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Old 02-17-2004, 05:30 PM   #101
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hmm. I would only be using it above 60 degrees and up to 100 degrees.
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Old 02-26-2004, 01:42 AM   #102
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So the only way to fix the boost creep problem is to Port the stock wastegate?

Do STI's have boost creep and bad det stock?


ERIK
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Old 02-26-2004, 01:48 AM   #103
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It's not the only way but it is the easiest. You can also weld the internal wastegate shut and add an External wastegate.

People also use a boost controller but it does not remedy boost creep. It may keep it down slightly but it is not enough.

Stock STi's have no boost creep and no det. If you search the DET threads, you will find that Subaru remedied the problem for the few who had det issues and all STi's made now do not have that problem.
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Old 03-03-2004, 06:01 PM   #104
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Does the wastegate use a spring. I know on my other car to fix this problem we put a stronger spring in. I am sure it would take bit of testing to see which spring would be best but i could work.

What do u think?
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Old 03-03-2004, 06:08 PM   #105
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The problem is the hole isnt big enough with the wastegate fully open. So I dont see how changing the spring woudl solve anything.
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Old 03-03-2004, 06:18 PM   #106
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ah hah I see. But that would solve the Boost dying down before redline though
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Old 03-03-2004, 09:22 PM   #107
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Quote:
Originally posted by MAD TKD
ah hah I see. But that would solve the Boost dying down before redline though
The stock ECM wants the boost to taper at redline. I wouldn't change that without doing some serious monitoring.

-st
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Old 03-05-2004, 04:38 PM   #108
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Should I expect boost creep with Gt spec headers, uppipe, and down pipe?
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Old 03-05-2004, 07:21 PM   #109
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Yes.

Over warmer climates boost creep it is not as pronounced. The addition of an aftermarket downpipe will result in creep.
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Old 03-06-2004, 05:58 PM   #110
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well we did mine last nigth going to put it back today. i have the uppipe also from gt spec so we opened the entry to turbo a little bigger and ported teh wastegage. cant wait to hit the streetraces again lol
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Old 03-09-2004, 10:13 PM   #111
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Is it all downpipes ?? or just the over-efficient ones ? I recently purchased a Turbo XS turboback used for my STI installed it ran the car for a couple of days and finally drove it on the highway rolled into it in 4th gear at rather low rpm and gave it alot of load and there it was creep!! But on the other hand we installed a B&B turboback on another buddys STI, AND a Turbo XS manual boost contoller and we turned the boost up and he said his car didn`t creep at all , So I had to try it for myself , I drove it out on the highway in 4th gear again rolled into it gauge went up to 1 bar and stayed there "rocksolid" didn`t creep or bleed down at all , all the way to 7 thousand rpm , So then I tried it again this time in 5th gear and the same thing happened , the boost gauge shot up to 1 bar and stayed there, these next few time I couldn`t wind it all the way up to 7k rpm but more like 5 to 5.5 and still no creep , going back to the shop we took a good look at the exhaust systems and compared the two and the B&B just like the PERRIN down pipe has a dedicated wastegate dump tube that gradually tapers into the downpipe further down the pipe . Could it be that my Turbo XS downpipe / exhaust is too efficient ?? maybe flows too much exhaust, after all it is a 4 inch downpipe ?? Does anyone have a B&B turboback or a Perrin turboback and have boostcreep ?? I`m not trying to say that anyone`s exhaust is inferior , but the majority of threads that I have read has people running Turbo XS turboback having lots of trouble with boost creep . And I have one, and all but the boost creep issue I like my exhaust .
-Dan
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Old 03-09-2004, 11:03 PM   #112
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Quote:
Originally posted by manchvegasuruguayguy
Is it all downpipes ?? or just the over-efficient ones ? I recently purchased a Turbo XS turboback used for my STI installed it ran the car for a couple of days and finally drove it on the highway rolled into it in 4th gear at rather low rpm and gave it alot of load and there it was creep!! But on the other hand we installed a B&B turboback on another buddys STI, AND a Turbo XS manual boost contoller and we turned the boost up and he said his car didn`t creep at all , So I had to try it for myself , I drove it out on the highway in 4th gear again rolled into it gauge went up to 1 bar and stayed there "rocksolid" didn`t creep or bleed down at all , all the way to 7 thousand rpm , So then I tried it again this time in 5th gear and the same thing happened , the boost gauge shot up to 1 bar and stayed there, these next few time I couldn`t wind it all the way up to 7k rpm but more like 5 to 5.5 and still no creep , going back to the shop we took a good look at the exhaust systems and compared the two and the B&B just like the PERRIN down pipe has a dedicated wastegate dump tube that gradually tapers into the downpipe further down the pipe . Could it be that my Turbo XS downpipe / exhaust is too efficient ?? maybe flows too much exhaust, after all it is a 4 inch downpipe ?? Does anyone have a B&B turboback or a Perrin turboback and have boostcreep ?? I`m not trying to say that anyone`s exhaust is inferior , but the majority of threads that I have read has people running Turbo XS turboback having lots of trouble with boost creep . And I have one, and all but the boost creep issue I like my exhaust .
-Dan
i think you answered your own question. what are the differences between your cars- he has the boost controller and is holding steady at 1bar. above stock psi with a 3" is where the port seems to be restricting.
speaking of mbc's, i have no idea how one can physically LOWER boost, but i have heard people claim it.. somehow.. somewhere..
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Old 03-11-2004, 01:07 PM   #113
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thanks for the info I guessed right and just used a cat-back, not the TBE which was suggested. Boy that was close
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Old 03-16-2004, 12:39 AM   #114
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I will have to chime in here too. I just took my car for several runs: I have everything stock but I have removed only the stock muffler and placed a straight pipe instead, from the axle back.

The car "seems" a little quicker and I have not noticed ANY boost creeps whatsover. The boost will go all the way up to 1 bar and stay there...tried on 3rd, 4th and 5th....no problems.

The sound is freakin' great!
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Old 03-16-2004, 04:27 AM   #115
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Quote:
Originally posted by Z06-KILLR
I will have to chime in here too. I just took my car for several runs: I have everything stock but I have removed only the stock muffler and placed a straight pipe instead, from the axle back.

The car "seems" a little quicker and I have not noticed ANY boost creeps whatsover. The boost will go all the way up to 1 bar and stay there...tried on 3rd, 4th and 5th....no problems.

The sound is freakin' great!
i think the focus here is on the flow restriction at the wastegate by opening up the downpipe and on. your not having your muffler still leaves your stock downpipe to mid pipe with enough restriction to match the flow of the wg port.

think of it as blowing through a long narrow straw by making your lips open a little. cutting off most of it may help but still leaves the straw as a restriction. if your lips are the wastegate, changing the entire straw to a huge one now makes the size of your lips the restriction - you need to open them wider.
adding a section of small straw (up/down pipe/cat/muffler) anywhere along the big straw will make it match your lips again.
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Old 03-16-2004, 11:07 PM   #116
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Quote:
Originally posted by XDEep
changing the entire straw to a huge one now makes the size of your lips the restriction - you need to open them wider.
Hmm.... I tell my girlfriend the same thing
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Old 03-22-2004, 12:55 AM   #117
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I will be testing an exhaust in a few eeks that is a different design and may not cause boost creep. Although as I have read some cars do and some don't so my results will be my results. I am attempting this with a 3" catless TBE system. I will post the results either way after the install.
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Old 03-22-2004, 03:41 AM   #118
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Quote:
Originally posted by 2003 sedan
I will be testing an exhaust in a few eeks that is a different design and may not cause boost creep. Although as I have read some cars do and some don't so my results will be my results. I am attempting this with a 3" catless TBE system. I will post the results either way after the install.
but to not cause boost creep means this 3" catback is inefficient and not flowing what is should. why spend all that money to only limit yourself to that of the tiny wastegate port? if all you want is sound then just do a stock sized axle back.
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Old 03-22-2004, 08:41 PM   #119
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right! A good tbe causes creep. Bad ones restrict flow enough to prevent it. No magic bullet here
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Old 03-23-2004, 07:19 AM   #120
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Originally posted by Zornorph
right! A good tbe causes creep. Bad ones restrict flow enough to prevent it. No magic bullet here
Not necessarily. A bad downpipe design will not allow the wastegate to flow and cause creep. So it does have to do with design as well, it's not just about which has more restrictive cats, resonators, mufflers, etc.

-st
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Old 03-23-2004, 08:57 AM   #121
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you just said exactly the same thing that I did.
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Old 03-23-2004, 10:22 AM   #122
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Quote:
Originally posted by Zornorph
you just said exactly the same thing that I did.
You said:

Quote:

right! A good tbe causes creep. Bad ones restrict flow enough to prevent it. No magic bullet here
I read that as bad TBE restrict flow and PREVENT boost creep.

What I said is that a bad TBE can restrict flow out of the wastegate due to poor downpipe design and CAUSE boost creep.

-st
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Old 03-23-2004, 11:19 PM   #123
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right - either one. Stop up the wastegate flow or allow the main to flow better than the wastegate can keep up with.
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Old 03-28-2004, 10:09 AM   #124
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Quote:
Originally posted by XDEep
but to not cause boost creep means this 3" catback is inefficient and not flowing what is should. why spend all that money to only limit yourself to that of the tiny wastegate port? if all you want is sound then just do a stock sized axle back.
This is a TBE setup. No restrictions.
Flows mega-loads of exhaust.
I am not installing this for sound.
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Old 03-28-2004, 10:28 AM   #125
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Quote:
Originally posted by Zornorph
right - either one. Stop up the wastegate flow or allow the main to flow better than the wastegate can keep up with.
That is backwards.
If you stop up wastegate flow you will have boost creep.
If the turbine flows more than the wastegate is designed for you will have boost creep.
Tubine speed is caused by pressure differential and heat.
the only way to maintain this is by bleeding off gasses and heat (the wastegate).
If a bellmouth frees up flow across the board then one would assume that flow would increase across the board turbine and wastegate. We all know these downpipes cause creep.
But why not the HKS? or Godspeed?

Think about how the HKS downpipe causes the wastegate flow to hit a flat piece of metal and do a 90 deg turn then another.
This is contrary to what a bellmouth design does, it frees up wastegate flow.
From what I understand Godspeeds downpipe is an oval shaped pipe that allows wastegate flow to be partially blocked(maybe not).
If it is not partially blocked then why does this design not cause boost creep? Is it too restrictive? It is like a small bellmouth.
I think its do to some other reason maybe not. But I will know in a couple of weeks. And so will you guys.

Last edited by 2003 sedan; 03-28-2004 at 04:44 PM.
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