Question

In which step of the four stroke engine cycle does the heat from the combustions reaction cause the pistons to move?

Answer 1

You would probably get a better explanation in the physics part of open study. This happens in the third step of the cycle, or third stroke, which is the combustion stage. This is where the crankshaft has completed a full revolution. While the piston is at the end of the compression stage, the pressurized air and fuel is ignited by a spark plug, and this combustion forces the piston back down.

Answer 2

3 = Combustion: This is the start of the second revolution of the four stroke cycle. At this point the crankshaft has completed a full 360 degree revolution. While the piston is at T.D.C. (the end of the compression stroke) the compressed air-fuel mixture is ignited by a spark plug (in a gasoline engine) or by heat generated by high compression (diesel engines), forcefully returning the piston to B.D.C. This stroke produces mechanical work from the engine to turn the crankshaft.


https://en.wikipedia.org/wiki/Four-stroke_engine