In any internal combustion engine the pistons have to withstand the tremendous heat and pressure of combustion. The piston rings must also endure this extreme strain and temperature while sealing the pistons to the cylinder walls and providing sufficient oil control. Finally, the connecting rods must persevere through the pounding as they transform the pistons’ reciprocating motion into the rotational movement of the crankshaft.
These stresses are amplified in a high horsepower performance engine, which typically has higher compression, operates at higher RPM, and may have power adders like nitrous oxide, a turbocharger or supercharger. It goes without saying that stronger pistons, rings, and connecting rods are necessary, but at the same time these parts should be as light as possible to allow the engine to rev freely, while creating very little frictional power loss.
Performance piston material ranges from cast hypereutectic (an alloy with a high silicon content for strength) aluminum that is fine for mildly modified street engines to forged and billet aluminum for high horsepower and racing applications. All pistons are designed and precision machined for superior strength with light weight. Factors that affect piston selection include bore size, compression ratio, and valve clearance. Most pin bores are designed for floating pins retained by clips. Many pistons come with coatings to reduce skirt scuffing, improve surface wear resistance, and reflect heat, which improves durability.