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Removing sleeve defusers. (pix)

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Old 02-19-08, 11:59 PM
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Removing sleeve defusers. (pix)

Can you guy tell me if the sleeve ok to use. because of the small gap. I dont know if its true but some have ran without sleeves entirely.
Old 02-19-08, 11:59 PM
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Old 02-20-08, 12:24 AM
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Yea you can run it without the "diffusers" in. I had new TII housings ported by Mazdatrix and I'm not sure if the TII housings originally don't have those or if they ground them off but my current setup has no "diffusers" or whatever they're called. The tech at Mazdatrix told me that all it's for is to help dampen the exhaust pulses.
Old 02-20-08, 12:36 AM
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The turbo 13B housings did not come with sleeves that had diffusers. The NA's did. I have heard that removing the diffusers on a basically stock NA setup will wreck your exhaust flow, even worse if you just pull the sleeves entirely. Apparently it would still run, but you'd be better off leaving it alone or doing a full port job of some sort as opposed to only changing that detail about the exhaust ports. But that's just what I've heard. Search, I know it's been covered before.
Old 02-20-08, 04:07 AM
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Why are you doing that? The Mazda engineers had a reason to design it that way.
NA with and TII without.
If you're looking at improving flow, port the damn thing.
Old 02-20-08, 08:46 AM
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Yes, the training manual shows why they're there (see sig. below).

Unless you're porting the exhaust (along with intake), keep the diffusers. Usually one uses either TII rotor housings, grinds the diffusers off, or takes out the insert and puts a TII insert (a thread on how to do this is in the archives).
Old 02-20-08, 08:51 AM
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The gap is fine. It's a small disruption to flow, and will eventually erode away, but you'll never notice.

In a non ported NA application it's best to keep the diffusers as it controls the noise.
Old 02-20-08, 12:06 PM
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What do you mean erode away? You mean get pluged with carbon? The diffuser is there to reduce the noise and it reduces the flow. im taking it out because im going turbo. That small gap on the botom wories me about heat cycle essue. Is it true that some have ran without SLEEVE AT ALL??? What is the reason for those 2 small vaginas on the sides?
Old 02-20-08, 12:15 PM
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Lol, you see? You need to give people more info to go on! E didnt know you were going to go turbo! IF you are, summing up all the stuff above, grind the things all the way off, or replace em with the turbo sleeves. From what I researched, it is not recomended to run with no sleeves, shure people have done it, but...

Can you not cut off the rest of that and make it flush? OR better yet, get some templates, and port the thing?
Old 02-20-08, 12:23 PM
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im shooting for 250 hp at the wheels, i dont think it needs porting, i ported my intakes, minor port job.
Old 02-20-08, 12:48 PM
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From what i read on here it impossible to hit 250 in a na
Old 02-20-08, 01:48 PM
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250 at the wheels, impossible without P-Porting it.
Old 02-20-08, 02:09 PM
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you should port the exhaust big time and 250 hp??? what setup do you have ?
Old 02-20-08, 02:15 PM
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He's going turbo (post #8).
Old 02-20-08, 05:39 PM
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turbo turbo turbo

That lil space on the bottom in the pic (between sleeve and aluminum) its ok? i dont want to have heat damage because of that.
Old 02-20-08, 06:30 PM
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Originally Posted by rx7vadim
What do you mean erode away? You mean get pluged with carbon?
No, I mean that it will erode away. Hot exhaust gasses will hit the sharp edge and eventually the metal will begin disappearing. Not a big deal though.

The diffuser is there to reduce the noise and it reduces the flow.
The diffuser has virtually no effect on flow. This has been tested on the flow bench and dyno.

im taking it out because im going turbo. That small gap on the botom wories me about heat cycle essue. Is it true that some have ran without SLEEVE AT ALL??? What is the reason for those 2 small vaginas on the sides?
Don't worry about the small gap. Also don't run without the diffusers. Port velocity goes into the toilet and a lot more heat will be transferred to the cooling system.

I'm not sure what "vagina" you are referring to.
Old 02-20-08, 06:45 PM
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Your best bet, short of making your own sleeves, using TII rotor housings or swapping in TII sleeves, would have been to remove the N/A sleeves and perform the following:
- Cut the front of the Diffuser flap off so it is flush with the rest of the sleeve.
- cut out the two "wings" of the diffuser
- put two notches on either side of the diffuser "ramp"
- use an arbor/hydraulic press and a torch (if required) and press the "ramp" completely flat to match up with the bottom of the sleeve.
- grind down the rest of the diffuser so it is completely flat
- Use a Stainless filler rod and TIG the two Ramp notches closed.
- TIG the two holes at the top of the sleeve closed, with stainless round.
- reinstall, port as desired.

There are some situations where removing the sleeve completely IS beneficial, but a turbo/street ported N/A engine are NOT this sistuation.
Old 02-20-08, 06:47 PM
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Originally Posted by Aaron Cake
I'm not sure what "vagina" you are referring to.
For the life of me, I can't picture two vagina's in any form in the stock, or modified, exhaust sleeve.

Makes me wonder if the poster has actually seen a vagina...
Old 02-20-08, 07:05 PM
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no never seen it. its 2 holes on the sides.
Old 02-20-08, 07:09 PM
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Those two holes in the sleeve are for the fresh air feed from the air pump directly into the exhaust stream. I like to TIG them closed.
Old 02-20-08, 07:41 PM
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Atleast do it nicely and take out the sleeved first!!







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