# How many power strokes per rotation in a 3 cylinder engine?

How many power strokes occur for every complete rotation in a regular 3-cylinder engine? Or in other words, every how many degrees does a new power stroke takes place? Does anyone know please?

• for a 4 stroke engine you get on average half a power stroke per cilinder per rotation. Feb 29, 2016 at 16:00
• You resurrecting an old DKW? :-) Mar 1, 2016 at 15:49

Each cylinder produces a power stroke for every (2-stroke engine) or every other (4-stroke engine) rotation of the crankshaft.

A 3-cylinder, 4-stroke engine will produce 3 power strokes for every 2 rotations (720°), or one for every 720°/3 = 240° of rotation.

• Mr. Nitpicker warns that a real-world 3-cylinder engine may well be designed so that the actual power-stroke spacings are asymmetric so as to reduce resonances. Mar 1, 2016 at 15:50

A stroke consists of either one expansion, or one contraction. As such it corresponds to half of a rotation of the shaft.

In a three cylinder engine, each cylinder will stroke with 2 strokes per revolution, so that's 6 strokes per revolution.

However, in a four stroke engine, it takes four strokes for each cylinder to complete one cycle, and only one of those strokes is the power stroke. Thus, there are 1.5 power strokes per revolution, or a power stroke every 240 degrees.

According to the answers, in 3 cylinder , 4 stroke we have power each 240°, as we have 1500 rev. Of 720°, it means we will have this: 1500 x 1.5 = 2250 power stroke at 3000 rpm, is it right?