At bottom-dead-center (BDC) the inlet valve is closed and the compression stroke (b) starts. Work is done on the air/fuel mixture ... represents this behavior for a Mitsubishi direct injection engine ...

Basically, this thing is a mashup of four-stroke and a two-stroke engine designs (here's how an engine works, by the way), ...

Along with a TIG welder and mechanical ingenuity bordering on genius-level, all of which come to bear on this fridge compressor to four-stroke engine build. The video posted by [Let’s Learn ...