The Oscillating Piston Engine (OPE) is a revolutionary (pun intentional) engine design that the patent holder Rotoblock promises will reduce weight and complexity, as well as offer an improved power to weight ratio over a standard internal combustion engine.. We could explain at length how the OPE works, but we'd spend the next three days moderating comments about all the things we got wrong. So, watch the flash animation above from Rotoblock's Web site and check out an in-depth explanation of the engine at Green Car Congress. There's also a video of the engine running here. It sounds oddly like an aviation powerplant.

While it's a novel engine design, the OPE is not all that new. Designs for toroidal internal combustion engines have been around since at least 1968, and the patent now owned by Rotoblock was filed in 1993. What exactly Rotoblock plans to do with its patented engine isn't clear. The Web site says it can be used for almost everything from RC cars to generators to family sedans. The company's site also claims the engine can be adapted to run alternative fuels, including hydrogen. Rotoblock has even announced a partnership with Apollo Energy Systems to develop a hybrid drive train using the OPE.