Here's the deal, have a street ported '90 Motor, everything is ported intake/center housing according to the racing beat templates. The problem is we can't port the exhaust with out getting TII rotor housings, which we really dont want to do. So my question is, how big of a deal will it be in terms of power loss, if everything is ported but the exhaust?

 

If you cut/grind out the exhaust diffusers you should be able to do some porting on the exhaust.

 

Has anyone actually tried this? I've heard it's super hard metal thats impossible to cut/grind. Any ideas on what I'd use to do this?

 

It's not too bad. I got a big chunk out of each housing with a regular old pair of snips. Leave the rest of the work to a grinder with a good carbide bit.

 

You might want to read the FAQ on porting on the MAZDATRIX webpage, they do not recommend removing the exhaust diffusers.

 

Yes that stuff does come out and it has been done before, a lot. Any ways ya i would not go to big on the exhaust cus you still want to be able to "push" it out the tail pipe. so not to big. clean it up and go mild on it.

CJG

 

Yes u should port the exhaust. Would u port the intake side of a head on a piston engine and not port the exhaust? That would defeat the purpose now wouldn't it.

 

The exhaust ports are actually more restrictive than the intake ports, believe it or not.

 

Yeah, I was looking at a 6 port rotor housing, and that port was very small.

 

Is your Rx3 a daily driver?? nice pics on your site..

 

What do you mean, are you saying you would not port it big, or are you saying when I grind the diffuser out, to not grind most of it out? Just grind the center part?

 

No
this is what i am saying. Grind all the diffuser out so that there is none of that left. Then i would go and only take the center of the port up about a 1/16 of an inch or so, not very much then take the sides out and up to almost match the top. do not make the upper corners square but tighten the radious's up and make the top of the port slightly curved. but widen it a little bit. Does that make sense? Cus if you go too big you run the possiblity of not being able to run a full exhaust system without problems.

CJG

 

Yes Judge, every day every where, and glad u liked my site.

 

I gotcha, your talking about the porting itself, I have the Racing Beat templates, so I'm not worried about that. What I'm worried about is getting this diffuser out, does anyone have any other suggestions on how to remove it? Or any real-life experiences they have had?

Thanks

 

i have never had to do it cus i stick to the old 4 port 13b's and 12a's and neither of those motors were cursed with them. I have seen a couple of the ones my friends did. My one friend said he justed ground it all out. So i think that is best best and posibly only option. He said it was a little time consuming but not to bad. If you just sit down and go at it, it shuold only take about an hour per housing if you have good bits and a good air die grinder. Both of the ones i saw had some of the material left in the botton where the diffuser was cast part of the whole insert. just cut the whole big thing off and smooth it into the bottom is my advice. it doesent have to be perfect, it just has to work. polishing an exhaust port does not do anything remember that.

CJG

 

THERE IS ANOTHER WAY!

You can remove the exhaust port sleeves and install the sleeves from Turbo II housings!

For my 91 NA engine bebuild, I removed the stainless steel port sleeves by removing the two dowel pins that hold the sleeves in place. (Use a drill press and drill them out) Then find two *garbage* rotor housings from a Turbo II. (Very easy to find on this list...) Remove the sleeves from the Turbo housings and install them into the NA housings. (Use set screws and locktight) Done. Then you can port the exhaust till your heart is content.

 

This is the exact thing I tried with a hand drill and snapped several bits, did you have a machine shop do it? And with what kind of bit? Dont have acess to a drill press, but I'm guessing a machine shop would.

This technique worked fine on the 86-88 housing, but doesn't seem to work on the 89-91 housing.

I had this same plan as I already have the TII sleeves.

Thanks for the advice