ES1G is part of World Products' line of cast iron cylinder heads. The ES1G head is designed for use in street applications and features a 72cc combustion chamber and 205cc intake runners. The valve sizes for the ES1G are 2.02 inch intake, and 1.60 inch exhaust. The ES1G is also compatible with OE 4340 steel crankshafts and stock exhaust manifolds. World Products' ES1G is a great choice for budget-minded performance enthusiasts.