[mikepurvis]

I saw an article about that idea a few years ago, and wondered if it might be possible to combine it with a rotary engine. I ended up creating this rather odd-looking model:

http://sandbox.mikepurvis.com/design/engine.svg

Completely impractical, but an interesting experiment. There's some more general info on Wikipedia: http://en.wikipedia.org/wiki/Six-stroke_engine