You may have read about the opposed piston opposed cylinder engines in the news, after bill gates has agreed to fund research - I found a technical video, which I found very interesting.

http://www.engineeringtv.com/video/Opposed-Piston-Opposed-Cylinder

Not exactly a new concept, google Napier Deltic

Davie

oh right, still interesting

Also used in the Commer TS3 lorry along with a supercharger IIRC

This is not new I worked on a version of this 32 years ago when I was an apprentice at the British Inernal Combustion engine resurch institute, notice the ports it cannot run without forced induction.

I think whats interesting about this engine is that it's a four piston , twin opposed cylinder engine - with a single crank .
AFAIK all the other opposed piston engines had multiple cranks ?

The engines we were working on had single crank's, but had a beam and a pivot .

I've often thought a twin piston design is the way forward, never clicked the idea of having the pistons sharing a crank. Rather neat idea.