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Interesting Engines: Mazda’s R26B

October 6, 2012 by Matt

Mazda R26B 4 Four Rotor Engine Motor Le Mans Win 787B

Mazda’s 4-rotor, 2.6l, 700-hp R26B is the only engine by a Japanese manufacturer to win the 24 Hours of Le Mans race outright. In doing so, Mazda scored an achievement that has always eluded such pillars of the Japanese racing scene as Nissan, Toyota and Honda.

The year was 1991, and Mazda had something to prove. Perennially stung by criticism of their signature Wankel engine as an unreliable gas guzzler, the automaker had long sanctioned factory entries into endurance racing series across the globe. And though Mazda had achieved a remarkable amount of success through the years in that form of racing, Le Mans stood as the unconquered peak, the title that would perhaps finally demonstrate, to the racing world at least, that the rotary engine deserved to taken seriously from a competition standpoint.

The ultimate incarnation of a long series of endurance-focused rotaries, the R26B built on the foundation laid by its 4-rotor predecessor the 13J-M, itself a variation of the 3-rotor 20B, and added a number of refinements. At its core, the R26B was a basic non-turbocharged rotary engine, but with racing-derived features like intake ports on the periphery of the rotor housings instead of on the side plates (as in all production Mazda rotaries), an arrangement that produced a great deal of overlap between the intake and exhaust “stroke” of the rotor but which allowed for much greater airflow potential at high rpm, where racing engines live.

Mazda R26B 4 Four Rotor Engine Motor Le Mans Win 787B Diagram Schematic Drawing Cross Section Cutaway

Also, the R26B was fitted with steplessly variable intake runners, able to optimize intake length and thus airflow seamlessly for any engine state, as well as 3 spark plugs per rotor instead of the usual 2, promoting more uniform burn of the fuel-air mixture. The engine was capable of cranking out 900 hp at upwards of 10,000 rpm, but was detuned to “only” 700 at 9,000 rpm to in the interests of durability.

Mazda R26B 4 Four Rotor Engine Motor Le Mans Win 787B Cutaway Drawing

And it worked. Fitted to a durable, proven 787B prototype chassis and driven by the trio of Johnny Herbert, Volker Weidler and Bertrand Gachot, the R26B vindicated Mazda’s efforts once and for all at Le Mans in 1991. Perhaps sweetest of all were the primary reasons for the win: Not power, where it was outclassed by the Jaguars and Mercedes running that year, but fuel economy and durability, two attributes which allowed the R26B-powered 787B to keeping lapping the circuit longer and shrug off failures that sidelined other teams. It’s an amazing engine, and Mazda is rightly proud of their success.

To see 1991 Le Mans winner Johnny Herbert driving his race-winning 787B just last year, click here. It’s a spine-tingling clip.

Editor’s note: This post is part of an ongoing series examining unique and significant powerplants. Read the other installments here:

Filed under: Interesting Engines, Mazda, Racing, Rotary, Technical

7 Comments

  1. John D says:

    That sounds amazing. I bet power delivery doesn’t get much more linear than a naturally aspirated 4 rotor engine with peripheral ports. I’d bet it’s pretty smooth, too.

    On a side note, I recently spoke with the gentleman who purchased my FD a few years ago. He has done quite a bit of work to it (v-mount, 285 width wheels on all corners, Japan spec front end and rear diffuser, fresh paint job…either black or very dark montego blue) and has it up to about 500 rwhp (so he claims). It is now saddled with a single turbo pushing ~25psi and has been reliable for him all this time. I think it’s safe to say he has the most bad a** car in Colombia, MO. He called me to verify the specifics of the engine rebuild (that occurred before I purchased the car) because he’s thinking of turning up the boost and wanted to know if that would be feasible considering the parts that were used. Crazy. But anyway, I was astonished that it was holding up so well. Just confirms my earlier suspicion that I had a good one…

    • Matt says:

      I’m sure your assessment of the engine’s power delivery is right on, and I’ll bet that contributed to its durability and helped lessen driver fatigue during the 24 hour race, too.

      Neat about your FD! You did get a good one; I knew because Ashraf only had one or two negative things to say about it rather than his usual laundry list, haha! :) Does the new owner have a website or build thread somewhere?

    • Aaron says:

      …And I’m still kicking myself for not thinking to ask you to keep me in mind when you were ready to sell it :)

    • Aaron says:

      Great mechanical soundtrack to that video!

  2. dragon xp says:

    Mazda is the only car company with balls of titanium who ventured in an unknown territory which is the Wankel i wish they return and make them super efficient. keep up the good work

  3. Ard Michielsen says:

    Mazda 787b’s win at Le Mans 1991 wasn’t the only remarkable victory of a rotary engine in endurance racing. The RX7 won the 24 hours of Spa-Francorchamps 10 years before with drivers Pierre Dieudonn√© and Tom Walkinshaw. And the 717C won in the C jr class at Le Mans in 1983 with Takashi Yorino, Yojiro Terada and Yoshimi Katayama.

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