What is the crown of a piston?

Answer 1

The piston crown refers to the top of the piston.

A piston can generally be divided into two sections (though the piston is a single piece). The lower part of the piston is called the skirt. The upper part, including the top of the piston that faces the valves and must handle the combustion of the fuel-air mixture, is called the crown. The piston crown must have the mechanical strength to withstand the forces of combistion, and must be made of materials that will withstand the heat of combistion. All this must come in a package that has limited thermal expansion so that the tolerances within the engine are tighter and performance is maximized.