Piston

During engine combustion, the fuel and air mixture is ignited by the spark plug while the intake and exhaust valves are closed. The resulting explosion expands and pushes down on the engine piston. This downward movement forces the crankshaft to turn, similar to when you push down on bicycle pedals with your feet to make the rear tire move. Engine pistons need to be strong enough to handle the heat and combustion that pushes against them. Whether a normally aspirated daily-driver engine, or an all-out high performance nitrous-powered dragster power plant, if you don't have the right piston, engine performance will suffer and damage will result.