Last time we checked in on the X Mini engine developed by LiquidPiston, it was hailed as a power-dense prototype with only two moving parts and weighing only four pounds. Despite its iPhone size, it was touted as being capable of 3.5 to 5 horsepower while spinning up to 15,000 rpm.

Now the company has released a proof-of-concept demonstration video showing it powering a go-kart. Officials took out a standard basic go-kart engine that weighed 39 pounds and was rated at 6.5 horsepower, then dropped in the X Mini. Built with a 70 cc displacement, the X Mini was rated at three horsepower. From the video it looked like the LiquidPiston team had to add another set of gears to accommodate the higher revs. The video also shows how simple the engine goes together.

The X Mini engine weighs about four pounds and is little bigger than an iPhone.

Lasting less than a minute, the video closes with a quick test run of the go-kart.

No A-B testing was conducted. No numbers to compare were released. Officials simply said interested parties can place orders for the X Mini development kit, which includes a prototype engine, for $30,000. Additional equipment will also be available, including ECU for $2,000; mobile dyno for $25,000 and engineering support for up to $175 per hour plus expenses.

As noted in EL’s previous story, the X Mini is based on LiquidPiston’s patented thermodynamic cycle and engine architecture. It looks somewhat like a Wankel rotary, but the combustion process and airflow is quite different. Basically there are three combustion chambers and three power strokes per revolution.

Here’s how the X Mini compares to the Wankel. The X Mini has three combustion chambers and three power strokes per cycle, where the Wankel has just one. You can see that the Wankel has a triangular rotor in a peanut-shaped housing. The X Mini is reversed: there’s a peanut-shaped rotor in a triangular housing. The X Mini also has a higher compression ratio.

Called the High Efficiency Hybrid Cycle, the engine is said to optimize fuel efficiency by combining the best features of four automotive engine cycles, including the high compression ratio of a diesel, the constant volume combustion of an Otto cycle, over-expansion to atmospheric pressure that is featured in the Atkinson and the internal cooling with air or water such as found in the Rankine. To learn more, check out the video below.

Possible applications for the X Mini include handheld power equipment, lawn mowers, generators, small scooters or mopeds, unmanned drones, robotics, range extenders and auxiliary power units. LiquidPiston is already in partnership with DARPA to explore military options.