So the minimum boost on my car with a MHI Evo III 16g w/tubular O2 housing and external 38mm MVS WG was 20-23PSI. Waste gate spring is only 14.5psi. The rest was all creep.

I had already ported the waste gate passage some when I went external, so I don't know what the original as cast port size was, but best I could measure it was 29mm after I had done a little to it. Well removed it today and did this.




Now best I can measure it's 31.5-32mm. That's like a 10% increase? Think it's enough? I don't want to do this again, but I don't want to go to crazy on it either. The goal is just to be able to turn the boost down to 15-16psi as a minimum.

As measured by a powder scale, I removed about 93grains, or 6 grams of material.

Ideally you want to remove the "lip" where the center ring goes in the housing. It looks like you still have a little bit of a lip.

Id port the housing more. Helping the turbo breathe will also reduce pressure.

I just re read your post and saw your running external. Id port that hole a lot bigger.

Like this bro.

I wasn't nearly as concerned with the volute as the waste gate port. All I'm working with at home is a carbide bur and Dremel tool. At work I have air tools I could use, I'll take it with me to work. How far should I go with the waste gate passage? I thought getting crazy and opening it up until that "pipe" extention / waste gate passage wall is removed would be bad for flow, since it points the exhaust athe the waste gate valve.

ETA: that picture makes the step for the fire ring in the volute look worse than it is.

not sure if these help...

http://www.dsmtuners.com/threads/how-to-cure-boost-creep-by-porting.186525/

http://www.dsmtuners.com/threads/oldman-could-you-grade-my-porting.275021/

Current progress.

should be enough for the turbine inlet part, as the evo3 turbine housing is thinner than the 1Gs...

Well I didn't port it enough... still creeping. Just not to 24psi, only 20psi now. Ugh...Oh and I hit a deer test driving it.

RipperXX said:

Well I didn't port it enough... still creeping. Just not to 24psi, only 20psi now. Ugh...Oh and I hit a deer test driving it.

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Man talk about horrible luck!! How much damage was done to your car?

Near as I can tell, not that bad. I think I have located someone with the parts I need, as soon as he sends me pictures of the actual parts I'll be buying them. What concerns me is the pop up on the passanger side looks like it was pushed back? the gap behind it to the hood is next to nill. So, something is bent there, pop up still works fine but when in the down position isn't sitting right.

Not really eager to dig into it right now until tax return. Then I'll patch it up, touch up the paint that chipped off the bumper cover, and get the FMIC setup squared away. Then if it's going to creep to 20psi anyway, then I mid as well just set it there :/

RipperXX said:

Near as I can tell, not that bad. I think I have located someone with the parts I need, as soon as he sends me pictures of the actual parts I'll be buying them. What concerns me is the pop up on the passanger side looks like it was pushed back? the gap behind it to the hood is next to nill. So, something is bent there, pop up still works fine but when in the down position isn't sitting right.

Not really eager to dig into it right now until tax return. Then I'll patch it up, touch up the paint that chipped off the bumper cover, and get the FMIC setup squared away. Then if it's going to creep to 20psi anyway, then I mid as well just set it there :/

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Doesn't sound to bad could have been a whole lot worse!

Did the headlight bucket it's self get bent from the impact?

black91awdturbo said:

Doesn't sound to bad could have been a whole lot worse!

Did the headlight bucket it's self get bent from the impact?

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No idea yet. I parked it in the shop and haven't set foot in there since other than to put away some tools.



When my tax return comes in, i'll probably set aside $1500 or so for the upgrades and repairs. Until then, just going to leave her where she's sitting.

Quick, what's the threading for the manifold to turbine bolts? M10x1.5?

All I can say is don't over-polish things. There is a threshold before porting/polishing too much will decrease performance. No point of going into fluid dynamics but in general it's best to just take away the surface roughness but still have some degree of it left.

M10 1.25

Kryndon said:

All I can say is don't over-polish things. There is a threshold before porting/polishing too much will decrease performance. No point of going into fluid dynamics but in general it's best to just take away the surface roughness but still have some degree of it left.

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I seem to remember reading something about a slightly rougher surface causing a layering effect that's more beneficial than a perfectly slick surface.

Used 80 grit flapper wheels followed by 120, nor going higher than that. Wish I had taken a picture of it before hand from last time. Anyway here it is as it sits now.



I needed to k ow the threading due to two of the bolts losing several of there threads on the way out.. 3rd time they have been used. So I was going to replace them anyway but shit was that scary touch and go getting them out afraid I was going to snap one in half. The bolts that lost their threads are still in the turbines threaded holes, so got to chase them clean. Thing is they came out fine. Then I put two back just to hold things while I disconnected the coolant and oil lines, went to take them back and and about 3/4 turn into it they started getting tighter...which is when I started praying and being very careful and patient.

This being the 3rd time, I'm getting quite sick of this. I just want to be able to set it to 21psi and it run straight to it and stop. (For daily). Previously I would have the waste gate open at 14psi and it would creep to 21, open at 15psi creep to 22-23.

Note, camera makes it look like the lip foe the fire ring is still somewhat there, it is but just barely. It actually recesses ever so slightly there, I'm not touching the top lip/flange.

What is the rest of your exhaust system like? Are you still running the stock downpipe and catalytic converter? Exhaust restrictions after the O2 housing can also effect boost creep.

I had a terrible time controlling boost creep looks like wastegate hole is fine but your inlet still has a long way to go. Port until the lip is completely gone just keep an eye out on how thick the material is because I whent threw it one time but just welded it up. My set up is 3 inch straight pipe with 38mm external wastegate and I can hold 6 psi to redline. Post pictures when your done

This port work should eliminate the creep for u. I never had spiking issues when set at 15-18. Have u tested your wastegate?

SOADweskey said:

What is the rest of your exhaust system like? Are you still running the stock downpipe and catalytic converter? Exhaust restrictions after the O2 housing can also effect boost creep.

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This. With the external and porting you've done, you shouldn't have problems holding a lower pressure unless your exhaust is corked up somewhere.

I see you have a 3.25 ally exhaust, whatsbthe downpipe/cat section looking like?

SOADweskey said:

What is the rest of your exhaust system like? Are you still running the stock downpipe and catalytic converter? Exhaust restrictions after the O2 housing can also effect boost creep.

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Tubular O2 housing with external Tial MVS 38mm waste gate dumped to atmosphere
Megance Racing downpipe connected to custom (made by me) 3 1/4" aluminum exhaust, no CAT or anything. There is one fairly sharp turn since I didn't follow the normal exhaust path most vendor units follow where they turn before the rear diff, mine turns just after between the diff and rear fuel tank. But I was under the understanding that something like a CAT would cause more back pressure and thus prevent creep as the free'er flowing path is then the atmospheric dumped waste gate.

gst-turbo said:

I had a terrible time controlling boost creep looks like wastegate hole is fine but your inlet still has a long way to go. Port until the lip is completely gone just keep an eye out on how thick the material is because I when threw it one time but just welded it up. My set up is 3 inch straight pipe with 38mm external wastegate and I can hold 6 psi to redline. Post pictures when your done

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Do you have a picture to post? That's exactly what I'm worried about, getting so thin that it cracks or something.

I don't have pictures but I followd this link and you really need to remove the lip and port to 7cm gasket match. How is your exhoust manifold is it ported because if it not ported to match 7cm the flow dosent help the external wastegate. http://www.dsmtuners.com/threads/how-to-cure-boost-creep-by-porting.186525/

gst-turbo said:

I don't have pictures but I followd this link and you really need to remove the lip and port to 7cm gasket match. How is your exhoust manifold is it ported because if it not ported to match 7cm the flow dosent help the external wastegate. http://www.dsmtuners.com/threads/how-to-cure-boost-creep-by-porting.186525/

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I have the evo III exhaust manifold which flows like a well ported 2g manifold. I don't intend to port it at this time.

Well took a little more out of it.
Here you can see the lip like I said us basically gone,
BUT looking down the volute you can see it looks like it's still there. That's due to the slight recess I mentioned.

Final shot sitting in the back of the Honda waiting to go home.

If it creeps after this...i dino. I'll check into the waste gate I guess? I clearly hear it open at 14-15psi though, has a 1 bar spring.