What you get when you invert a Wankel engine

Though it looks like a Wankel, it is actually an HEHC (high efficiency hybrid cycle) engine that combines a high compression ratio, constant-volume combustion, and over expansion. It has a theoretical efficiency of up to 75% and comes from LiquidPiston Inc. in Bloomfield, Conn. LiquidPiston considers it an inverted Wankel, retaining the high power density and smooth operation of the Wankel while overcoming the lubrication and emissions challenges as well as problems stemming from the shape of the combustion chamber. For one thing, the seals are in the housing, not in the rotor. The gasoline version visible here would develop 3 to 5 hp, and the company also had a slightly larger see-through diesel example at the booth that would be able to develop 20 to 40 hp. Company officials say the planned use would be as a fuel-efficient range extender for EVs though they have also fielded a demonstrator in a go-kart.
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