As you may have heard, YouTuber Rob Dahm is building an outrageous third-generation (FD) Mazda RX-7 featuring a four-rotor Wankel engine. It’s an engine layout that has never been used in a production car before?every factory rotary vehicle has come with only two, at most three, rotors in its spinny-triangle engine. And, as you can imagine, building a four-rotor is way more complicated than just joining two twin-rotor motors at the eccentric shaft.
Jason Fenske of Engineering Explained is here to elucidate just what it takes to build a four-rotor engine that won’t tear itself apart the first time it’s fired up. Just as in a piston engine, the firing order has to be precisely engineered. Imbalanced combustion events will create terminal stresses, bad news for any engine, but especially bad in a high-horsepower build. Dahm is aiming for a 10,000-rpm redline in this monster rotary, so everything has to be done to exacting precision.
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The answer" A unique firing order unlike anything you’ve seen in the familiar two-rotor Wankels that prowl the streets of the world. Here’s Engineering Explained to show you the how, and the why, of this unique engine.

This story originally appeared on Road & Track.

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