Is there a difference between the exhaust port location on the turbo and NA rotor housings? I have NA housings from an 86 13B (I have modified the sleeve to remove the diffuser and open it up to match the port) when I follow the racing beat street port template instructions the port opens very low, so low that it looks like it will end up in the water jacket if I grind out as far as the template shows. I will get pics up tomorrow to illustrate this better. Are the turbo housings different in this respect? I know I am lining the template up properly, I even called Racing Beat to confirm this.
Thanks

 

No man, the only important differences (I can think of) are the exhaust diffusers on the N/A ,and the coolant passage on the turbo housings... They're pretty much interchangable with no problems at all.

If you have the RB template, to get a 'rough' idea of where it should be, just line up the TOP of the open template with the TOP of the exhaust port... The RB template doesn't extend up at all IIRC, so this will pretty much show you where it needs to go (downwards etc.)...

Pics would really help.

 

This is a shot housing that I am just using for practice
http://www.rxbeetle.com/index.php?fu...e=P1010070.JPG
http://www.rxbeetle.com/index.php?fu...e=P1010071.JPG
BIG pics, too big to be attached

The line I made that indicates the bottom of the port is horizontal across the side. Should the port just be ground out at an angle to avoid breaking through into the water jacket?

 

I guess so.

I take it that's the "race" type exhaust port template?

If you're intent on using that design, I would do as you suggest and 'angle' down to the opening edge, trying to keep the angle as minimal as possible without porting through.

Are your exhaust diffusers removed?

 

that looks pretty interesting. i think i would tread very, very cautiously.

 

That is a "Street Port" template from RB (although I purchased it from Mazdatrix)


picture caption: This is just a shot of the GSLSE exhaust port with the street port
traced onto it. Refer to our Exhaust Porting FAQ for the details.

This is right from the Mazdatrix website. I have always heard to use the 70% rule for porting exhaust and that .080" lower (earlier opening) was sufficient for a street port) this template would make it open alot earlier.
I dunno, any one here used this template?

 

Oh yeah I did remove the whole sleeve to modify it.
I used a grinder to remove the material behind the roll pin so I could push the pins through.
Then filled the area I ground out (TIG welder)
I used a torch to remove the diffuser and smothed it all out with a die grinder.
I will be matching the sleeve shape to the housing port shape

 

If you go to Mazdatrix website, this link might help.

http://www.mazdatrix.com/faq/portexh.htm

 

How'd you get the difuser out?? I'm trying to do the same thing

 

Did you press the sleeve, or have to pound it out?

 

I'll get pics of of the process, If you have a die grinder its easy, the hard part is putting back what you ground out. Before figuring out my way i tried drilling the pins out (they are HARD I ruined a couple bits) I tried threading a sheetmetal screw in the pin to pull it out ( the pin just expands and grips harder)

I've been looking at the mazdatrix FAQ exhaust porting page, seems like that is there street port, I might go a litttle more conservative, just scoot the template up.
I don't want to kill my low end.

 

the nasty carboned up sleeve is one i just removed. You can see very well though where i ground out to allow the roll pin to be punched right out. The other Sleeve I have been playing with. It was an NA diffuser sleeve. I ground the sleeve removed the pins, filled the ground out area, welded more meat on the port facing edge and smoothed out some of the welding work with the grinder. You can see my nasty welding on the end of the sleeve, that material will be removed to match the port in the housing. I'll keep pics up as I go. I still don't really know what I am going to do about that template, just seems a bit much

 

Waidaminit. In that picture with the blue dye, it seems you have advanced the leading edge of the port. On the Mazdatrix site, they left the leading edge of the port, and expanded the trailing edge.

Yes, the more I look at it, the more it appears to be the case. Instead of advancing the exhaust port opening, Mazdatrix has just retarded the port closing. More duration without losing any degrees of your power stroke.

Is this not true?

I understand that you don't want the apex seal falling into the exhaust port, but why don't people make the exhaust port wider? Or at least smooth out the transition from case wall to port opening. I'm sure there is a reason. I just don't know what it is yet.

I mean, a full-width port, barring the the apex seal falling into it, would be nice for exhaust flow. Especially because it would also mean you could make the port of lesser duration and similar flow characteristics.

 

? you are loosing me smilodon the blue dye pic is right off the mazdatrix site.
http://www.mazdatrix.com/faqpics/porting/6pexh.jpg

where do you see them expanding the trailing edge on a 13B housing?