In addition to gasoline, the engine runs on rubbing alcohol and acetylene.

It’s easy to take the internal combustion engine for granted since they are so prevalent. Without the ingenious design, the vast majority of vehicles on the road wouldn’t go anywhere, though. Now, a fascinating new video offers a glimpse inside one at work.

The host from the Warped Perception channel fits a transparent top to a Briggs and Stratton single-cylinder flathead engine. The old-school design puts the valves beside the cylinder; hence sidevalve is another name for this layout. The structure means that from the top of the powerplant you can see the strokes of the cylinder and watch the valves in operation. While simple by modern standards, flatheads were the backbone of early motoring because they were easier to build and could better cope with the poor quality fuel of the time.

Even if you know how an engine functions, seeing it in slow-motion and in 4K is amazing. You can see the spark plug work and then the explosion as the fuel ignites. The exhaust valve opens to suck away the gases, and then the process begins again. It’s quite mesmerizing.

Transparent engine

After showing off how traditional gasoline combusts in the engine, The host of Warped Perception moves to different forms of fuel. The host then switches to rubbing alcohol, and it makes a huge difference. The spark plug can’t fully ignite the mixture, and the cylinder begins to fill with liquid. There’s still just enough combustion for the piston to keep moving, though.

Finally, the host tries two methods of fueling the powerplant with acetylene gas. First, it goes into the cylinder with a small mixture of alcohol, and the engine seems to run well. There’s far more black smoke than the other power sources, though. Warped Perception then switches purely to acetylene, and the results are initially rather explosive.

Gallery: Transparent running engine video