DARPA has awarded LiquidPiston Inc. $2.5 million to continue development of a new, patented, high-efficiency, lighter-weight rotary engine. LiquidPiston, a developer of advanced combustion engine technology, received the award for the first phase of a program to realize the full capability of its patented high-efficiency hybrid cycle (HEHC) engine. This is the second award DARPA has made to LiquidPiston in the past 18 months, following an earlier test program for a different LiquidPiston rotary engine prototype, which achieved promising results.

LiquidPiston will be developing its X4 test rig: a prototype 30 kW diesel X-engine, with targeted brake specific fuel consumption (BSFC) of 186 g/kWh (better fuel efficiency than heavy duty truck engines, and twice the fuel economy of a gasoline engine over a typical drive cycle). The X4 is designed for extremely high specific power, with an objective of 1.5 hp/lb, making it up to ten times (10x) more powerful than a standard diesel engine with the same weight.