Hey

I need insight https://www.nopistons.com/forums/pub...IR#>/smile.gif



Im having a hard time finding rotorhousings for my 12A turbo build-up.

Reason is: I need perfect ones with NO cromeflakeing what so ever, used housings all have that unless they are from an Rx-2(carbon seals right?)

I been told the Rx-2 housings wont last long with steel seals, now that sucks :-( https://www.nopistons.com/forums/pub...IR



My idea on which i need insight is:

I have plenty 13B rotorhousings in great shape, could i mill them down to 70mm and use them with a 12A motor?

I have the skills, CNC mill and template to do the waterseal grooves.



Sure new 12A housings are available everywhere cheap, but shipping and import taxes would ruin me(Denmark)

For reference, ONE rotorhousing is 760$ overhere :-(

I've heard of it done, but you'd need to use '86-02 side housings unless you could accurately replicate the coolant seal grooves. You would need to replicate the oil O-ring grooves no matter what. But I see you already know that. https://www.nopistons.com/forums/pub...IR



I am interested to see how it turns out if you decide to try.

Im really interested in it as well, as I was just thinking about it a few days ago...

Apex seal support over the exhaust port?

Yes it will https://www.nopistons.com/forums/pub...IR#>/wacko.gif



Removing 5mm on each side ofcourse, not 10 on one side.



Haha everybody thought about this, but I was the only one desperate enough to ask the question https://www.nopistons.com/forums/pub...#>/biggrin.gif



Guess Ill give it a try.

yeah we thought about it too, see no reason it wont work...

Earlier this year I was selling an engine with 12A turbo rotor housings. Too bad. They only had 10k miles on a rebuild done in '03. The new onwer is a new member of the RX-7 club forum.



You can't get 12A turbo rotor housings anymore unless you buy them from MAXT. https://www.nopistons.com/forums/pub...IR#>/smile.gif

ive heard of filling in the o-ring groves with epoxy on the iron sides and it working ok, never tried it though

^^^ Huh

There are at least three things wrong with that.



First, the oil passage O-rings are in the rotorhousing on all engines, so even '86-02 side housings need the groove cut into the rotor housing. Mazda probably did this to keep this critical area of the side housings as strong as possible.



Second, we're taking 13B rotor housings and cutting them down. Even if they started out with coolant grooves, they would be eliminated by the machining process. We're not dealing with a two-groove problem, but a no-groove problem.



Third, there is no third.

Milling 13b housings down to 12a is common in Australia. Its a simple job with a cnc machine.

I'm currently using Series 5 13BT housings (turboII?) for my 12a. They are away getting machined down to 12A width. Not really common (although becoming more popular), but easily done. Mind you I'm also using the 13BT end housings so no water seal groove is advantageous for me.



Just do it and have the tooling path allow cutting through the chrome first then into the housing so you dont unpeal the chrome liner. If I had the gear I'd have done it myself.



Chris.

If you don't mind modifying an intake you could use all 13B irons with the grooves in them. Then no grooving of the housings would be required.



Lynn E. Hanover

I love modifying stuff, "unfortunately" I allready have done the grooving before, so the CNC program could be used again, just needs modifinationcating to do the oil/dowel o-ring.



Thanks anyway, mentor https://www.nopistons.com/forums/pub...#>/biggrin.gif

Yeah the number is still good on my 2006 epc catalog, so I can still get them.

That's good to know. https://www.nopistons.com/forums/pub...IR#>/smile.gif

https://www.nopistons.com/forums/pub...1047683771.gif



So I did it. It's possible.

FYI Rotorhousings are pretty hard on the millcutter bits, sure as hell not just regular aluminimums https://www.nopistons.com/forums/pub...IR#>/smile.gif





http://www.rx7club.com/showthread.php?t=696169



http://i23.tinypic.com/22f39z.jpg



http://i21.tinypic.com/11llkar.jpg



http://i24.tinypic.com/57k9j.jpg

Wow, that is one shiny housing.



I would guess the exhaust port sizes are different from 12A to 13B so will you be gaining much from the bigger ports on the 13B housings?

Nice job on the CNC!

you know what i was think would be cool. if you could do the grove on the rotor housing keep the one on the plate and instead of using silicone and teflon water seal using some sort of copper ring as the seal. so that you would never have a blown water seal again .think how good it would be...



what you guys think

Would be cool, but copper crushes and doesnt really spring back. So with expansion and contraction of the motor you would always have leaks.

yeah but you guys get my idea. it would need a little help to come to life .but when you think of the applications it would be awsome , then the only weak point would be the side seals. because the apex seal problem has already been addressed my rotary aviations

Read up a little on Banzai's nuclear o-ring coolant seal debacle to get your answer on why not



couple of links:



https://www.nopistons.com/forums/ind...howtopic=41442

https://www.nopistons.com/forums/ind...howtopic=44351

https://www.nopistons.com/forums/ind...howtopic=33607



Short story is coolant seals dont fail during normal use. They fail because something went wrong. You are better off spending the next to nothing available seals cost, and put the money towards actually fixing the problem, not trying to fix the symptoms.

No O-rings, just silicone.



Fill the cooling passages with concrete.



Drag only, of course, but then drag cars only need to run for a minute at a time tops.

Update, sort of...



http://www.rx7club.com/showthread.php?t=696169&page=2

If you look closely at the side of the rotor housing, you will see that the chrome insides are inserted into the aluminum housing, I have thought of this idea and it is impossible unless you create an insert yourself to exact mazda specs. I dont have the time and while thinking about it, you will spend more money through trial and error, instead of buying new ones.

Actually, the aluminum is cast around the steel inserts.