An ingenious idea from Bruce Crower, dubbed the Crower six stroke, which adds a fifth and sixth stroke to the traditional four stroke process in an internal combustion engine. The fifth stroke is an additional power stroke without fuel, which is done by adding a small amount of water into the chamber, which is immediately converted to steam due to the heat in the chamber from the just-completed explosion. The sixth stroke then exhausts the steam into a reservoir, where it can be reused. The extra strokes essentially eliminate the need for external engine cooling (ie., a radiator) — the engine runs just warm to the touch.

There are still a myriad of problems to be overcome, and I won’t be seeing this in my Jeep any time soon, but this is a very interesting idea.