RX-Rated: Mazda’s Early Rotary Cars, Part 1

Model Histories, Sports Cars and Muscle Cars
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  1. Walter R. Moore

    I’ve always loved Mazda’s rotary cars. Fantastic article, and I can’t wait for part 2…

    Reply
  2. Bryce

    Great story looking forward to part 2. A friend in Tasmania had several of those bertone Luces nice cars the later models had the 1800 Capella engine.

    Reply
  3. Mike

    Thanks for the Mazda rotary article. I’m looking forward to reading Part 2. Despite growing up around Mazda rotary-powered cars, I learned quite a bit!

    Reply
  4. Johnny Reno

    It’s a real shame that no one can seem to lick the engine’s fuel and oil consumption problems. I have heard some discussion of Mazda using rotaries in hybrids, which makes some sense to me. Rotaries are so small and, on paper at least, elegantly designed.

    Man, that Luce coupe is a looker.

    Reply
    1. Ate Up With Motor

      I don’t know about hybrids, but Mazda has done quite a bit of development on a hydrogen-fueled rotary, which has been offered on a limited basis for fleet sales in some markets.

      If the next-generation 16X engine materializes, Mazda is hoping to reduce fuel consumption substantially, in part by adopting direct injection. Still, since piston engines keep improving in that regard, as well, I don’t know that the rotary will ever match the reciprocating engine in specific fuel consumption. Some things can be mitigated (like wall quench), but other factors, like the combustion chamber surface area to volume ratio, are sort of the nature of the beast.

      The Luce R130 is indeed a very nice-looking car. I’d never seen one before I started researching this story.

      Reply
  5. Nicolas Daum

    Very interesting article, well, as usual, Aaron!
    The topic was somewhat forgotten in France after Citroën heavily invested in the technology, eventually failed to make it work and had to drop the project in the early 70’s. They had been so serious about it that the models developed in the late 60’s, the GS and the XM, were designed for a rotary. They had to hastily develop a reciprocating engine for the GS and make it fit in the engine bay that was not large enough.
    The XM eventually was painfully fitted with a Peugeot engine.
    Anyway Citroën was never able to design a good engine. This huge investment and its failure played an important role in the demise of the company.

    Nick

    Reply
    1. ego228

      “They had been so serious about it that the models developed in the late 60’s, the GS and the XM, were designed for a rotary.”
      You mean the SM, don’t you?

      Reply
      1. Ate Up With Motor

        I believe Nicolas was probably referring to the CX, which replaced the Citroën DS in 1974. I’ve never heard anything about the SM being intended for rotary power — of course the production cars had the Maserati V6 — but I think the CX was. The XM was the CX’s eventual successor, introduced in the late eighties.

        Reply
  6. Nicolas Daum

    Right Aaron, my pen slipped, it was the CX.
    The XM was its successor.
    The SM, stangely enough, was fitted with the (in)famous Maserati V6 even though Citroën had such a faith in the future of the rotary as the ultimate replacement of the reciprocating.

    Nick

    Reply
    1. Ate Up With Motor

      Timing may have had something to do with it. Citroën didn’t build the first M35 single-rotor cars until the fall of 1969, and as I understand it, they were essentially evaluation models, not yet intended for large-scale production. The BiRotor wasn’t introduced until 1974, about four years after the SM debuted. Even if Citroën were keen to give the SM rotary power, it probably wouldn’t have been ready until a few years after launch, even in a best-case scenario.

      If things had worked out differently, I imagine Citroën might have added a rotary engine to the SM later, perhaps in a second-generation version for the mid-seventies. Of course, even if the Comotor engines had been more successful, the SM was not, and might have been dropped without ever getting a rotary engine.

      Reply
  7. Nicolas Daum

    For them the rotary was the future type of engine for all applications, just as well as they were persuaded they had a market for the SM.
    With NSU, Mazda and others working on it it’s understandable.
    Your article is very interesting by showing how Mazda made a success of it, or at least could partly make a living with it, well… that’s a success, isn’t it?
    Strangely enough it didn’t catch on as an aviation engine either.
    Nick

    Reply
  8. Nicolas Daum

    [quote=Administrator] Citroën didn’t build the first M35 single-rotor cars until the fall of 1969, and as I understand it, they were essentially evaluation models, not yet intended for large-scale production. The BiRotor wasn’t introduced until 1974, about four years after the SM debuted.[/quote]
    Starting in 69 a limited number M35, and in 73 GS Birotor, were sold to selected, faithful (and masochist) clients but the engine proved such a burden to maintain that Citroën offered to buy them back and scraped them. A few people only turned down the offer. The maintenance contracts were canceled for them. The few models still in existence are now very expensive collectors’ items, the day dream of all the GS enthusiasts.
    So there was actually a future for the rotary! ;-) As usual the car that nobody wanted became the car that nobody can afford.

    Nick

    Reply
    1. Ate Up With Motor

      The source I was looking at (John Hege’s The Wankel Rotary Engine: A History) suggests that Citroën had basically intended to buy back the early evaluation engines from the outset, which would make a lot of sense.

      I don’t know about France, but in the U.S., automakers are legally obligated to provide parts support for production models for a specific period of time, typically 15 years — obviously not an appealing prospect for cars or engines that don’t end up in mass production! For that and other reasons, some automakers have tended to offer such evaluation vehicles only as a closed-end lease or other type of loan-out, with no option to actually purchase and keep the vehicle at the end; I assume that not actually selling it avoids triggering certain legal requirements.

      Reply
  9. Nicolas Daum

    The Europeans have basically the same obligations as the Americans. As far as I understood, the deal was under specific conditions and since Citroën offered to buy them back it could cancel any support for those who rejecter the offer. It’s stupid it didn’t keep one example for history.

    Mazda is the only one who succeeded with a rotary over the years while all the others flopped.
    Well done!
    Nick

    Reply
  10. ELW

    This is an interesting article as usual, I’m waiting for the second part. While you’re at it, how about an article covering GM’s attempt to build a rotary engine?

    Reply
    1. Ate Up With Motor

      I thought about it, but in researching this article, I’m finding that detailed information about its development seems to be surprisingly scarce. While the development of the NSU, Mazda, and Curtiss-Wright engines is pretty well-documented, GM played it very close to the vest. To really do it justice would probably require talking to some of the engineers who worked on it, assuming that the people involved are still living, and willing (and able) to talk about the program.

      Reply
  11. Webby

    No need to mourn it’s passing. A technological dead end. I don’t miss the
    ffffttttt exhaust “note” of them at all.
    Used to be a few about Brisbane, Delighted to see and hear that rust and enlightenment of the owners has made them almost extinct.

    Good riddence. So it could rev to 5 digits.
    BFD.

    Reply
  12. Scotty G

    Wow, FANTASTIC article! Thanks for the great piece on Mazda, the detail and depths you go to are above and beyond. One of the best history-of-automaker stories that I’ve read. Thanks again!

    Reply
  13. Don Andreina

    Another great article Aaron. Really appreciating your narrative drive and level of scholarship. I’m starting to believe the R100/1200 body was designed by Bertone as well, but can’t verify. Do you know of any text that addresses the connections between the Italian design houses and the Japanese manufacturers in depth?

    Reply
    1. Ate Up With Motor

      I so far haven’t found anything to suggest one way or another whether the first-generation Familia was done by Bertone, although it’s certainly plausible given that Bertone did the first Luce and the Luce Rotary Coupé in that period. Even if Stilo Bertone didn’t do the Familia or the first Capella, those designs have a definite Italian flavor, much more so than subsequent products of Toyo Kogyo’s in-house design studio, which feel more typically mid-seventies Japanese.

      Reply
  14. Joshua Finley

    I really like that little sidebar referring how to calculate the Wankel’s full displacement. I know Japan has different regulations than the U.S. and that Mazda had no choice to only count one chamber for each rotor (Geometric Displacement) due to extra taxes being placed on “bigger” cars. Either way, I really hope Mazda brings their Wankel rotaries back to the streets, because that awesome RX-Vision concept needs to be on the roads

    Reply
  15. Lotus Rebel

    In retrospect could the prospects of the Rotary have been slightly improved to a certain extent had Mazda and not Citroen established the Comobil later Comotor joint-ventures with NSU, where the development of the Rotary follows a more developed Mazda like trajectory instead of the engine being prematurely released as was the case with NSU and Citroen?

    Would that have been enough had it been feasible to largely butterfly away the poor reputation and resolve the issues of the early Rotary engines or would more changes have been required? Taking into consideration of course the current disadvantages of the Rotary would still remain.

    Reply
    1. Ate Up With Motor

      This is one of those “could / would /should” questions. The “could” part is straightforward, at least technologically speaking; Mazda obviously managed to keep the rotary at least reasonably viable for many years, so there’s no technical reason the fruits of their efforts couldn’t have been shared across a broader consortium.

      The “would” and “should” parts are more complicated. NSU-Wankel patent licensing agreements generally included technology-sharing provisions because NSU did not have deep pockets and figured that pooling research data would be the best way to advance the art. (Part of the reason GM’s patent license was so expensive is that GM didn’t want to participate.) Toyo Kogyo participated in that and probably contributed quite a bit to it. However, the way that knowledge was applied ended up being dictated by other factors, including a maze of different licensing agreements (like the one with Curtiss-Wright that affected distribution in North America), the concessions NSU minority stockholders wrested during the Audi merger, and the fact that the Comobil/Comotor project contributed to Citroën’s financial over-extension and eventual bankruptcy.

      Would NSU stockholders have agreed to set up such a consortium or joint venture with Toyo Kogyo? Possibly, and in that area, the progress Mazda had made with the technology might have been attractive. Would Volkswagen have been amenable to it after the NSU-Audi merger? Harder to say; I don’t imagine that Volkswagen or Audi were terribly keen on Comotor given the NSU shareholder concessions, and Toyo Kogyo being involved in that venture rather than Citroën (or succeeding Citroën) would not have changed that part of the equation. The minority shareholder deal ended up signing away most of the opportunity to profit from the rotary, and Volkswagen still wouldn’t have been in a position to use the rotary in its own products. (I don’t think Toyo Kogyo would have been in a position (financial or political) to acquire NSU instead of Volkswagen.) The main point of change in that scenario is that Toyo Kogyo by then had sunk enough money into development that they were more reluctant to simply shelve it.

      Should they have? It depends on a lot of things. If Toyo Kogyo had stepped in AFTER Citroën had been forced to bow out, the venture would have had to rebrand and might still have had a shaky image. There were customers who would have been interesting (AMC, to name one), but Mazda rotary combustion engines of the early seventies were still not without flaw, and the issues might have caused their licensees to jump ship early. (Toyo Kogyo commitment to the rotary had a lot to do with pride and the sunk-cost fallacy, to be honest.) Also, the OPEC embargo would still have really pressed the rotary’s limitations in terms of fuel consumption, which would have still hurt the project’s commercial prospects.

      So, an interesting idea, but I tend to see it coming to a similar end.

      Reply
      1. Lotus Rebel

        Do not envision a joint-venture between NSU and Mazda in place of NSU and Citroen significantly changing things once Volkswagen acquires NSU and merges it with DKW/Auto Union to form Audi, what with the fuel crisis hurting the rotary engine’s projects in Europe. That said the NSU Ro80’s issues would have been largely butterflied away for one thing, though not sure if it would be enough for Volkswagen to actually consider a rotary model for say the 914 (as was experimented in real-life) if not a small mid-engined sportscar or some other vehicle (.

        For Citroen there is one less contributor to its financial over-extension and eventual bankruptcy, leaving only one or few more elements (e.g. Project F, possibly acquiring Maserati for V6, SM instead of DS Sport, etc) to be remedied on its end without being involved in the Comobil/Comotor project. What Citroen goes from hereon is another matter, in the absence of the French government forcing Peugeot to acquire Citroen perhaps Citroen ends up increasingly entangled with Fiat or collaborates with one and more carmakers on a few joint-ventures outside of Fiat (e.g. Alfa Romeo? Subaru? both? etc).

        Essentially the rotary engine in this scenario would be better regarded compared to real-life thanks to Mazda’s early tie up with NSU and a thorough development programme (instead of being prematurely released), yet ultimately undermined by the fuel crisis and only really considered worthwhile for sportscars.

        Reply
        1. Ate Up With Motor

          The issue pertaining to the NSU-Auto Union merger (which is explained in more detail in the Ro80 article) is that Volkswagen ended up signing away the lion’s share of Wankel-related profits and agreeing that if it used the rotary in its own products, it would have to pay license fees like any outside customer. In the short term, that was a big win for NSU minority shareholders, but it probably contributed a lot to the eventual stagnation of rotary development outside Toyo Kogyo/Mazda. On the other hand, NSU’s survival WITHOUT a merger would have been very tenuous because they had also overextended their resources with the Ro80 and what became the Volkswagen K70. Whether Toyo Kogyo would or could have afforded a merger with NSU that would have obviated the need for the Volkswagen deal I don’t know; it would have been a politically complex situation, to say the least.

          NSU was undoubtedly aware of everything Toyo Kogyo had been doing regarding rotary development, which to my understanding was a condition of the original license agreement. (I assume NSU would still have had to formally license technology subject to Toyo Kogyo patents, although I don’t think that would have been an insurmountable obstacle.) However, the problem they both faced is that each was exploring different solutions to the challenges involved (like the apex seal issue), and it wasn’t yet apparent what would work best. Toyo Kogyo didn’t attempt anything quite as daring as the NSU floating seal design (which was a brilliant idea undermined by inadequate development testing), but the differences between the earliest 12A twin-dizzy engines and the better-developed 13B found in the first-generation RX-7 are pretty substantial. It’s not that Toyo Kogyo was smarter or luckier than NSU in this regard; it’s that they kept working on it and refining their approach to factors like sealing and porting.

          However, the upshot I assume you’re getting at is that an alliance between NSU and Toyo Kogyo might have resulted in a more lasting commitment to developing the rotary engine as a commercial prospect, with a Comobil/Comotor-style entity offering engines to other companies that were interested in the technology, but either couldn’t afford or didn’t want to spend the money on developing their own. The actual reason that didn’t happen was probably mostly that Volkswagen had very limited financial incentive to bother and Citroën, as mentioned, ran out of money. If Volkswagen were not in the picture (or the settlement with the minority stockholders had turned out differently), NSU survived on its own, and Toyo Kogyo took Citroën’s place as development partner, it might be plausible.

          One other fly in the ointment with that scenario, though, is European hostility toward Japanese automakers. As much as the emergence of Japan as a major player on the automotive scene aroused horrendous racism and nationalistic furor in the U.S., that hasn’t significantly dissuaded Americans from buying Japanese cars, to the point that domestic automakers have more or less abandoned many segments of the market to the Japanese and Koreans. European markets have not been nearly so amenable, and even products Japanese automakers have designed specifically for Continental or British tastes have often been commercial duds. Applying that chauvinism to the early seventies, it’s also not hard to envision a scenario where Toyo Kogyo partnership in a Comotor-type JV ends up leading European punters and pundits deciding that rotary engines are too Japanese, which combined with the pressures of the OPEC embargo might also have been a death knell.

          Reply
          1. Lotus Rebel

            Volkswagen could have attempted to use the rotary in more niche segments like Mazda did with front-engined sportscars though mid-engined in Volkswagen’s case, otherwise Volkswagen could be a passive beneficiary at best upon buying NSU.

          2. Ate Up With Motor

            As it says in the Ro80 article, there was a lot of enthusiasm within Audi-NSU for the planned Ro80 successor, including some fairly serious talk of installing its 1.5-liter KKM 871/EA871 engine in the Audi C2. However, the minority shareholder settlement would have made using that or other Wankel engines in Volkswagen models fairly costly, which I think was a big part of why the whole plan ultimately didn’t go anywhere.

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