Racing Head Service (RHS) - 54903U

Engine - Bare Block - 4.125 in Bore - 9.250 Deck - Standard Main - 6-Bolt Mains - 1-Piece Seal - 6-Bolt Head - Aluminum - Natural - GM LS-Series - Each

This block has a 9.240 deck height with a 4.125 bore and a 5.87 cylinder sleeve length. Cylinder walls are Siamese cast with press-in cast iron sleeves. 12AN feeds for dry sumps. Aircraft-quality A357-T6 aluminum. 6-Head Bolt Design.

In recent years, LS engine technology has revolutionized the GM performance aftermarket. Gen IV engines have set a new standard for factory horsepower and torque. To meet the growing demand of today?s high performance engine builders and racing enthusiasts, engineers at RHSesigned an aluminum LS engine block for radical street and all-out racing applications.