Once again, I'm going to refer to something I read from the Racing beat tech catalog.

They claim there is a shape difference between the GSL-SE 13B & all of the following 13B's. They go on to say that rotor/housings from a GSL-SE cannot be used with rotors/housings from later models.

I don't have the book here in front of me, but I swear that was the point they made.

 

They say that, yes.

However, why would the GSL-SE rotor housing shape be different from the 12A's? Or rather, why would the GSL-SE's rotor housing be different from the earlier 13B's, of which all '85-earlier 13B's are just '74-up 12As with 10mm wider rotors?

Believe me, I was expecting to find a difference when I mated the housings together. I was shocked to find none. I went around the circumference for a half hour trying to find a spot where there was a spot where one housing was deeper or shallower than the other and I did not find one. Mind you I'm expecting the difference to be maybe .002-.005 or so, I'm not looking for something earth-shatteringly large. I found *nothing*.

To reiterate, why would Mazda have one dimension for the 12A, have a second dimension for the 13B *which was designed and produced at the exact same time and used most of the same parts, and had the same eccentricity and seal geometry*, and then redesign the 13B using the 12A trochoid dimensions?

 

Speaking of trochoid differences, I'm going to mate a '73 12A rotor housing to a '74-'85 13B housing to see if there are any differences.

 

Well like es said this is something he read and I don't doubt it. It also wouldn't be the weirdest thing Mazda ever did.
I never figured out what they were trying to accomplish when they put the o-ring grooves on the side plates instead of the rotor housings.
If they would have left that alone we could be using 12a sides with 86 up rotor housings instead of trying to find TII housings

 

CORRECT ME if I am all wet!
but why would the oring groves mater
just fill one grove with moglease or jb weld and surface grind it flush
wouldn't that work ?
I have used that to fill water and oil ports on ford 351 big block heads
so they can be put on a 302 block small block

Just wanting know why not just like a littel kid
I won't know unless I ask

 

Because the best scenerio would be to have 12a side plates that are abundant, and 86 up rotor housings which are abundant compared to pre-85 13b's.
Neither of these have grooves at all. No grooves=no o-rings= bad thing.
having grooves machined is not cost effective for most people.

 

I gess I don't always belive every thing I read
sometimes I want to know why
you see the world was not flat it turned out round
maybe I will do something like fall of the end of the world because I don't fallow someone's know fact?

 

SHHH!!

That's something I was going to try to do The old Series 4 center plate in a 12A to make OEM tye injection simpler gambit....

However if you wanted to do something like Scallawag mentioned IE put early side housings in a late engine, you couldn't easily do it because there would be O-ring grooves at all - 12A sides have no grooves and '86-02 rotor housings have no grooves.

For an FC you ideally have an FC center plate and for an FD you ideally have an FD rear place, since in those cases those plates are the ones that have the motor mount attachments. FBs and earlier can use any ol' engine since they attach via the front cover. This is for bolt up arrangements obviously, if you are handy with a welder, a saw, and a tape measure, you can mount any engine anywhere.

 

Mazdatrix doesn't seem to believe the RB catalog either, they will make '85-earlier engines with 2mm seal rotors for you no problem.

 

you can buy ceramics to coat cylinder walls/cylinder heads, valve faces, rings etc.. For reletively inexpensive and is supposedly a bake on style process.

Perhaps you can machine an extra tolerance in the housing, then apply ceramic, then re-machine the housing and polish to spec?

 

this is odd, i built a new motor for my comso with
gslse rotor housings and 86 rotors seems to work just fine.

matt

 

Well it took 3 days and various hours of off and on reading to read all of this.. Very interesting stuff.. My applause to you Scal for all of your research, etc. I do not understand all of this but the size of the pores in the new coating conceren me with them being larger than the ones from mazda. Another thing i think this thing needs to be bench tested for 100k+ miles or at least try. GL with everything else..
Derek

 

Yeah, if you can see the pores with the naked eye they are bloody massive compared to factory. Would this mean the mixture would need more oil to properly lube the aapex seals?

 

Scalliwag
Some large company needs to give you a good paying job doing what you love! You obviously have skills and thinking ability...GL with all of it.

This has been very interesting reading. I don't post very often, but I read a lot....and this is one of the few threads that actually absorbs my attention.

I am in the middle of an invention that will NEED to use the machining and ceramic coating process (or something similiar) so keep at it!

 

Thanks for the kind words I have a really good job it just does not involve anything related to this, computer support for military contracts. It pays pretty well, very stable, very challenging because of the demands, and there's lots of good looking women at our main facility that I am at
I am taking a week vacation starting Thursday that was intended to go to Sevenstock. Since I got a new paint job, interior, and misc. other things done on my AE it does not appear I get to make it though. Spent so much so quick my wife is really pissed that I am talking about a trip to Cali now.
The only good news is that I have a week to work on projects if I don't get to go
So we'll see what happens.

 

Your welcome on the comments, as for the other well, sounds like my wife too.....hahaha.....

I was actually looking for a nice AE to put my Cosmo RE in, but alas she said she hates that body style.....she does like the 3rd gen however, sooooo....I am tracking one down as you read....yea! Sometimes it turns out for the better when she wants something Gotta look on the bright side...

Hey think of it this way, u get to have some time with your 7 either way.......just better get in some time with the wife too eh? hehe....yep....nothing like car envy to really get a woman going...ahahahaha. Anyway....

I will be watching the thread for any more news....and sorry, but I don't have any real contacts or productive info to add to the thread....o well, if I do find any I will be sure to send it your way....later,
Greg

 

Hey I am looking into an AE with 13b bridge, what kind of reasearch have you done? I maily need to konw what the curb weight is on an AE and how much does the stock motor weigh and what is the stock weight distribution?

 

I think Mazda rotary parts are fairly cheap in Japan. I guess over there it is like small block parts here. But again they are probabily complaining about V8 stuff being expensive. I have put early style rotors into 86 and up rotor and side housings and both times the motor has just one chamber that is low on compression??? I can never figure that one out.....

 

I have it from pretty good sources, that for high performance use,its best not mix parts from even different production runs of the same motor, I just finished a 3 week tour of the top shops in Japan, on more than occasion I was told to use rotors and rotor housings from the same production series, as even over a year the housings shape tends to differ a bit, and the rotor tolerances change from production run to production run, 2 places I was at, have their assembly rooms, set up so that the temperature in the rooms is the same temperature as the machine rooms at Mazda's engine plant, to keep tolerances exact, to them that was what made the difference between a motor living at 10000 rpm for 5 minutes and one that will live for 5 hours was all about..
I saw rotors from a 13bt, 13brew,20b, and an earlier 13b all side by side lined up with a straight edge, and they were not all the same shape or even all the same curve along the face, there was a visible difference among all the parts...
I guess it depends on what you want out of the motor, and how hardocore you are....Max

 

were they used rotors?

 

it shouldn't have mattered if they were used since the only areas subject to wear would be the slots for the apex and side seals and oil control rings.
This is very odd and for the life of me I cannot fathom why they would make changes to those areas that would require retooling at the factory. But I have seen stranger things.

 

I have all of the above on the bench right now I will have to line them
up and take a look, will post what i see in a few days

matt

 

its very hard to get the rotors all lined up on a bench consistently. we have a line up of rotors and they look like they are all different too, but thats just sitting on the ground in a row.

mike

 

Other than schiskabobbing them with a round bar the same diameter as the ID of a rotor bearing and setting up something to index the rotors to the same position I would not know how else to accurately measure that.

 

Your weight distribution with a 13b bridge should be close to the same as the stock AE which is 2850lbs or so and 50/50 weight dist...

The engines would basically be the same depending on if you are going to run a turbo on that or carb it or whatever...all the other weight will be the same except for what you remove. If you do exhaust along with that mod then the weights should even out....

Check this site for specs:
http://home.earthlink.net/~icemark/FCseries4.htm

You should have no problems with mounting, but you will need to do a considerable amount of research to get the right combination for it to run properly....you can't run that with the stock computer. If you already know that then I am sorry, but that is all the help I can offer from here....

Do some searches and read everything you can find before starting that project.....good luck.