The horsepower wars are continuing to strengthen with Chevrolet's newest Corvette variant, the ZR1. The previous 500 horsepower benchmark was cleared by the remarkable Corvette Z06; however, under the pressure of the 600 horsepower Dodge Viper, General Motors has blown the 'Vette's engine by means of a large displacement supercharger.

The new engine, designated as the supercharged LS9 small-block V8, displaces 6.2 litres. Hand built in Michigan, this is the most powerful production engine ever from GM, supposedly pushing 100 horsepower per litre. The LS9 is similar in design to the new LS3 - a naturally aspirated 6.2 litre V8 for the Corvette - however there have been many tweaks to ensure durability under extreme forces, engine speeds, and temperatures.


Titanium intake valves, 5.5 centimetres in diameter, feed the ZR1's combustion chambers, which are hosts to a 9.1:1 compression ratio. Aluminum pistons with a 10.3 centimetre bore and a 9.2 centimetre stroke push high levels of power; there are many modifications allowing for the engine's extra intensity, including a higher capacity oil pump, high flow fuel injectors, and a reinforced crankshaft linking to the flywheel.

GM is suggesting that the Corvette ZR1 will have 620 horsepower, peaking at 6500 rpm, however exact specifications will not be available until March. Torque is to peak at 595 lb-ft, with 90 percent available from 2600-6000 rpm. Even at a low 1000 rpm, GM says 320 lb-ft are available.

Getting this power to the ground is a Tremec six-speed manual transmission with twin-26 centimetre clutches. In comparison, the Z06 utilizes a single, 29 centimetre diameter clutch. The gears are set at closer ratios to help quicken the ZR1's launch, while top speed runs can be made in sixth gear, over fifth gear runs in the Z06.

Performance figures for the ZR1 look promising. As the Z06 already demonstrates the run to 100 kilometres per hour in less than four seconds, the ZR1 will take closer to three.

Breathing life into the 6.2 litre small block V8 is a Eaton-developed 2.3 litre supercharger. This big blower, now in its sixth generation of design, runs at 10.5 PSI while utilizing a unique four-lobe design. Keeping temperatures down is a liquid-to-air charge cooling system, which lowers the air's heat by roughly 60 degrees Celsius. The intercooler is shielded by a special engine cover visible through a polycarbonate window in the hood.