What is the term for the distance a piston travels in a cylinder? The answer is stroke. More precisely, the stroke length is the distance the piston moves between top dead center and bottom dead center. The piston’s connecting rod transfers this motion to the crankshaft, turning the piston’s back-and-forth movement into rotation.
Stroke is also used for one phase of an engine cycle, such as the intake stroke, compression stroke, power stroke, or exhaust stroke. That double meaning can cause confusion: “stroke” may describe either a distance or a stage of operation, while “stroke length” specifically describes the measurement.
Engine designers consider stroke alongside bore, the cylinder’s internal diameter. Bore and stroke determine the displacement of each cylinder, so a long-stroke engine and a short-stroke engine with the same bore can have different capacities. A piston’s stroke is determined by the crankshaft’s crank throw; one complete crankshaft revolution moves the piston through one full stroke in each direction.