This Super Small, Rotary Combustion Engine Could Power Your Next Motorcycle

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It's not a rotary, per se, but the internals do rotate.

The engine. It's a testament to its initial design, as whether it's in a V-configuration, W, H, or even flat, it really hasn't changed its operation since its invention.

That is, of course, except for the rotary engine.

Developed by a Nazi, but actually designed to work by a Pole, the rotary wasn't the advancement that everyone hoped it'd be. It was supposed to be small, light, and rev-happy. Which is technically was. But it was also notoriously difficult to tune correctly, a massive pain to service, and ate both fuel and oil like it had just survived a deserted island and found itself at an all-you-could-eat buffet. In fact, it was such a pain, nearly everyone abandoned it apart from a few weirdo one-offs here and there.

I'm looking at you, Mazda and Suzuki.

But what if you took the two engine designs, i.e. a piston-driven engine and a rotary-driven engine, and combined them? Would it be the best of both worlds? Or would it be an unmitigated disaster?

Well, one researcher was determined to find out and developed this: the Avadi engine.

The Avadi engine works a lot like a normal piston-driven engine, as a piston is driven up and down a cylinder which creates combustion. But unlike other piston-driven motors, instead of connecting to a central crankshaft that then sends power to a transmission, the Avadi engine is connected to a central planetary gear, rotating a shaft (like a rotary) that then sends power outward.

The result is an incredibly compact four-stroke engine with solid power density.

How dense you ask? The working prototype is a 250cc single-cylinder engine, and produces about 15.8 horsepower and 22.3 lb-ft of torque at 3,500 rpm. But the whole unit weighs just 23 pounds. That's pretty wild figures given, as New Atlas reports, Honda's GX240 spits out "8 hp (6 kW) at 3,600 rpm and 12 lb-ft (17 nm) of torque at 2,500 rpm, weighing in at a hefty 77.2 lb (35 kg)."

New Atlas reports that there's been a lot of backend turmoil within the company since it first showed off its design back in 2022, including the CTO being forced out of the company. But Avadi's CEO Landon Wilkinson told the outlet that after a redesign to solve for inefficiencies, "The revised engine design is coming along nicely. We achieved positive compression results last week with the new valve design and anticipate run tests in the near future."

That statement was as of last month, so maybe there'll be something cool on the horizon to get us excited about.

But like I said, engine tech has relatively stayed stagnant for over a hundred years. And with more and more countries outlawing combustion motors due to their emissions and inefficiencies, new technology like Avadi's could be its savior, as e-fuels are coming into play, and EVs fall out of favor with the general public.

Well, the Avadi could be that, so long as it works.

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