Lightweight 4340 forged steel crankshaft4340 Forged steel H-Beam connecting rods with 7/16? ARP 8740 or optional ARP 2000 cap screws*2618 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