Algodoo

An engine which used rapidly expanding particles(AKA explosion) to run. Almost works like an real engine, but it make no fumes.
The engine will stall if there's too much particles, so a limiter(AKA gear) is installed. Crank the engine with the drag tool and copy&paste the particles into the particle tube or whatever. Also, it's extermely unstable and may stall if it runs too fast.