General Motors has just released the details of the all-new 2015 Chevrolet Corvette Z06, their most powerful production car to date and one of the very few supercars in the United States that is capable of more than 600 horsepower.

The Z06 is powered by an LT4 supercharged 6.2L V-8 engine that is 659 PS (SAE-certified at 650 horsepower) at 6,400 rpm and with 881 Nm torque at 3,600 rpm.

“The LT4 Small Block sets a new benchmark for power and torque at GM.  The engine also puts the new Corvette Z06 on par with the most powerful supercars offered in America, while delivering performance with impeccable manners that make it suitable for daily driving,” said Steve Kiefer, vice president, GM Powertrain Engineering.

Low-end torque is what differentiates the LT4 from other supercar engines.  It produces 619 Nm just off idle and 847 Nm at only 2,800 rpm.  To put it in perspective, the V-12-powered Ferrari F12 Berlinetta produces 28 percent less torque even though it offers 12 percent more horsepower and its peak torque isn’t achieved until 6,000 rpm.  The LT4 on the other hand maintains 90 percent of its peak torque, or 802 Nm from 2,500 to 5,400 rpm.

Compared to a Porsche 911 Turbo S, the LT4 offer 90 more horsepower and 182 Nm of torque.

Supercar engine power comparison

“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.  It’s the very definition of power on demand,” said Jordan Lee, chief engineer for Small Block engines.

Corvette LT4 engine

The Z06’s new engine is so good it produces 244 Nm more torque than the 7.0L LS7 engine and 7.5% more than the supercharged 2013 Corvette ZR1.

When it hits 3,200 rpm, the new LT4 surpasses the LS7 by 252 Nm of torque.  HP-wise the LT4 is 29 percent greater than the LS7’s 505 horsepower, and 12 horses more than the ZR1’s LS9 engine.

“The new LT4 engine builds on the design strengths of our previous supercharged engine and leverages the technologies introduced on the Corvette Stingray – direct injection, cylinder deactivation and continuously variable valve timing – to take Corvette performance to an all-new plateau.  Our new, very compact supercharger also helps the engine make power more quickly, and perhaps more importantly, it helps produce more torque earlier in the rpm band.  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,” said Lee.

The new LT4 engine is based on the same Gen 5 small block foundation as the Corvette Stingray’s LT1 6.2L naturally aspirated engine, incorporating several unique features designed to support its higher output and the greater cylinder pressures created by forced induction, including:

  • Rotocast A356T6 aluminum cylinder heads that are stronger and handle heat better than conventional aluminum heads
  • Lightweight titanium intake valves
  • Machined, forged powder metal steel connecting rods for reduced reciprocating mass
  • High 10.0:1 compression ratio – for a forced-induction engine – enhances performance and efficiency and is enabled by direct injection
  • Forged aluminum pistons with unique, stronger structure to ensure strength under high cylinder pressures
  • Stainless steel exhaust manifolds and an aluminum balancer that are lighter than their LT1 counterparts
  • Standard dry-sump oiling system with a dual-pressure-control oil pump.

With smaller rotors, new 1.7L supercharger spins at up to 20,000 rpm – 5,000 rpm more than the supercharger on the Corvette ZR1’s engine allowing it to produce power-enhancing boost earlier in the rpm band. That boost is more instantaneous due to a more direct discharge port that creates less turbulence, reducing heat and speeding airflow into the engine.

“The Small Block’s cam-in-block design heritage has always enabled very high performance and responsiveness in a small, compact package – an attribute amplified by the performance of our new supercharger’s design,” said Lee.

The LT4 is matched with a standard seven-speed manual transmission or an all-new, paddle-shift eight-speed automatic transmission that is a first in the Z06 making it one of the few cars this powerful to offer the choice of a conventional manual transmission or an eight-speed automatic.

The 2015 Corvette Z06 goes on sale in North America, fourth quarter of 2014.