Liquid Piston has taken its revolutionary engine out for a spin. The Connecticut-based startup has been developing a tiny new type of rotary engine for several years that’s so innovative it received a $1 million contract from DARPA. Previously shown only in lab tests, it has now been installed on a go-kart to demonstrate its abilities in the real world.
The X Mini weighs just four pounds without its fueling system installed, and is about the size of a small melon. It currently produces 3.5 horsepower, but the company says a future iteration will shrink to three pounds and put out five horsepower, which is similar to the output of a much larger, heavier 50cc piston engine.
But what makes the X Mini unique is its design, which is essentially a Wankel rotary turned inside out. Instead of a triangular rotor in a peanut-shaped housing, it has a peanut-shaped rotor inside of a roughly triangular housing with rounded combustion chambers and spark plugs located at each apex.
According to Liquid Piston, this arrangement addresses many of the shortcomings of the Wankel. In particular, it uses fixed seals that eliminate the need to blend lubricating oil into its fuel mixture, which improves its emission performance, while cavities built into the rotor allow for overexpansion of the combusted fuel that increases the engine’s efficiency. That fuel can either be gasoline, diesel, natural gas or military grade JP-8.
Although Liquid Piston says the design can be scaled up to a 1,000 hp version, the company is currently targeting a developing market for small, quiet engines that can be used to power drones, robots, backpack generators, handheld power equipment and motorcycles.
The X Mini isn’t yet commercial available, but Liquid Piston is now offering a complete development kit for $30,000.