How can twelve cylinders take turns supplying power during the same two crankshaft revolutions?
Each cylinder needs 720° of crankshaft rotation to complete intake, compression, power and exhaust. This generic model offsets twelve cycle starts evenly around those two turns. Scrub the crank angle: the next cylinder begins its illustrated power stroke every 60°, while its piston remains linked to a rotating crank pin through a fixed-length rod.
Twelve evenly distributed four-stroke cycle starts divide 720° into 60° intervals. The smooth sequence comes from overlap between cylinders, not from a single cylinder completing its cycle faster.
In this evenly phased twelve-cylinder four-stroke model, how far does the crankshaft turn between successive illustrated power-stroke starts?
Orbit the paused model. The 60° bank angle is a declared generic layout choice. It makes the two rows visible; it does not identify a manufacturer or a specific V12.
Count the power starts
Set the crank to 60°. The next labelled cylinder has begun its power stroke. Twelve evenly spaced starts in a four-stroke 720° cycle give 720 ÷ 12 = 60°.
Follow one linkage
Show the left bank and scrub through the cycle. A piston’s blue body stays in its bore, its pale rod maintains one length, and the crank pin travels in a circle.
Separate cycle timing from real valve timing
Turn off the valve overlay. In this lesson a valve opens only over its matching ideal stroke. Real engines use opening and closing lead/lag, overlap and many design-specific choices.
The main parts
Cylinder block
The central casting supports two angled banks. Its dimensions are illustrative rather than a drawing of one engine.
Cylinder heads
Heads close the cylinders and carry the simplified intake and exhaust valve locations.
Crankshaft and journal planes
The orange shaft rotates once per displayed 360°. The visible journal planes give each illustrated cylinder a phase; this is a teaching kinematic layout, not a manufacturing drawing.
Pistons
Blue pistons are constrained to move along their angled cylinder bores.
Connecting rods
Each pale rod keeps a fixed length between its piston and the rotating crank pin.
Valves
Blue intake and graphite exhaust valves lift only during their matching simplified strokes.
Intake manifolds
Blue runners are original illustrative geometry. This model does not calculate mixture flow.
Exhaust manifolds
Graphite runners collect from each bank. They are not a thermal, acoustic or pressure model.