There have been opposed piston 2 strokes in use in old submarines and other applications. Usually with 2 crankshafts connected by shaft and bevel gear. They do not use the fuel as lube, as they are not crankcase induction as small 1 piston 2 strokes use. 2 stroke truck engines generally also use a vein type blower for induction.

There was also the deltic opposed piston 2 stroke engine. I think the English messed with it as a ship engine- lots of power in compact design, but finicky.

http://en.wikipedia.org/wiki/File:Na...tion_large.gif

 

the radial engine posted in the breakroom is an old design. I haven't seen the opposed piston design before, but that doesn't mean it hasn't been done before.

Then again, there are people making all kinds of engine claims right now. Watching the history channel last night and a french company is claiming 200 miles for $2 of electricity by using their compressed air engine running at 4000 PSI.

 

Older than that, even! The Oechelhauser & Junkers 2-stroke made in 1893 to run on blast furnace gas. Opposing pistons run off one crank. On the way up to the outer piston the rods ran the scavenging and fuel gas pumps.

 

The Napier Deltic has gotta be one of the coolest designs ever. I think the biggest problem with it is that you have 3 cranks and they all have to be big and heavy. It puts a lot of power in a small package, but I don't think the power/weight ratio is any better than a more conventional layout. And then you add the troubles of oil control in the inverted cylinders...

 

Beat me to it. My boss who worked in the Marine industy and navy told me about it a while back. Cool design. Seams like it would be a very smooth running engine.

http://www.fairbanksmorse.com/engine...rine_power.php

edit: notice they are celebrating the 70th anniversary of the design.
Silly DARPA.