Tom had the opportunity to work on a turbo piston several weeks ago. On this particular piston the compression ratio needed to be lowered. Pistons are a basic part to all types of machinery that employ a reciprocating engine and are designed to work in harmony with the other components of the engine. Pistons sit in a cylinder and operate by transferring force to the crankshaft. If you have ever wondered why the tops of the pistons have an elevated ring around them, here is the answer.
The outside area of a piston is called the quench area. When machining a piston you need to be careful not to take to much of that outside area out. When the piston is in motion and going up under compression the quench area comes very close to the head and transfers a small amount of the heat out of the piston into the head in a matter of a split second. If the quench area has been machined down too much, it can cause the piston to over heat. This could lead to detonation. Sometimes this is the cause of an engine that has over heated.