I've seen a pic of the three hole exhaust. Weird. My twin dizzy housings have normal ports. They're ported pretty tall.

 

It the US the RX-3 came w/ a 12a or a 13b (in the RX-3 SP) only US car w/ the 10a was the R-100 ( we never OFFICIALLY got the Cosmo 110s here though a few were imported by dealers)

 

The US version of the RX3 SP had a 12A.
Good god, the flailing never ends around here, LOL.
The SPs DID have a different port configuration, though.
IIRC the secondary ports were in the center housing as opposed to the side housings, and the intake manifold was changed accordingly.

 

Makes one think..so many changes.
A bit of learning if you want to hear ir off by heart!

I have seen quite a few MFR 12A PP housings.Even some brand new,never used ones.

 

man! i though i was a rotary fanatic! i have read all the posts in this thread and you are all very knowledgable on the old school cars.... i even learned some new stuff
maybe you guys could be al ittle nicer to each other?

 

Problem seems to be that Mazda made way to many versions of those early rotaries... Obviously, this was normal in those early days of rotary development.
However it's rather weird why engine configurations differ so much from country to country.
For an example: the EU version of the RX-2 had a rather different 12A then the US one, hence the earlier confussion on power output. The ones overhere had more power then the later 12A RX-7's, with about 120hp.
Then there's the very strange fact that they had different names all over the world, making it very complicated to discuss this matter. Especially the Cosmo name is such a thing.
I suggest this link for those wanting to learn some more:
http://www.der-wankelmotor.de/Fahrze...ZDA/mazda.html
It's in German, but can easily be translated with some programs, I think. Mind you, before you all start writing about how wrong they are: remember, it's about the cars we got (Europe) or else the Japanese versions.
These specs can differ rather seriously from what you guys got.

 

It just doesn't kick in my head how is it possible to have 3 holes for the exhaust. Were they just really small? Was that supposed to create more velocity?

 

Probably. Cheeseport exhaust, anyone?

 

I'm guessing that the three holes was to cut down on noise and emmissions, and maybe fuel consumption. It was during the "oil crisis" of the seventies.....