, with its Lotus-designed head—had 4.4-inch bore centers.
Never mind that LT6 is an engine code shared with a short-lived 4.3-liter V-6 Oldsmobile diesel. The new LT6 is destined for greatness. In a General Motors first, every engine will be put on a dyno, run through a 20-minute break-in, then tested to make sure it’s working as advertised before being installed in a new Z06. Aside from an 8600-rpm redline, the interior is largely unchanged. John RoeCar and Driver
The engine is rated at 670 horsepower and 460 pound-feet of torque, with the horsepower peaking at 8400 rpm, right near the 8600-rpm fuel cut. That Ferrari V-8s also make peak power right at redline is no coincidence. In the LT6, more revs mean more power, and the engineering team will use every last rpm it can.
In an automotive world obsessed with electrification and efficiency, it’s bold for GM to develop a new engine with a short stroke and a fat bore. Cylinder dimensions are 104.25 millimeters by 80.0, netting a displacement of 5.5 liters. The compression ratio is 12.5:1. And for the engine nerds: The brake mean effective pressure is in excess of 1400 kilopascals.