Listen to the World’s Smallest Rotary Engine Scream at 30,000 RPM

The microscopic motor has just 2.46 cubic centimeters of displacement.

byPeter HolderithJun 21, 2022 4:50 PM
The world's smallest rotary engine.
Warped Perception via YouTube
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Rotary engines are already known for their high RPM; the smaller they get, the higher they tend to rev. So what happens when the world's smallest rotary engine gets put to the test? Well, 30,000 RPM is what happens.

The engine, known as the RS-S100 and built by miniature engine manufacturer Toyan, was recently tested by the Warped Perception YouTube channel. The channel is known for all kinds of automotive-related shenanigans, including other miniature engine tests, but its host, Matt, has never pushed any small motor to 30,000 RPM. It's an impressive feat, especially considering the RS-S100 costs right around $500.

The microscopic rotary is just 2.46 cubic centimeters or 0.15 cubic inches. According to Stirlingkit.com, a retailer of such small engines, it's rated to a maximum redline of just 16,500rpm and makes three-quarters of a horsepower at 14,800rpm. It has no lubrication system and must be run on a mixture of fuel and lubricating oil, similar to a two-stroke piston engine.

Matt clearly didn't get the memo on the engine's rev limit, or, to be fair, the engine itself didn't. Using a digital tachometer to read a piece of reflective tape on the flywheel, the engine spins up to 30,000 RPM. Some ear protection is definitely called for if you decide to buy this thing.

The motor vibrates so violently that it eventually shakes its tiny exhaust pipe off. It also melts the glow plug meant to help ignite the air, fuel, and oil. That being said, Matt stops just short of causing permanent damage to the engine as he plans to use it in another project. Before that happens, though, modifications will be necessary to the apex seals—those seem to be about the size of a grain of rice—in order to boost the compression to a more acceptable level and get better idle performance.

Despite the exciting, high-revving, energy-dense nature of rotaries, no vehicles today are equipped with them. The last rotary-powered vehicle, the Mazda RX-8, went out of production in 2012. In fact, the very last rotary engine to be fitted to an RX-8, a 1.3-liter "Renesis" two-rotor, was built on this day, one decade ago. Unless Mazda decides to finally bring the rotary range extender to its MX-30 electric vehicle, the unique motor will remain a toy for enthusiasts and hobbyists, as it's seen in the video here.

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