2009

ZR1 - King of The Hill

The 2009 Chevrolet Corvette ZR1 will be the most powerful and fastest production car ever produced by General Motors, with performance enabled by a new, supercharged 6.2L LS9 small-block V-8 engine.

Incorporating the engineering experience already found in the Corvette Z06's LS7 engine and the new-for-2008 6.2L LS3 of the Corvette, GM Powertrain is targeting 100 horsepower per liter for the LS9, or 638 horsepower, and approximately 604 lb.-ft. of torque

The enabler of the LS9's performance is a new, large positive-displacement Roots-type supercharger; with a unique four-lobe design; developed for the engine by Eaton. It is teamed with an integrated charge cooling system that reduces inlet air temperature for maximum performance. The LS9 represents the first of several new, supercharged small-block engines that will be introduced in GM vehicles in the near future, each using superchargers of similar design.

More than just its tremendous peak horsepower and torque numbers, the supercharged LS9 makes big power at lower rpm and carries it in a wide arc to 6,600 rpm. GM Powertrain testing shows the engine makes approximately 300 horsepower (224 kW) at 3,000 rpm and nearly 320 lb.-ft. of torque (434 Nm) at only 1,000 rpm. Torque tops 604 lb.-ft. at about the 4,000-rpm mark, while horsepower peaks at 6,500 rpm. The engine produces 90 percent of peak torque from 2,600 rpm to 6,000 rpm.

Heavy-duty and lightweight reciprocating components enable the engine's confident high-rpm performance, while the large-displacement Eaton supercharger pushes enough air to help the engine maintain power through the upper levels of the rpm band.

The LS9 is assembled by hand at GM's Performance Build Center, a unique, small-volume engine production facility in Wixom, Mich., that also builds the Corvette Z06's LS7 engine and other high-performance GM production engines.

The Corvette ZR1's LS9 engine is backed by a Tremec TR6060 six-speed manual transmission, with a twin-disc clutch system. It is based on the new-for-2008 TR6060 six-speed, but upgraded to handle the LS9's torque output and delivers improved shift quality.

The twin-disc clutch system provides exceptional clamping power, while maintaining an easy clutch effort. The system employs a pair of 260-mm discs, which spreads out the engine's torque load over a wider area, enabling tremendous clamping power to channel the LS9's torque. It also dissipates heat better and extends the clutch life (in normal driving).

Thanks to comparatively small plates, the twin-disc system enables similar disc inertia to the Corvette Z06, which has a 290-mm single-disc system, contributing to low shift effort and providing exceptionally smooth engagement and light pedal effort. In fact, the more powerful ZR1 has a pedal effort similar to the Z06.

ZR1-specific gearing in the transmission provides a steep first-gear ratio that helps launch the car. The car's top speed is achieved in sixth gear; a change from the fifth-gear top-speed run-outs in the manual transmission Corvette and Corvette Z06. The gears also are designed to balance performance with refinement. The angles of the gear teeth are optimized to provide both strength and quietness.