GM Details 650-hp Corvette Mill

The 2015 Corvette Z06 will be the most powerful production car ever made by General Motors Co. when it goes on sale in October.

The car will be propelled by a supercharged version of Chevrolet's LT4 6.2-liter V-8 engine that makes 650 hp and 650 lb-ft of torque. Output is delivered to the rear wheels through a 7-speed manual or all-new 8-speed automatic transmission.

The LT4 delivers 457 lb-ft of torque just above idle and 625 lb-ft at 2,800 rpm, according to GM. Peak torque is 40% greater than the previous-generation 7.0-liter LS7 engine and 8% more than last year's supercharged ZR1.

The LT4 engine shares its basic small-block architecture with the naturally aspirated engine in the standard Corvette Stingray's LT1 6.2-liter V-8. But the LT4 is equipped with special rotocast aluminum cylinder heads that are stronger than conventional heads. It also gets lightweight titanium intake valves, forged power metal connecting rods and forged aluminum pistons.

The engine is fitted with a stainless steel exhaust manifold and aluminum balancer, both of which weigh less than the units found on the LT1 engine. Direct injection enables an unusually high 10.0:1 compression ratio.

The LT4 is fitted with a 1.7-liter supercharger that is more compact than the one used on the ZR1 engine. The unit also spins at speeds as great at 20,000 rpm, one-third faster than the ZR1's system.

GM notes that the new engine is almost as compact as the LT1 powerplant that debuted in the 2014 Corvette Stingray. The company says the LT4's performance matches or exceeds that of the 560-hp, 6-cylinder engine in the Porsche 911 Turbo S sports car or the 730-hp, V-12-powered Ferrari F12 Berlinetta.

GM will produce LT4s at its engine plant in Tonawanda, N.Y., and at the Corvette assembly plant in Bowling Green, Ky.