Update your semi truck with top-tier engine performance, with the American Cylinder Head Cast Iron Engine Cylinder Head that ensures you're Ready for the Road Ahead. 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.