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    Mazda CEO: No Plans For A Rotary Revival


    William Maley

    Staff Writer - CheersandGears.com

    November 26, 2013

    Some sad news for those hoping for another Mazda vehicle with the rotary engine. Masa-michi Koga, Mazda's new CEO tells Automotive News that for the rotary engine to become commercially viable, Mazda would need to sell around 100,000 vehicles a year.

    "No plans now. It has to be a viable commercial proposition. If we are going to adopt it, it has to be a product that can generate at least sales of 100,000 units a year. We have to be able to achieve a profit," said Kogai.

    Since Mazda pulled the plug on the RX-8 last year, rumors and speculation has been running rampant. Within the past few months, Mazda's former CEO expressed the idea of putting a rotary engine into a hybrid vehicle to generate electricity to charge the battery. There was also the rumor back in August which stated Mazda was hard at work on a new rotary engine that was expected to come out in 2015 or so.

    Now Koga doesn't fully slam the door shut on the rotary engine. He said that engineers are still researching rotary engines as they are able to run on a variety of fuels.

    "We are the first and only manufacturer to commercialize the rotary engine. In that respect, we have some responsibility. So please allow us to continue our research," said Kogai.

    Source: Automotive News (Subscription Required)

    William Maley is a staff writer for Cheers & Gears. He can be reached at william.maley@cheersandgears.com or you can follow him on twitter at @realmudmonster.



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    The DKM rotary has three fundamental problems which make it problematic for use as a gasoline fueled passenger car engine -- problems which cannot be "engineered" away.

    (1) Unlike a piston engine, in a DKM engine the compression and combustion happen at different parts of the torchoid. This is a problem because the heat from the combustion has to be removed bythe cooling system and very little of it is transferred to the next charge. It's like perpetually running under cold start conditions. Emissions suck and thermal efficiencies suffer as well.

    (2) The apex seals which scrape the torchoid walls never ever come into contact with lubricating oil in the crank space. The only ways to lubricate a DKM rotary engine is to burn a pre-mix of oil and fuel, or inject oil long with fuel into the engine. Hence, a rotary engine must (by design) burn oil and have high hydrocarbon emissions from burning oil.

    (3) The DKM rotary is a port aspirated engine, not a valve aspirated engine. As such, the intake and exhaust timings are machined into the housing. Unlike with cam operated valves, intake and/or exhaust timing and magnitude (lift) are not easily variable.

    In the end, while the only advantage it has is it's relatively high power density -- power-to-weight and power-to-size ratios. But this advantage has been eroded by today's high reving or force fed piston engines which achieve in access of 100hp/liter. By the time you ad enough tuned intakes and/or turbocharging hardware to allow the rotary to retain a power-to-weight advantage, it has lost it's size advantage.

    As a matter of fact, the latest rendition of the rotary does not beat the it's contemporary pushrod vee engine in terms of power-to-weight ratio. The 13B-MSP engine weighs 122 kg and makes 238 hp @ 8,500 rpm with 159 lb-ft @ 5,500 rpm. That is 1.95 bhp / kg and 1.30 lb-ft / kg. The LS3 V8 weighs 183 kg and makes 436 bhp @ 5900 rpm with 428 lb-ft @ 4,600 rpm. That's 2.38 bhp / kg and 2.34 lb-ft / kg.

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