Description: Affordable horsepower from an iron workhorse. Here from GM Performance Parts are these replacement partial engines for all ZZZ through ZZ4 series crate engines. These partial engines consist of cast iron 4-bolt mains with 1-piece rear main seals. Inside you have Forged 1053 steel internally balanced crankshafts, 5.7 in. powdered metal connecting rods with hypereutectic flat top pistons with offset pins.(more)

Description: Affordable horsepower from an iron workhorse. Here from GM Performance Parts are these replacement partial engines for all ZZZ through ZZ4 series crate engines. These partial engines consist of cast iron 4-bolt mains with 1-piece rear main seals. Inside you have Forged 1053 steel internally balanced crankshafts, 5.7 in. powdered metal connecting rods with hypereutectic flat top pistons with offset pins. These are the same pins used in Corvette LT1 engines. Also included are rings, bearings and brass freeze plugs already installed. Does not include camshafts, timing chains. Sprockets, front covers, oil pumps, oil pans, balancers, or flex plates. Compression ratios depend upon the combustion chamber size of the cylinder heads you use. Approximate compression ratios would be 10.0:1 with 58cc, 9.8:1 with 62cc, 9.6:1 with 64cc, and 8.5:1 with 76cc cylinder heads. (minimize)