Our favorite engine at the 2009 SAE World Congress was this awesome piece of engineering from Vengeance Power. It borrows concepts from several different kinds of engines and improves on them in certain aspects. Think of it like a sliding vane superchager improved in every possible way and made to burn fuel. The engine was designed to alleviate one of the worst flaws of the Wankel rotary design, the rapid expansion of combustion chamber volume after ignition, reducing the amount of physical work that can be done with each stroke.
The Vengeance engine uses an almost oval-shaped engine block liner designed to let the gasses expand more slowly, so they can do more work than a Wankel. The combustion chambers are formed by eight sliding vanes, riding on two sets of offset roller bearings and guided by a tracking cam to follow the oval block shape. The vanes are also sealed on three sides by some specially designed contact seals. In all there are only nine moving parts but the model shown is capable of 550 HP and 2500 lb-ft of torque at 1200 RPM.
The engine is targeted primarily as power sources for generators and according to Vengeance they'll be quite well suited to the task. Roller bearings and no reciprocal motion means low vibrations and the compact size means it'll fit into a lot of places. They're also claiming a 50% stoichiometric efficiency on natural gas, 53% with gasoline and 67% on diesel, which is outstanding. Furthermore it's claimed the cost to build is 80% of an equivalent piston engine. Sign us up.