Algodoo

WARNING:
This scene runs at 1200 Hz frequency. For some users this may lag horribly.

Top speed is 1,884 rad/s (17,990 RPM). It doesnt put out much torque but that can be fixed by increasing the spring constant (for your own use).
Feel free to copy it and use it in some of your creations.
Press the left arrow to get it started.
The down arrow is a brake (although it barely affects the engine at full speed).
The green circles deflect the moving engine to stop vibrations (trust me, it gets really bad because algodoo does not make EXACTLY perfect circles...)