The heart of the 2015 Corvette Z06 is the all-new LT4 6.2L supercharged V-8 engine, expected to deliver an SAE-certified 650 horsepower (485 kW) and 650 lb-ft of torque (881 Nm). To balance performance and efficiency, the LT4 leverages the same trio of advanced technologies introduced on the Corvette Stingray: direct injection, Active Fuel Management, or cylinder deactivation, and continuously variable valve timing.
These technologies - combined with the fuel-efficient multi-speed transmissions, aerodynamic design and lightweight construction - help make the new Z06 surprisingly fuel efficient.
To maintain the Z06's mass and performance targets, the LT4 engine was designed with a more-efficient, more-compact supercharger. Even with its integrated supercharger/intercooler assembly mounted in the valley between the cylinder heads, the engine is only about one inch (25 mm) taller than the Corvette Stingray's LT1 engine - while delivering nearly 37 percent more horsepower and 40 percent more torque.
A new 1.7L supercharger spins at up to 20,000 rpm - 5,000 rpm more than the supercharger on the Corvette ZR1's engine. The rotors are smaller in diameter, which contributes to their higher-rpm capability - and enables them to produce power-enhancing boost earlier in the rpm band. That boost is achieved more efficiently via a more direct discharge port that creates less turbulence, reducing heat and speeding airflow into the engine.
The LT4 engine also has 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 that offer greater structure at higher temperatures
Lightweight aluminum balancer
Standard dry-sump oiling system with a dual-pressure-control oil pump.
Seven-speed manual and new eight-speed automatic transmissions
The supercharged LT4 is offered with a standard seven-speed manual transmission with Active Rev Match, or an all-new 8L90 eight-speed paddle-shift automatic transmission designed to enhance both performance and efficiency.
The seven-speed manual incorporates rev-matching technology for upshifts and downshifts. This driver-selectable feature can be easily engaged or disengaged via paddles on the steering wheel. The seven-speed is used with a new dual-mass flywheel and dual-disc clutch, which deliver greater shift quality and feel through lower inertia.
The eight-speed automatic is tuned for world-class shift-response times, and smaller steps between gears keep the LT4 within the sweet spot of the rpm band, making the most of the output of the supercharged engine for exhilarating performance and greater efficiency.
For performance driving, the transmission offers full manual control via steering wheel paddles, and unique algorithms to deliver shift performance that rivals the dual-clutch/semi-automatic transmissions found in many supercars - but with the smoothness and refinement that come with a conventional automatic fitted with a torque converter.
In fact, the 8L90's controller analyzes and executes commands 160 times per second, and wide-open throttle upshifts are executed up to eight-hundredths of a second quicker than those of the dual-clutch transmission offered in the Porsche 911.
Featuring four gearsets and five clutches, creative packaging enables the GM-developed eight-speed automatic to fit the same space as the six-speed automatic in the Corvette Stingray. Extensive use of aluminum and magnesium make it more than eight pounds (4 kg) lighter than the six-speed. Along with design features that reduce friction, the 8L90 is expected to contribute up to 5-percent greater efficiency, when compared with a six-speed automatic.