Video: What Killed the Wankel Rotary Engine?

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Who or what killed the beloved Wankel rotary engine? Here’s the always helpful Jason Fenske of Engineering Explained to lay out the problems in bullet-point form.

 

Conceived by the mechanical engineer Felix Heinrich Wankel (1902-1988) of Germany, the Wankel rotary engine is arguably the auto industry’s most successful alternative engine design. Early Wankel-equipped production vehicles included the NSU Wankel-Spider and Ro-80, and in response to the engine’s exciting potential, licensing agreements were quickly snapped up by Curtiss-Wright, Daimler-Benz, General Motors, and others. But it was Mazda of Japan that put the rotary on the map, optimizing (if never totally perfecting) the engine for production use, most notably in its series of RX-7 sports cars. The rotary-powered Mazda touring and sports cars, while no longer in production, enjoy a loyal following to this day.

But despite the rotary’s successes in motorsports and elsewhere, there was always a visible ceiling on its potential for passenger car use. There are a number of ways to frame the rotary’s limitations, but in the video we feature here, automotive YouTuber Jason Fenske of Engineering Explained has distilled them to four:

+   Low thermal efficiency

+   Rotor sealing

+   High oil consumption

+   Poor emissions and fuel economy

That’s a lot of ground to cover, but here Mr. Fenske manages to lay down the important points in a little more than five minutes. With more than 7.4 million views over the past six years, the video is something of an internet classic. Enjoy.

 

15 thoughts on “Video: What Killed the Wankel Rotary Engine?”

  1. Unfortunately, the poor durability of the seals is incorrectly explained. they are not durable for the reason that EVERY revolution of the shaft, they have to “follow” to run on a DIFFERENT curve of the cylinder. hence it wears quite rapidly .. here is a drawing showing what is the difference between my engine’s sealing and Wankel showing the problem of exaggeration … for understanding https://new4stroke.com/wankiel.jpg

  2. While I was never a fan of the Wankel engine I have to admit that it had its place. Horsepower to weight ratio was a major factor. A friend of mine had an R100 with the Wankel. It ran just fine until that fateful morning, on the way to work, it just DIED, at the stoplight. That was the end of the engine. Of course the car itself was not far behind it. For spending its life out west in the Chinook Belt where there was very little salt on the roads, the body was dissolving. You had to watch where you put your feet or you’d be stopping like Fred Flintstone…

  3. There are a few companies buying up old Wankels and modifying them for aircraft use. Much of the engines are new including a better seal and better bearings to withstand prop vibration. Aircraft typically run at much higher rpms than cars. They got the idea from racecars using the engines.

  4. Mazda deserved all the more credit for getting a result so much better than NSU’s. The Ro 80 was sold only in the Bundesrepublik, where NSU technicians were on call 24-7 to come and change your engine on the side of the road.

    • Funny but not true!
      They were exported to a lot of countries. Also including USA.
      A design ikon, and their owners were looked up to for having the guts to be modern…

      • Have a look at the Wikipedia article. Yes, there were some Ro 80 exports–but with consistently horrible customer experiences.

  5. Everyone of these disadvantages that this “engineer “ pointed out was corrected years ago! I purchased a new RX8 in 2004 and drove it for 14 years without any of the problems that he pointed out. It got better mileage than the Explorer before it, By the timeIt was due for an oil change it was only a quart low. It passed emission test in every state. No, the rotary engine wasn’t killed because of its problems, but died because of unfair articles like this.

  6. The problem was they were not people proof. Due to high oil consumption they were run low on oil several times prior to failing. I worked for Mazda in the infant years of the rotary as a trained mechanic by Mazda. We had people come in with engine that failed. Oil in filter very dirty pull the dipstick ,,, clean oil. But they swore that they didn’t run it low on oil. 1 quart in 500 miles was not considered excessive. They had an oil pump that had two lines pushing oil into carb to keep it lubed and the oil came from the crankcase.

  7. I have a “working report” done by Chrysler regarding whether they were going to jump on the Wankel band wagon. The conclusion was they thought they were close to perfecting the turbine for consumer use so they would take a “wait and see” approach. If it appeared the Wankel was the “answer” they figured it would be cheaper to purchase from an outside supplier rather than tool up to build one themselves. .

  8. In to-days environment turbines attached to electrical generators could have much to commend it. Modern turbines are quite efficient and are extremely reliable.

  9. I had a 303 Wankel rotary in my 1972 Arctic Cat Panther snowmobile. Awesome power plant for its day.

  10. Knew a fellow in New Plymouth who went the other way – fitted a Subaru motor in an Ro 80; didn’t go as fast but was a solution to a problem and made a comfortable car reliable and vastly more fuel efficient.

  11. I once had a 1973 RX-2 bought used with a rebuilt engine certified by Mazda. Drove it for 70,000 miles. Then one day I saw white smoke coming out of the tailpipe. O-seal.

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