15. Pistons and Rings

The piston remains one of the most challenging components to successfully design, and is certainly quite critical to the performance and durability of the engine. The root of the challenge lies in the piston’s role as the moving combustion chamber wall. It is thus directly exposed to the severe conditions of the combustion chamber, and must manage the work transfers between the combustion gases and the connecting rod. Further challenges implied by this role include the necessity of maintaining a combustion seal at this moving boundary, under a wide variety of operating conditions; the need to provide adequate lubrication and minimal friction and wear at an elevated temperature, and under continually starting and stopping conditions; and the requirement of managing the reciprocating forces as well as secondary forces resulting from the pivoting motion at its pin to the connecting rod.