Equip your semi truck to be Ready for the Road Ahead , with the American Cylinder Head Cast Iron Engine Cylinder Head that provides top-tier engine performance. Due to its advanced design, this replacement component is able to directly seal off the combustion chamber of an engine, efficiently burning its fuel to increase performance, fuel efficiency, and overall reliability. Constructed to sit above an engine block alongside the head gaskets. FleetPride is your First Click in Heavy Duty .