How It Works

LiquidPiston’s X Engine is a non-Wankel rotary embodiment of the company’s innovative High Efficiency Hybrid Cycle (HEHC). The X Engine has few parts and three combustion events per rotor revolution, resulting in tremendous power density.


This video shows an X engine operating on compression-ignition HEHC. The spark-ignition HEHC, X Mini, has a similar architecture but operates at a lower compression ratio.

The X Engine’s few moving parts consist of a rotor (the primary work-producing component) and an eccentric shaft. Except for ancillary parts such as injectors, fuel pumps, and oil pumps, there are no other moving parts, making the X Engine extremely simple and elegant.

LiquidPiston’s X Engine architecture geometry allows for standard materials and 2-D manufacturing to be used, greatly decreasing the design, build and testing cycle.

While it is a rotary engine, LiquidPiston’s X Engine is NOT a Wankel engine. It has a fundamentally different thermodynamic cycle, architecture and operation.