Video: The Secrets Of The Rotary Engine, Seen From The Inside

If you’re not familiar with the Wankel rotary engine, pull yourself up a chair, crank into a cold brewski, and fire up your headphones, because you’re about to see just how one of these diminutive, wonderful engines turns burnt gasoline into horsepower. With a long and illustrious history of usage in many Mazda RX-series sportscars, planes, helicopters, motorcycles, and more, the rotary engine is lightweight, with high power output by displacement. There are other rotary engine designs, such as the Baylin engine and the LiquidPiston engine, but the Wankel is the most well-known of this style of internal combustion engines. Warped Perception takes us through the details.

Constructed with few moving parts, the Wankel rotary is a model of austerity with respect to its design; the triangle-shaped rotor (piston) and the eccentric shaft, which serves the same purpose as a traditional crankshaft. The video details the engine’s operating cycles, which consist of—surprise, surprise—suck, squeeze, bang, blow.. although not in the traditional format you’d see in a four-cycle internal combustion engine.

In fact, in the Wankel, the squeeze and bang cycles are combined into one portion of the rotary cycle; after the rotor passes the fuel source (in this instance a carburetor) and as it moves around the kidney-shaped housing to the combustion chamber, the mixture gets compressed and ignited at virtually the same time.

At the top right is the combustion cycle, captured in 4K. It took 226 video takes—and an injection of acetylene—to get the combustion process to show up in living color as you see here.

This guy takes it one step further, though. Not only does he give a quick rundown of rotary engine operation, he then sets out to build the see-through engine to show all of us how the rotary operates. And this is where the video elevates itself from pedestrian “this is how a widget works” to “check out these contained explosions and understand just how this engine works, from start to finish.”

Through the magic of filmmaking, we can see the mixture enter the engine, combust, and then fling the rotor around the housing to evacuate the exhaust as it continues through the power cycle.

Also as an aside, we can see the harsh life that the apex seals (the flat blades on each rotor tip) have to deal with; from the eccentric shape of the housing to the immense temperatures and pressures that are seen on the power stroke, it’s kind of amazing that this engine design ever succeeded at all. But as we know Mazda is still working on the Wankel configuration, there’s hope for it yet.

Easily the coolest video you’ll see all week!

About the author

Jason Reiss

Jason draws on over 15 years of experience in the automotive publishing industry, and collaborates with many of the industry's movers and shakers to create compelling technical articles and high-quality race coverage.
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