GM Big Block V6 Engine; 8.9L/ 540 Cubic Inch; Automotive; 615 Horsepower/ 579 Foot Pounds of Torque; Cast Iron Block/ Aluminum Cylinder Heads; 8.5:1 Compression Ratio; 4.5 Inch Bore/ 4.25 Inch Stroke; Internally Balanced; With Cylinder Heads/ Forged Steel Crankshaft/ Forged Pistons/ Solid Roller Camshaft/ 4 Bolt Main Block/ 1 Piece Rear Main Seal/ Forged H-Beam 6.385 Inch Connecting Rods/ Valve Covers/ Oil Pan/ Timing Cover/ Roller Rockers With Stud Girdles/ SFI Rated Dual Keyway 8 Inch Balancer