C4 Used L98 Tuned Port Injection Engine Assembly 1985-1991

Corvette L98 Tuned Port Injection Information

In 1985, the L98 5.7-liter, small-block V-8 displaced 350 cubic-inches and had an overhead valve configuration with cast-iron blocks. The engine had a bore and stroke of 4.0 x 3.48 inches with a compression ratio of 9.0:1. The L98 was rated at 230 horsepower at 4,000 rpm with 330 foot-pounds of torque at 3,200 rpm. The Tuned Port Injection system improved performance by 30 percent over previous carburetor systems and showed a 20 percent improvement over the cross-fire injection system. TPI worked by injecting fuel into each cylinder. TPI was controlled by a mini computer called the (ECM) Electronic Control Module. In 1987, the L98 on the Corvette received roller hydraulic valve lifters, which boosted horsepower up to 240 at 4,000 rpm. The torque changed to 345 foot-pounds at 3,200 rpm and the compression ratio rose to 9.5:1. In 1988, the L98 was tweaked for the last time on the Corvette. Modified aluminum cylinder heads were inserted onto the engine, which allowed the engine to breathe better, and the camshaft was revised. The modifications boosted horsepower by 5. The revised L98 had an output rating of 245 at 4,000 rpm and the torque remained the same. Road and Track clocked the 1988 Corvette at 6.0 seconds in its 0 to 60 test. The 1990 & 1991 L98 engines received a slight increase in power, boosting engine performance to 250 horsepower and 350 foot-pounds of torque @ 3,200 rpm, thanks to the addition of an added air-intake speed density control system, a revised camshaft and an increased engine compression ratio of 9.5 :1 for 1990 and 10:1 for 1991 to end the L98 era.