Designed for the 1992-97 LT1 engines, these aluminum heads have specially designed 170cc intake and 60cc exhaust ports with increased valve sizes (1.94" intake, 1.55" exhaust) for maximum flow and performance. Combustion chamber volume is 54cc. Edelbrock Performer LT1 heads made 24 horsepower more than factory-stock LT1 heads and raised the peak power level by 500 rpm. Performer LT1 heads work with stock or aftermarket self-guiding roller rocker arms.