Connecticut-based startup LiquidPiston announced today that it has built a compact engine powerful enough to drive a go-kart. The firm’s X Mini engine weighs just four pounds and has just three moving parts, yet it can produce 3 horsepower, enough to serve as a replacement for a roughly 40-pound piston engine that normally powers the subject go-kart.

LiquidPiston says that its X Mini remains in a testing phase, and the company hopes to get the weight down to three pounds and the output up to 5 horsepower. (The 40-pound piston engine produces about 6.5 horsepower.) In the meantime, the little engine already packs a punch, as you can see in the video below.

LiquidPiston announced last year that it had received a $1 million DARPA grant to develop the X Mini engine, and now we see where the money went. The engine is small enough to fit in the palm of your hand, yet it can power everything from vehicles to generators to drones. The X Mini uses LiquidPiston’s proprietary rotary engine design, which is said to offer thermodynamic improvements over both a traditional Wankel rotary engine and common piston engines. LiquidPiston says the X Mini can run on Jet Propellant 8, the military’s fuel of choice, making it an ideal candidate for all sorts of military applications. For instance, the X Mini is small and light enough to power a UAV, it can be part of a generator that can be carried in a backpack, or it can even be used to power military robotics. Ac...