VETTE FANS RECEIVE HISTORIC POWER BOOST
PONTIAC, Mich. - The 2002 5.7-liter Overhead Valve (OHV) LS6 engine for the ZO6 Corvette will be rated at 405 horsepower. The increase of 20 horsepower equates to 71 horsepower per liter in this 5665 cc engine - the highest output yet in a Gen III small-block.
The new LS6 V8 delivers 405 horsepower at 6000 rpm and 400 lb-ft of torque at 4800 rpm. To achieve this additional power the engine received modifications including a revised air cleaner housing, low restriction Mass Air Flow (MAF) sensor, lightweight valves, higher lift camshaft and an exhaust alteration.
The component modifications that enable the additional 20 horsepower and 15 lb-ft of torque (compared to 2001) all focus on getting more air into and out of the engine. Increasing the volume of air in and out ultimately creates more power.
Air first enters through the air cleaner housing. The new air box opening to the air cleaner increases by approximately 6.65 square inches (43 cm2). This additional Volume contributes to more horsepower.
The new MAF sensor no longer has pre-sensor grid work known as air channels. Induction air thus flows less restricted through the mass air flow sensor and into the intake manifold.
Gases flowing into and out of the combustion chamber pass by new hollow stem valves (shown at left). The stems of the exhaust valves are filled with a liquid sodium alloy. Since the exhaust valves operate at a much higher temperature than the intake valves, the liquid alloy enables better transference of heat from the exhaust valves to the valve guides and then to the engine coolant. The valves reduce valvetrain mass by approximately 368 grams. This lighter weight allows the valves to keep contact with the cam at higher speeds.
The new cam profile is the greatest contributor for the increased power. The new profile allows the intake and exhaust valves to open .7 mm further. This key change enables more air to be pumped in and out, which equates to more power. Each camshaft is induction hardened and straightened to an accuracy of ten microns to ensure it spins true in the engine. All 16 lobes are inspected using opto-electrical technology with submicron level precision.
For 2002, the ZO6 will eliminate the use of dual pup catalytic converters found immediately downstream from the exhaust manifolds. Eliminating these converters allows for increased exhaust flow out of the engine. The under floor catalytic converters have been modified to make up for the pup converters and still meet NLEV emissions standards.
With 405 horsepower the LS6 will match the highest peak power level of the legendary 5.7-liter DOHC LT5 which powered the ZR1 Corvette from 1990-1995. For OHV V8 fans and the engineering community this is a significant milestone.
The LS6 was made possible by using the Gen III architecture introduced in the 1997 LS1. This new small-block variation included features such as a deep skirt aluminum block, cross-bolted mains, internally balanced crank, electronic throttle control and coil-near-plug ignition. The Gen III small block retained the simplicity of OHV design and built in appropriate advanced engine technologies.
Commenting on the new power level Assistant Chief Engineer John Juriga said: "With the advent of the '02 OHV LS6, GM Powertrain continues to prove its ability to deliver power and performance in a small package and exceed customer expectations."