# Mazda Adapts Rotary Engine as Electric Car Range Extender



## EVDL Archive (Jul 26, 2007)

Rotary-engine generator would, like the BMW i3 REx system, double the range of the Mazda2 EV prototype.

More...


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## PhantomPholly (Aug 20, 2008)

As a generator running at a constant RPM, the Wankel might have pretty good efficiency. A shame it never competed well with pistons.


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## Frank (Dec 6, 2008)

You've never driven an RX-7 I guess...


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## Duncan (Dec 8, 2008)

I would have to agree with the Phantom here,
The problem with the Wankel is expansion ratio,
The basic geometry restricts the amount the gasses can expand and do work before being exhausted

This means there is still a lot of wasted energy in the exhaust - leading to low thermal efficiency and a hot exhaust

Rolls Royce did some work on a two stage Wankel about 20 years ago - nothing seemed to come of it

You can get lots of power out of a Wankel - but it takes a ton of fuel


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## PhantomPholly (Aug 20, 2008)

Frank said:


> You've never driven an RX-7 I guess...


Many times - ultra smooth, good power to weight, only real downfall was less efficient.

Moller has been working on them for decades, and has created small but efficient rotaries.


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## Karter2 (Nov 17, 2011)

From the Mazda spokesman...


> “We are the first and only manufacturer to commercialize the rotary engine,”


 where do they get this idea from ??
Have they forgotten NSU ? never mind Wankel themselves who marketed various sized versions up until recently !
Then there is Moller/Freedom and numerous other manufacturers of lawn mowers etc.
And then there are Italian (Parrilla) and German (Wolf /Aixro) companies that make compact but very powerful ( 200cc, 65+ bhp) rotaries for kart racing , microlights, paragliders etc,








The Wankel has a problem with thermal/fuel efficiency, but it still has huge advantages in power/weight and power/volume ratios.


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## PhantomPholly (Aug 20, 2008)

Karter2 said:


> From the Mazda spokesman...
> where do they get this idea from ??
> Have they forgotten NSU ? never mind Wankel themselves who marketed various sized versions up until recently !
> Then there is Moller/Freedom and numerous other manufacturers of lawn mowers etc.
> ...


It's called "Marketing Hype." They set an arbitrary number of units (which they have already produced) as the measure for "commercialized" and then it is the truth....


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