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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?

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for a 4 stroke engine you get on average half a power stroke per cilinder per rotation. – ratchet freak Feb 29 at 16:00
    
You resurrecting an old DKW? :-) – Carl Witthoft Mar 1 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.

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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. – Carl Witthoft Mar 1 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.

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