Lightweight 4340 forged steel crankshaftSupplied with our Pro Series Lightweight I-Beam connecting rods with 7/16? ARP 2000 cap screws2618 Forged aluminum Platinum Series pistons with Premium Chrome Moly wrist pinsHorsepower range is 750 with the ARP 8740 and 1,500 with the optional ARP 2000 cap screws