A given power stroke can last no more than 180 degrees of crankshaft rotation, so the power strokes of a four-cylinder engine are sequential, with no overlap.

However, it was decided to arrange that each cylinder's exhaust piston would lead its inlet piston by 20 degrees of crankshaft rotation.

Each stroke consists of 180 degree rotation of crankshaft rotation and hence a four-stroke cycle is completed through 720 degree of crank rotation.

Rather than firing every 120 of crankshaft rotation, the cylinders would fire alternately at 90 and 150 , resulting in strong harmonic vibrations at certain engine speeds.

The four strokes refer to intake, compression, combustion (power) and exhaust strokes that occur during two crankshaft rotations per power cycle.

Honda unveiled a revolutionary idea with a 1992 V4 that was timed to fire all four cylinders within 65-70 degrees of crankshaft rotation - the so-called "Big-Bang" engine.

The reciprocating motion of the pistons is translated into crankshaft rotation via connecting rods.

Each cylinder fires a power stroke every 120 of crankshaft rotation.

Whereas the actual displacement is 3924cc if all cycles are counted during the 1080 degrees of crankshaft rotation.

All cylinders have completed their cycles within 720 degrees of crankshaft rotation, no matter if its a 4 cylinder, 6 cylinder or a V10.