Piston is a reciprocating part in the cylinder block of automobile engine. The basic structure of piston can be divided into top, head and skirt. The top of the piston is the main part of the combustion chamber, and its shape is related to the type of combustion chamber selected.

Most gasoline engines use flat top pistons, which has the advantage of small heat absorption area. There are often various pits on the top of the piston of diesel engine, and their specific shape, position and size must meet the requirements of mixture formation and combustion of diesel engine.

Source: @e_paternoster_artist