By on October 15, 2017

Mazda RX-7 FD

Mazda never gave up on the rotary engine. Despite putting it on hiatus after the RX-8 ended production in 2012, the automaker has continued developing rotary-based solutions to achieve locomotion. There has even been a longstanding promise that a Wankel motor would eventually return in a future sports car that would trump the MX-5 in outright performance. However, Mazda never mentioned when the world could expect to see another rotary in action.

Then Mitsuo Hitomi, Mazda’s global powertrain head, gave us a timeline to sink our teeth into. The year of the Wankel will be 2019, but it’s not coming back how you imagined. Instead of dropping it into a high-revving performance vehicle, Mazda thinks a rotary would make the perfect gas-powered range extender for its upcoming electric vehicle.

“I think that’s probably what it will be,” Hitomi told Automotive News during a sneak preview at the Japanese carmaker’s Japanese proving grounds.

According to Hitomi, Mazda Motor Corp. feels that the rotary’s ability to make gobs of power in a small, low-vibration, package would make it an ideal range extender on its first battery-powered car. But it also serves as a nod to the company’s heritage and keeps rotary R&D alive.

Akira Kyomen, program manager for vehicle development said the new EV would come in two flavors — purely electric or equipped with a charge-supplementing generator. Mazda’s plan is to market the basic EV in Europe, Japan, and China but acknowledged that North Americans clock more daily miles on average and would appreciate something to alleviate range anxiety.

Mazda says its new EV architecture, set to arrive in 2019, will accommodate BEVs with or without range extenders — as well as hybridized powertrains. But what of that ultra-powerful rotary-driven performance vehicle we keep hearing about?

While Hitomi confirmed that Mazda’s engineering team has continued work on a larger Wankel, he also said the company had to prove there would be sufficient room on the market for the vehicle it would go into. The automaker doesn’t want another sports car if it is just going to cannibalize Miata sales. Hitomi said the company needs to assess “whether the business conditions will be met or not … not the big technical issues. Are we going to really sell that many models of sports cars? There aren’t that many auto companies selling multiple sports cars.”

We can think of plenty of manufacturers that produce more than one performance-oriented vehicle, but Mazda is right to be cautious if it isn’t going to make something exceedingly different from the MX-5. That said, we all assumed the next rotary-equipped performance model to be a fire-breathing RX that would easily upstage the Miata and distinguish itself on the market.

However, Mazda has been exceptionally tight-lipped on its plans for the rotary while also making time to nudge journalists with constant reminders that something is in the works . Most of the rumors about Wankel engines were launched by the automaker to begin with, including early hints that their first EV would use a rotary-based generator.

Questions remain as to how feasible the powertrain even is on a modern performance model though. The RX-8 left the market for two reasons: dwindling sales and tightening emissions standards. Mazda has said in the past that it has been fine tuning the rotary so it will be ready whenever there is an opening for it. But how it can make one work without burning through gallons of fuel or belching tons of carbon dioxide is unknown. Perhaps that’s why it’s decided to focus on the range extender first.

Although, Mazda’s reasoning for holding onto the rotary runs deeper than just tradition. It knows enthusiasts still love it and doesn’t want to give up on what it sees as a piece of its soul, even though it has been pretty wishy-washy on the rotary’s future in the past.

“The technology of the rotary engine is something only Mazda can build,” said Mazda’s global design chief Ikuo Maeda during last year’s unveiling of the RX-Vision Concept. “If we give up, it’ll disappear, and that’s a huge risk as engineers won’t be attracted to Mazda. [Head of R&D Kiyoshi] Fujiwara wants to build a rotary and a sports car, and I have the same feeling: a grown-up sports car that can lead our brand — an icon.”

“A car needs to have character, which means it has to convey that traditional machine-like feel. It must still have a mechanical quality,” Maeda concluded.

[Image: Mazda]

 

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29 Comments on “Mazda’s Rotary Engine Returns for 2019 — Just Not How You Had Hoped...”


  • avatar
    Jack Denver

    A properly designed “range extender” can also drive the wheels directly as a power booster to supplement an electric motor (as in the Volt). When they are both running at the same time, you have a lot of power available – all the power of the electric motor PLUS all the power of the gas engine. So there’s your (hybrid) rotary sports car power plant. I don’t think there’s enough room to fit all this stuff in a Miata so they would probably have to put it in a different car – presumably their future electric platform.

    • 0 avatar
      stuki

      Hybrids are great for many things, but with any kind of battery capacity, they quickly get too heavy for a proper sports car.

      • 0 avatar
        notapreppie

        From this comment can I assume that you put the Maclaren P1, Ferrari La Ferrari, Porsche 918, BMW i8, and Acura NSX in some category other than “proper sports car”?

        • 0 avatar
          stuki

          They’re GTs. Or Supercars. Or overweight, puffy, pimped out racecars for pimps… Very different from a traditional “sports car.”

          If you absolutely want to shoehorn them into the sports car category, I guess one could argue they are compensating for the gratuitous weight gain inherent to multiple engines and fuel storage modules; by building them, or parts pf them, out of carbon fiber and other lightweight exotica. Either way, they’d be more sports car’ish, if they ditched some weight.

  • avatar
    mike978

    Good on Mazda working through the engineering issues. I expect the usual suspects(s) will complain. Even though Mazda is profitable, has a well received line up and has globally growing volume (and ATPs).

    That said they do need to have a higher powered CX5. Maybe the 2.5 turbo. Or one if the new engines debuting next year on the new 3.

  • avatar
    Ermel

    I’ve been waiting for a Wankel range extender. Audi had it in a showcar a couple of years ago; it figures that Mazda would be the ones to actually make it happen.

    • 0 avatar
      BuzzDog

      Same here.

      Back in the days of the Great Recession, and the simultaneous condition of high fuel prices, there were a number of speculative articles on the use of turbine and Wankel engines in hybrids. I’m no engineer, but I seem to recall reading that these types of engines are most efficient when run at a constant RPM (which could be more easily accomplished in a hybrid), and there is a benefit of compact size as compared to a piston engine.

    • 0 avatar
      Garrett

      I would rather have a diesel range extender.

      At the end of the day, a range extender is a glorified generator that is built into your car.

  • avatar
    romanjetfighter

    nice

    rotary engines and zoom zoom performance went from reason you’d buy a mazda to a marketin gimmick to sell EVs

  • avatar
    ToddAtlasF1

    Wankels are compact and light, which is good. OTOH, they don’t produce much power per gram of fuel burned, and they are difficult to make run cleanly. I wouldn’t be surprised if this is as big of a success as Mazda’s diesel.

    Anyone know why Mazda never simply stuck the Renesis in the Miata? 240 hp and lighter weight would have made the Miata a Boxster destroyer. Emissions standards have tightened, and CAFE made gas guzzlers expensive, but there was a window for a giant-slaying rotary Miata.

    • 0 avatar
      TonyJZX

      My assumption would be that the wanker supplementary extender does two things…

      A. once the car uses the torque from the electric motor to get up to speed, the rotary only does hwy speed power, something the electric motor is not good at

      B. the motor only runs at its most efficient rpm to provide power to the batteries

      so if the rotor only works in a restricted power band slash rpm then doesnt it make things like consumption emissions and sealing easier?

      this was the way the original design spec of the Volt Version 1.0 was supposed to be.

    • 0 avatar
      WheelMcCoy

      “Anyone know why Mazda never simply stuck the Renesis in the Miata?”

      I’ve read on the miata forums that it’s more than an engine swap. The crank shaft on piston engines is down low, whereas it is near center on a rotary engine. That means you’ll need clearance in the transmission tunnel which suggests a chassis redesign.

      It’s not an insurmountable problem, but add the disadvantages you cited — emissions and thirst — and it all adds up. Besides, a naturally aspirated engine is traditional in a Miata; it works very well and is easy to maintain.

      • 0 avatar
        ToddAtlasF1

        I’ve got a 13B on a bookshelf. The output shaft isn’t higher than a typical piston engine’s. Just look at the oil pan on a piston engine compared to a complete rotary engine. The RX8 design mules started out as Miatas, so I believe Mazda had the resources to make rotary Miatas if they cared to.

        • 0 avatar
          sportyaccordy

          Given how much of a disaster the RENESIS 13B was I’m gonna say the omission was a good thing. More HP is not worth engine rebuilds and Russian roulette reliability.

          • 0 avatar
            nlinesk8s

            +1 the 12A cars of ’84-’85, if well maintained, had a good engine life. The 13B’s had leaking injectors that diluted the oil, and wore out about 130k (fanboys will point out longer running examples, but typical life is typical life) I owned both generations.
            The renesis goes 90-130k before engine replacement, assuming a stock setup, and tho’ I’d love to have an RX-8, I can’t bring myself to toss the dice on one.

  • avatar

    How rotary engine is more effective that Atkinson-cycle engine in hybrid vehicle? If it was then Toyota and Ford were using rotary engines in their hybrids. I think Mazda is desperate. But don’t worry Japanese government and Toyota will help them out.

    • 0 avatar
      bunkie

      It has a smaller physical volume for a given power output. When you consider that by adding a second power source space utilization becomes a factor, this is an advantage.

    • 0 avatar
      bunkie

      Also, Toyota and Ford don’t have 5 decades of experience with the Wankel. That sort of domain knowledge is hard to duplicate.

      Aside from emissions the big issue with Wankels is their inefficiency, as you have pointed out by making a comparison with Atkinson-cycle piston engines. Most of this is heat loss through the exhaust and cooling systems. Theoretically, this heat can be recovered, but it complicates things which tends to defeat one of the major points of the Wankel, its simplicity.

    • 0 avatar
      notapreppie

      My guess is that there are benefits from a packaging perspective. A single-rotor engine could be pretty compact.

      Also, there may (or may not) be significant gains in efficiency if the rotary engine were engineered from the beginning to run at a set RPM.

      Besides, the idea of a range extender is that you should only use it very rarely and for short periods of time. BMW’s i3 is setup this way; it’s a plug-in electric vehicle with an emergency generator and 1.x gallon fuel tank that’s designed to get you to a charging stating in an emergency.

    • 0 avatar
      WheelMcCoy

      Agree with what @bunkie stated.

      The rotary in the RX-8 is equivalent to a 1.3 liter engine and produces 159 pound-feet of torque (and 212+ HP). It can fit into approximately 1 cubic foot. Weighing less than a similarly spec’d piston engine, it helps reduce the load on the battery.

      So yes, there are some small advantages. Mazda is also leveraging their rotary experience, as well as their traditions and identity.

  • avatar
    Land Ark

    Don’t rotaries have a habit of flooding and not starting if you turn them on and don’t let them fully warm up? Or were they able to resolve that in the later versions of the RX8?

    That seems like something that would be an issue if using it as a range extender.

    • 0 avatar
      bunkie

      I never had any issues with my 1980 RX-7. And, believe me, no engine warms up faster than a Wankel. Too little heat is never a problem.

    • 0 avatar
      notapreppie

      I suspect most of the RX-8s that had this issue were on the more anemic battery/starter combo that shipped in 2004/2005 cars.

      My 2005 RX-8 has never flooded but Mazda updated my starter and battery early in my ownership.

  • avatar
    slavuta

    “rotary’s ability to make gobs of power in a small, low-vibration, package”

    HP but not torque, right? Also, it drinks too much gas and chases it with oil. Are they planning to solve these issues?

    • 0 avatar
      notapreppie

      Torque really isn’t a concern if you’re just driving an alternator.

      One of the problems creating the thermodynamic inefficiencies of the rotary engine has to do with how the rapidly changing shape of the combustion chamber affect the flame front. It’s possible that engineering the whole system to run at a single or smaller range of RPMs would yield significant improvements in fuel economy.

      For instance, the Renesis engine has different sets of fuel trims for three different ranges of MAF measurements (IIRC, 0-8 g/s, 8-20 g/s and 20+ g/s). That sort of complexity goes away if you engineer the system to just run at 3000 RPM.

  • avatar
    Felix Hoenikker

    I always thought that a gas turbine with a regenerative heat exchanger is the way to go for range extenders. The big problem with turbines is their high fuel consumption at low power, but this goes away if you set it up to run at the optimal rpm and power output and use it to power a generator. Also, the unit could be very compact relative to a piston engine.
    I guess it’s a cost issue.

  • avatar
    SCE to AUX

    “It knows enthusiasts still love it and doesn’t want to give up on what it sees as a piece of its soul…”

    TTAC is that people really aren’t hungering for rotary sports cars.

    The late RX-8 sales dwindled steadily (~-50% annual rate) for 8 long years:
    2004 = 23690
    2005 = 14673
    2006 = 9343
    2007 = 5767
    2008 = 3368
    2009 = 2217
    2010 = 1134
    2011 = 759
    2012 = 80

    Mazda is self-deluded about bringing the rotary back in *any* form. It makes no sense as a range extender due to emissions. And any range extender has to be done like the Volt, where you get plenty of power from the ICE, and not like the BMW i3, whose range extender can’t really propel the car.

    Mazda’s fixation with rotaries is one reason this company’s US market share is shrinking. They ought to spend their limited resources on winning back the US market.

  • avatar
    Lorenzo

    Funny that the rotary engine, originally thought of as primary propulsion, ends up as an auxiliary. The Chrysler turbine followed the same route, used for forced induction of an ICE. Does that mean somebody might find a better use for a CVT?


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