OT: American race cars (formerly - OT: new car advice)

[Robert N. Eaton]

Dan Lund wrote:
> I think it's pretty amazing that I just learned more about the Wankel
> engine design and use on a Linux mailing list than I ever have while
> reading about them for years!
> (not complaining, I'm actually finding it interesting!)
>
> --Dan
>
> On 11/22/05, Mike Garfias <mike at garfias.org> wrote:
>
>   
>> The production car stuff never really did that.  Also they tend to not make
>> the low end torque, and that requires putting lower gears in to get the
>> performance.  The engine does have to spin to the moon to go.  Also, the
>> wankels while making lots of power for their displacement, are pretty fuel
>> inefficient.
>>     
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>   
The Wankel engine had vaguely triangular rotors flopping about in 
vaguely figure-eight chambers. At the apexes (apices?) of these rotors 
lay their downfall: the apex seals. These were (at first) simply soft 
steel bars in slots, forced into contact with the trochoidal chamber by 
simple flat springs beneath the bars. These were supposed to perform all 
the functions done by the various piston rings, compression, oil 
control, scraper, etc. That this system worked at all was amazing; that 
it worked as well as it did was astounding.

The problem with these apex seals was that at rpms over, say 10 grand, 
these seals would chatter.  The chattering would cause the chromium 
plating within the trochoidal chamber to flake off, resulting in a hot 
smoking paperweight instead of an engine.

To combat this, Mazda hot-rodders stole an idea from the two-stroke 
motorcycle guys. When two-strokers were searching for more rpms without 
piston ring chatter, the hit upon the Dykes ring, which had a T-shaped 
cross section.  This allowed some combustion gasses to get on the 
underside of the ring, forcing it into firmer contact with the cylinder 
wall. This worked fairly well for the two stroke racers.

The somewhat T-shaped apex seals allowed racing Mazdas to exceed 13 
grand without destroying themselves.

Rolls-Royce did considerable research into the Wankel design, trying out 
various exotic materials for the apex seals, including man made rubies 
and even man made diamonds!  They gave it up as a bad job, as even they 
were never able to conquer the apex seal problems.

Bob Eaton