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Wankel Rotery Automotive Engines seemed to be a good idea in practive turned out not to work out so well

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Posted by BaltACD on Thursday, May 25, 2017 8:27 PM

erikem
I don't see any chance that there would have been RR applications of a gasoline burning Wankel engine other than MofW. Rolls-Royce was working on a diesel Wankel using a larger rotor for pre-compression, but I suspect that too much heat got lost during compression and expansion due to the much higher wall area to volume ratio in the Wankel design versus a piston engine.

I would expect the higher compression ratio needed for diesel operation would have played a number on Wankel seals.  Sealing has been a problem on gas engines at a much lower compression ratio.

Never too old to have a happy childhood!

              

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Posted by 54light15 on Thursday, May 25, 2017 2:06 PM

In Germany, the NSU company made cars with Wankel engines, the NSU Ro-80 was a mid-size car about the same as an Audi. NSU was a division of Auto-Union which also made the Audi, Horch, Wanderer and DKW. The Ro-80 had problems with the seals too but any ones left on the road have been upgraded. Mileage was never good in those but I'd still own one. The Ro-80 came out in the late 1960s and it's looks haven't dated. 

RME
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Posted by RME on Thursday, May 25, 2017 10:02 AM

The Wankel rotary [note sp.] worked out just fine; the Japanese did all the necessary work on the tip seals (and in the process greatly advanced our knowledge in several fields).  The specific thing that killed development at GM was the emissions problem inherent in the large swept wall area, which (at least at that time) could not be kept from quenching some of the combustion, and I believe had additional issues of intrusion of engine lubricant into the combustion chamber.

Railroads do not value 'smaller and lighter' powerplants, in general, nor do they value the ability to make high horsepower through very high cyclic rpm.  (One person racing Mazda rotaries said that if you let the little red 'overspeed' light that came on at 9000rpm go out, you weren't being competitive enough...)  On the other hand, railroads do value extreme fuel efficiency, which is never going to be something a trochoidal expander with inherent internal combustion is going to provide anywhere near as well as a diesel crosshead engine.

The Wankel engine involves complicated steps to manufacture some of its components effectively; some of this is abated by the ability to make greater hp just ber 'stacking rotors' but you still needed considerable tooling and perhaps process changes to make the engines 'for production' -- this was much harder to do in the '70s, in the infancy of CNC, and is still probably expensive (relative to, say, using the Koenigsegg valvetrain on a dynamically-balanced piston engine). 

There is also some question concerning the whole of the engine life cycle:  when it gets higher hours, or isn't maintained correctly, the things that can go wrong with it, the failure modes it can experience, etc. are often different from comparable conventional piston engines.

The way I look at this and similar concepts like the Quasiturbine (which is not a turbine) is that they fit into a particular niche, with performance and packaging combined, somewhere between the positive-displacement piston engine and the ceramic/cermet turbine.  If emissions weren't such an important 'modern' consideration I suspect you'd see far more of the design ... in automobiles and other lightweight applications like APUs or gensets.  We are just starting to get to the point where 125mph locomotive design might benefit from modular Wankels of the type I proposed in the early '70s (as an alternative to modular turbines, in a rebuilt E-unit chassis of all things!) but I cannot imagine one of these engines meeting Tier 5 emissions without so much aftertreatment as to make you cry.  (Well, cry even harder thn you would for other powerplants...)

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Posted by erikem on Thursday, May 25, 2017 9:58 AM

I don't see any chance that there would have been RR applications of a gasoline burning Wankel engine other than MofW. Rolls-Royce was working on a diesel Wankel using a larger rotor for pre-compression, but I suspect that too much heat got lost during compression and expansion due to the much higher wall area to volume ratio in the Wankel design versus a piston engine.

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Wankel Rotery Automotive Engines seemed to be a good idea in practive turned out not to work out so well
Posted by CandOforprogress2 on Thursday, May 25, 2017 12:39 AM

The rotery engine was to be used not just for cars but other industrial applications however the seals gave out prematurely. Any of the engineeers here can tell me more about this engine and could it have railroad applications? As far as i know only Mazda used the engine and AMC Pacer was to use it but changed at the last minute.

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