Yahoo Autos 2025 Chevy Corvette ZR1's V-8 Is More Than a Z06 Engine with Turbos
The 2025 Chevrolet Corvette ZR1's twin-turbo 5.5-liter V-8 is designated LT7.
With 1064 horsepower, the LT7 is the most powerful production Corvette engine ever built.
The LT7 has a number of unique parts, but it also shares a few with the Corvette Z06's LT6 V-8.
The 2025 Chevy Corvette ZR1's LT7 V-8 is more than just a Corvette Z06 engine, or LT6, with two turbos. Sure, the pair share a basic relationship, including their displacement, block structure, and—for all intents and purposes—forged-steel flat-plane crankshaft, but there's still much that separates the two twin-cam V-8s in this premium sports car.
LT7 vs. LT6
Compared with the LT6, the LT7 features beefier connecting rods and larger pins, as well as a distinct head casting with a more boost-friendly—nominal boost pressure is 20.0 psi—exhaust layout that complements stouter pistons, replete with topology specific to the LT7, netting a compression ratio of 9.8:1, down from the 12.5:1 ratio of the naturally aspirated LT6.
Thanks to the head casting's unique design, Chevy has managed to integrate both port and direct fuel injection into the LT7. The LT6, on the other hand, is a direct-injection-only setup. The LT7 generally relies on some combination of the two systems; however, it employs all 16 injectors at full tilt and uses just the port injectors at idle as a way of keeping things hushed.
Lifting off the accelerator activates an anti-lag system that adjusts the engine's variable valve timing, closes the turbos' wastegate, and opens the throttle to keep air moving through the impellers. This feature helps maintain boost, and improves engine response once you get back on the gas.
The LT7's 1064 horses and 828 pound-feet of torque (800 pound-feet of which is available at just 3000 rpm) ultimately make their way to the tarmac via the rear end. To handle this additional load, Chevy increased the rear wheels' five-bolt pattern from the 120-millimeter figure of lesser Corvettes to 150 millimeters for the ZR1.
A Tougher Transmission
The automaker also strengthened the eight-speed dual-clutch automatic transmission. Although it retains the same gear ratios as the Z06, the ZR1's drivetrain adopts physically wider gears, beefier input and output shafts, a reworked lubrication system designed to prevent overheating during sustained high-speed driving, and shot-peened differential gears.
Chevy also limits the engine's torque when operating in the transmission's first two gears. This serves both as a preservation measure and a necessity. Otherwise, it would be nearly impossible to get the LT7's power to the ground without turning the rear tires into balls of burnt rubber and smoke. It's a small price to pay in the name of all-out power.
Mike Sutton contributed to this article.
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