This is the LiquidPiston X2 diesel rotary engine. It’s a compact unit that produces about 40 hp. The amazing thing about the X2 is that it achieves a thermal efficiency in the neighborhood of 75% which is unheard of for internal combustion engines. It achieves this with a constant volume slow burn of the air/fuel mixture. Head over to Gizmag to read more of the details on the X2. They were able to interview the President and CEO of LiquidPiston.