Unfortunately, it is difficult to find details on the Stelzer engine, because Frank Stelzer is a German in Germany. And it seems that there are certain forces at work to curb the promotion of the engine.

The Stelzer engine was displayed on the cover of the old "Science and Mechanics" magazine, in an issue way back in 1980 or 1981, or possibly before. At the time, it was said to have 25% better fuel economy. And it is obvious that it has far few moving parts, and a form that makes it reasonably easy for any home metal-working machine shop to build one.

Here is a link to a video of Frank, himself, running a test model of the engine: http://www.youtube.com/watch?v=YR5PGGKS4ys

I won't take the time here to explain all the hidden advantages to this engine - advantages that might make this engine the most fuel-efficient gasoline engine in the world if it were fully developed - but suffice it to say that the Stelzer engine could be made to run on the ping, the detonation, that your regular car engine tries to avoid. Why does your car engine try to avoid detonation? Because it is so powerful that it can destroy an engine.

In other words, the most powerful part of the operation of a car engine is exactly the thing that the engine is made to avoid - because the modern car engine is a stupid piece of inefficient junk.