The most powerful car General Motors has ever built will soon hit the streets, packing 650 horsepower and 650 pound-feet of torque. It’s the new 2015 Chevrolet Corvette Z06, and it promises to be America’s fastest production car, in both coupe and convertible forms.
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Creating all of that power is a 6.2-liter LT4 supercharged V-8 engine, officially certified at the dual 650 mark. Peak power comes at 6,400 rpm, while peak torque arrives at just 3,600 rpm. While the horsepower curve looks like a financial analyst’s dream—always up and to the right—the torque curve is a much flatter, rising from 457 pound-feet to its peak, then gently descending back again as the engine’s RPMs range from idle to redline. Over 90 percent of peak torque (592 pound-feet) is available from 2,500 rpm to 5,400 rpm.
The LT4’s prodigious output has Chevy talking tough. “Torque is the pulling power of an engine and the LT4’s abundance of it at every rpm in the engine’s speed range helps the 2015 Corvette Z06 accelerate quicker and respond nearly instantaneously,” said Jordan Lee, chief engineer for Small Block engines. “It’s the very definition of power on demand.”
Fans of supercharged Corvettes will note that the Z06’s torque output eclipses even the last-generation ZR1—by about 7.5 percent. It has 12 more horsepower, too.
“It’s also worth mentioning that the LT4’s supercar performance numbers are achieved with an engine that is nearly the same size as the very compact LT1 engine introduced in the 2014 Corvette Stingray,” Lee said. “The power density of the LT4 makes it one of the smallest and lightest 650-hp engines in the industry.”
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Ford fans might counter with the example of the 2013 Mustang Shelby GT500, which rates an even lairier 662 horsepower and 631 pound-feet of torque from its own supercharged 5.8-liter V-8 engine, but Z06 aficionados will be quick to point out that their Bowtie-branded car will likely weigh at least 300 pounds less than the Blue Oval's beast once the final figures are released.
The motive force behind the LT4’s power output, aside from its 10.0:1 compression ratio, forged aluminum internal components, titanium intake valves, direct injection fueling, and the Rotocast A356T6 aluminum cylinder heads, is the Eaton R1740 TVS 1.7-liter supercharger rotating at up to 20,000 rpm. Stainless steel exhaust manifolds help cut weight, while a dry-sump oiling system helps ensure even lubrication even under hard cornering loads. The engine can be mated to either the standard seven-speed manual gearbox, or the new 8L90 eight-speed paddle-shift automatic, which Chevy says has been tuned to perform on par with competitive dual-clutch units.