Engine Room · Demo
One crank angle drives everything — scrub it, run it, or take the tour.
How a four-stroke works
Suck, squeeze, bang, blow. Over four piston strokes the engine draws in a charge, compresses it, burns it so the hot gas shoves the piston down, then pushes the spent gas out. Each stroke is one half-turn of the crank — so a full cycle is 720°, two revolutions, with only one of the four strokes actually producing power.
The camshaft turns at exactly half crank speed, because the valves must act once per cycle while the crank turns twice. The spark fires a little before top dead centre — flame takes time to cross the chamber, so lighting early puts the pressure peak just after TDC, where it pushes hardest. And in engineer mode the PV chart in the rail shows the deepest idea of all: the area enclosed by the pressure–volume loop is the work each cycle delivers.
Idealised model. The PV loop is an Otto-cycle approximation, not a combustion simulation — the geometry and timing are real; the thermodynamics are a clean teaching idealisation.