What Is a Rotary Engine

There have been V-16s, twin-supercharged H-12s, W-8s, Inline-6s, strung-out manic turbo-4s, and everything in between for the internal combustion engine. … Continued

There have been V-16s, twin-supercharged H-12s, W-8s, Inline-6s, strung-out manic turbo-4s, and everything in between for the internal combustion engine. But one of the wildest powertrain designs in automotive history forsakes the piston-driven combustion used in those engines for a design that looks like it uses a Dorito. We’re talking about the rotary engine. 

Enthusiasts will already be aware of the rotary and its ear-piercing scream, but even the well-informed might not know its history, its inception, or if it’s still in production today. Thankfully, you have Car Bibles to show you the way. Let’s dig in. 

What Is a Rotary Engine?

The rotary engine is a type of internal combustion engine that, instead of using pistons, uses a single or linearly connected set of cylindrical housings and an inner three-sided rotor to produce combustion. 

How Does a Rotary Engine Work?

Like a normal V-shaped or an inline internal combustion engine, the rotary’s housing, or block, stays stationary while the rotor internally spins. Fuel and air are forced into the cylinder’s combustion chamber as the rotor spins. Spark from spark plugs ignite the fuel/air mixture and produces combustion. 

What’s the Difference Between a Rotary and V-shaped Engine?

The main difference between the two is the engine’s design. Whereas a rotary uses a three-sided rotor to create combustion, a conventional V-shaped or inline engine uses pistons. This difference slightly changes the shape of an engine, as well. That’s pretty much it.

What Are Apex Seals?

To ensure the combustion chamber stays sealed, a seal is attached to the apex, or tip, of the rotor. This is what comes into contact with the inner combustion chamber wall and is why they’re called apex seals. 

Is the Rotary Still in Production?

It isn’t. The rotary engine has an odd and tumultuous production history, with a handful of auto manufacturers halting rotary programs after only a year or so. The first of which was NSU, which is where the “modern” rotary engine’s design came to life. 

Birthed by literal Nazi Felix Wankel, the rotary was actually designed in pre-WWII Germany in the early 1920s. After the war, small German automaker NSUhired Wankel to build them a rotary engine. Wankel’s co-engineer, Hanns Dieter Paschke, took Wankel’s design and actually made it work. Once that occurred, NSU built a few prototypes, and a very small production of rotary engine cars were produced. 

NSU later sold off the technology to automakers such as Rolls-Royce, Suzuki, Mercedes-Benz, and also Mazda, the company that helped the rotary find its footing and brought it to mass production. The company recently announced that the rotary would return as a range-extender in the company’s new hybrid powertrain. 

Mazda’s Rotary Legacy

Mazda’s rotary legacy is one of sensation. Not only do you have a series of successful rotary sports cars for the public, i.e. the RX series and the beloved FD RX-7, but a truck, a couple of passenger cars, and, not to be outdone, a series of racecars that are some of the wildest in the business. One of which, the 787B, won Le Mans with a four-rotor engine and screaming 11,000rpm redline

Mazda ended its rotary fascination with the RX-8 in 2012 but kept it alive until 2017 with a single-seat race series.

The Car Bibles’ Rotary Engine Glossary

Welcome to Bible school!

Felix Wankel 

Felix Wankel is considered the founding father of the rotary, and indeed, he was the one who first birthed the design. He was also, again, a raging Nazi who somehow escaped hard prosecution because he was kicked out of the Nazi party twice. 

Hanns Dieter Paschke

The man who ACTUALLY invented the modern rotary engine design. 

NSU 

A German car company that brought the first rotary engine cars to life. It was later acquired by Audi and Volkswagen. 

The Car Bibles Rotary Engine Questionnaire

Car Bibles answers all your burning questions!

Q: Does Mazda Still Make the Rotary?

A: No, Mazda stopped building rotaries in 2012, along with the RX-8’s ending production. It continued using rotary engines in its single-make Star Mazda Championship until 2017. It’s since been confirmed that Mazda is looking to revive the rotary engine as a range extender, as mentioned above. 

Q: Why Is the Rotary Bad?

A: The rotary isn’t bad, per se. It’s just inefficient, as it eats gasoline and oil like they were infinite resources, and you were made of cold-hard cash. They are great at making noise and power, though.

Q: How Long Do Rotary Engines Last?

A: Most rotary techs will tell you that an engine needs a full rebuild between 80,000-100,000 miles. 

The Rotary Video Tutorial

Car Bibles’ editors understand that not everyone is a text-based learner. For those kinesthetic people out there, we have your back with a video showing you exactly how rotary works. We pulled it from one of our favorite, and most trusted, sources and it’s a great additional resource.

Car Bibles’ Favorite Rotary-Related Products

You can buy tools for rotary maintenance at almost every auto parts and home improvement store. As well as online stores like Amazon. You have a sea of options to select from. But why even mess with all that when you can just listen to us! Like this extended warranty from Mazda, or octane booster!

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Jonathon Klein

Jonathon KleinJonathon has jumped Aston Martins for Automobile Magazine, clocked 200 mph in a McLaren 720S for Playboy, and sampled his best life behind the wheel of a Ferrari Dino Evo for Road & Track. He’s hopelessly addicted to the strongest coffee he can brew. Please send him more. Contact the author here.