There’s been a few clips surface on the internet over the years showing the inner workings of an internal combustion engine. However this 4K video recently uploaded by Matt Mikka of Warped Perception is easily the best one I’ve seen.



In the video, a 3 HP flathead Briggs and Stratton 4 Stroke Internal Combustion engine is converted with a see-through cylinder head, allowing us to see exactly what’s going on with each stroke of the engine, in Ultra Slow Motion.

The engine is taken from a rich state to a learn state, also also run through various fuel types including gasoline, Isopropyl Alcohol and Acetylene for comparison.

The four strokes of the engine are clearly visible:

1. The intake valve opens to let the air and fuel mixture in to the combustion chamber as the piston moves down.

2. As the piston moves up, the intake valve closes, and the air/fuel mixture is compressed.

3. The air/fuel mixture is ignited at the optimum moment immediately after the piston reaches top dead centre of it’s stroke.

4. The exhaust valve opens as the piston moves upward, forcing out the exhaust gasses and any remaining unburnt mixture.

The video also clearly demonstrates the importance of both air/fuel ratio, as well as correct ignition timing in order to produce a clean and complete burn. Optimum ignition timing is crucial to engine performance and reliability. Too soon and not only do you loose power, but massive amounts of stress are put on the piston and connecting rod. Too late and the amount of useful work exerted on the piston is greatly deminished, greatly reducing the engine’s power output.