A GO-KART ISN’T the most obvious place to find the engine that could change how cars, drones, and anything else with a motor gets around, but it makes sense when you think about it. Karts are small, cheap, and crazy fun. “It’s a thrilling ride,” says Alexander Shkolnik. Shkolnik is the president and co-founder of LiquidPiston, a Connecticut firm that has spent 13 years and $18 million rethinking the rotary engine that Felix Wankel created in 1960 and Mazda gave up on in 2012. On Monday, engineers yanked the 39-pound conventional engine out of a kart and installed the four-pound X Mini. Although it took a moment to really get going—you’ve really got to get the revs up before anything happens—it performed exactly as planned. “It’s really great to see,” Shkolnik says. A Wankel engine replaces reciprocating pistons with one or more triangular rotors that follow an elliptical orbit within a peanut-shaped chamber. Combustion occurs in the spaces between the triangular and circular shapes. The design, used most successfully by Mazda, allows for an engine that can run at higher speeds and produce more power than a similarly sized conventional engine. It’s also light and compact.