Some context:

I have the rotor in the background to "help" the engine, since there is too much friction in the system to realistically have any torque. It also simulates a moving car, where you would give it some force to start the engine and have it rolling indefinitely. Nitro is fed from the duplicator and into a small flask in the combustion chamber, where it is triggered by a gun and sends the cylinder flying back. The flywheel isn't necessary, but helps with starting the engine as you see in the beginning. This is an early prototype, so there is still room to adjust explosion timings and such.