• Apr 22nd 2010 at 6:05PM
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Mazda Furai Concept – Click above for high-res image gallery

It's the rumor that just refuses to die. We're not sure if that means there's a whole heck of a lot of truth behind it or not, but once again we're hearing that Mazda is hard at work on a new RX-7 sportscar. And while you might think that making such a vehicle would be as easy as adding a turbocharger to the existing Renesis-powered RX-8 and jettisoning the back seat, Mazda apparently has much more grandiose designs for its next range-topping sportscar.

According to Motor Trend, Mazda's oft-talked-about 16X rotary engine is now capable of running on either gasoline or diesel fuel with nary a difference in performance. We have to wonder about the accuracy of such claims, but if true, perhaps running on diesel or biofuels would give Mazda the eco-cred it's aiming for. In any case, MT says that Mazda is aiming for something north of 300 horsepower with improved fuel consumption, emissions and oil intake over the current Renesis.

As ever, we're taking a wait-and-see approach to these continuing rumors. As much as we'd love to see a new RX on the scene, we're beginning to wonder if it's ever going to happen. In the meantime, enjoy the photo gallery of the too-awesome-for-words Mazda Furai concept.

[Source: Motor Trend]

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    • 1 Second Ago
      • 5 Years Ago
      Heat kills a Rotary. Overheat it and the side seals go.

      The better question is....detonation kills apex seals on the rotary. Diesel packs one heck of a bang. How will the apex seal deal with that?
        • 5 Years Ago
        detonation (knock) is a problem because it actually pushes the apex of the rotor in an unintended direction at an inappropriate time.

        as long as they keep it combusting at the right time, it wont be a problem.

        but you're right diesel is MORE prone to knock, so there must me some engine management advance that is more sensitive or cautious.

        i wonder if the diesel is still compression ignition in a rotary?

        • 5 Years Ago
        Yeah, I found that out when I was racing another car with my old RX2 back in
        the 70's. I loved that car, though.
      • 5 Years Ago
      Rotary engines are the least fuel efficient engines in production one day, but they do have low weight and the best power per liter. They are also quite smoggy for their size and output - they don't meet European emissions anymore.

      Just look at the rx-8... 1.3 liters and drinks gas like a v8.. on top of that.. not known for reliability.

      Would you buy a rotary range extender that got the equivalent of 30mpg vs a piston on that got 50mpg? sure the rotary would be much lighter.. but..

      I dunno why Mazda keeps investing in these rotary engines.
        • 5 Years Ago
        I am trying to find a link for the article but I will just have to repeat as best I can how it went. Basically they took a current RX-8 rotarty and slapped a turbo on it, laid out somewhere around the 315 hp mark and ended up returning 5 mpg more on the test loop they had set-up. Like I said earlier the rotary runs more efficent when its hot thats why a diesel rotary is hard to understand. And your right the reliabilty can be bad but I think it has more to do with who maintains them because I know of and late 80's Turbo model running completly stock with well over 300k on it running fine and just passed the E-test again. Its like any car really take proper care of it and it will last.
      • 5 Years Ago
      I saw a video clip at some auto show and the reporter stated the he Audi A1 hybrid has a rotary engine range extender. If it is true, then Audi sees something in the rotary design.
      • 5 Years Ago
      I'm still waiting for the Mazda EREV using the rotary gen-set, a project
      that Mazda, about 3 years ago said it was working on. I have no idea
      whether they have continued R&D or have abandoned the idea. I
      thought it was a great idea. Bob Lutz told me that the idea of a rotary
      was crazy, and too complicated. I disagree for several reasons. I
      think a rotary is ideal.
        • 5 Years Ago
        Rotary News just posted that Audi is using a single rotor engine for their range extender: http://rotarynews.com/node/view/1083
        • 5 Years Ago
        He thought a 1.4 banger made much more sense. My thought was that you have
        more torque with an engine that has a much smaller footprint. He said, no, the
        rotary is too complicated. Is it? I leave that to you engineers. I would think that,
        on the surface of it, at least, with less moving parts, the rotary would be better
        if only used in generation, and easier to mass produce with less moving parts
        to assemble.
        • 5 Years Ago
        @ Robert - Thanks for the link.
      • 5 Years Ago
      Yeah, we know all the problems; but it's just the generator, guys, it's not like it's
      pulling load.
      • 5 Years Ago
      The Rotary running on diesel would be awesome! The only thing I can see being a problem is that rotary engine seems to run better the hotter it gets and diesels run fairly cool so it begs the question can it run properly?
      • 5 Years Ago
      I LOVE the Mazda Furai Concept. Tesla was smart to grab Franz Von Holzhausen.
      • 5 Years Ago
      The Renesis displaces 2.6liters. The 1.3liters was half of the housing which is like saying half of the stroke on a Piston is the displacement. I'm sure a Rotaryguru could explain it better.

      And the displacement has less to do with the Rotaries fuel problems, the combustion chamber is styled to last not to be efficient. My little understanding of the Rotary is that the Compression Ratio is effectively maxed around 11:1. The Rotary gets it's HP from it's ability to Rev and it's moderate displacement. Considering it really only gets 88BHP per liter of displacement it's okay but to take advantage of the high revs the gearing is extremely short and close ratio and so the fuel economy is terrible.

      I like the RX-8 chassis design and the body is fairly good but it's too heavy to be a compact, it's more like a Midsize in weight and the Aerodynamics are good .30 in the newer version. The Renesis is lighter than the RX-7 13b but the weight is almost exactly the same as the Mazda MZR line of 4 cylinders. If they built a 2.5liter MZR to redline at 9kRPM the HP would undoubtably be the same but the fuel economy would be slightly better as they could use a higher compression ratio on Premium Fuel and probably more HP on top of that. But the Rotary is their baby and is "special."
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