Which type of engine component is primarily associated with a four-stroke engine like that in the Cessna 172?

A piston is the primary component associated with a four-stroke engine, such as the one found in the Cessna 172. In a four-stroke engine, the piston plays a crucial role in the engine's operation by converting the energy produced from fuel combustion into mechanical motion. The four-stroke cycle consists of intake, compression, power, and exhaust strokes, where the piston moves up and down within the cylinder to facilitate these processes.

During the intake stroke, the piston moves down, creating a vacuum that draws in the air-fuel mixture. Then, as the piston moves up during the compression stroke, the mixture is compressed to enhance efficiency. Upon ignition, the combustion of the mixture forces the piston back down during the power stroke, which is what ultimately generates the power to turn the crankshaft and propel the aircraft. Finally, during the exhaust stroke, the piston moves back up, expelling the exhaust gases.

Other engine components such as rotary valves, superchargers, and magnetos have specific functions in engine performance or ignition but do not fundamentally define the four-stroke cycle in the same way as the piston. For instance, a rotary valve is not typically a component found in four-stroke piston engines; superchargers are used