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Old 03-28-2004, 03:11 PM   #126
afpdl
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The godspeed is ovalized a bit right by the turbo making it a slight bell mouth. But the plate infront of the wastegate is ground out its not flat like oem and the HKS just fyi.

BTW I have hit boost creep with my hks downpipe and stock catback. It has to be under 50 degrees though.
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Old 03-28-2004, 03:44 PM   #127
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Quote:
Originally posted by afpdl
The godspeed is ovalized a bit right by the turbo making it a slight bell mouth. But the plate infront of the wastegate is ground out its not flat like oem and the HKS just fyi.

BTW I have hit boost creep with my hks downpipe and stock catback. It has to be under 50 degrees though.
Thats what I have heard about the Godspeed DP.
Does anyone get boostcreep with the Godspeed DP?
I thought I saw somewhere in here that someone with a HKS had no boost creep but I guess I was wrong.

Dwight

Last edited by 2003 sedan; 03-28-2004 at 03:52 PM.
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Old 03-28-2004, 03:51 PM   #128
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I normally dont hit boost creep with the hks but I have 2wice for some reason. Its not really repeatable. Like I cant say its 40 degrees if I floor it in 4th it will hit, sometimes it does somtimes it doesnt.
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Old 03-29-2004, 01:19 AM   #129
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Ehh- With all this debate on which downpipes cause creep or not, everyone should be prepared to port the wastegate on an STi with any exhaust upgrage other than a catback. Results vary for many people depending on environmental variables and slight differences in the casting of their exhaust side.

I see no point in purchasing downpipes based on the fact that they do not give you boost creep. Better to spend your money on other mods, IMHO.
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Old 03-29-2004, 05:11 AM   #130
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Quote:
Originally posted by 2003 sedan
This is a TBE setup. No restrictions.
Flows mega-loads of exhaust.
I am not installing this for sound.
ok is it me or i dont think youre comprehending here. when you free up the exhaust, the turbo is allowed to spin up more efficiently and release more exhaust gas. this creates more boost pressure. this in turn creates more exhaust gas. this again creates more boost pressure etc. this would be fine if the stock wastegate hole was big enough to release the exhaust gas which keeps the boost at a stock level, but it's not, so the boost continues to rise and the ecu cuts fuel = BOOST CREEP. again, the wastegate hole cannot exit enough gas to keep the boost down.

sooo, whoever is designing this exhaust for you is claiming he can extract more gasses from the same wastegate port than others?

perhaps its a function of the turbo's efficiency. those who dont experience boostcreep are not flowing past the limit of the wastegate hole, so perhaps their turbo efficiency is lower somehow. what spools up turbos? exhaust heat. maybe their EGT's and downpipe are cooler, thus not spinning up the turbine despite having a 3" TBE?
no heatshield maybe?
lowered chassis = less airflow/lower pressure ratio below downpipe?
stock intake?
restricted intercooler?
hotter climate?

anywho, maybe someone can experiment and run an open downpipe and see if they get creep again? in theory it should happen again, unless a small section of the exhaust is needed to help maintain gas velocity..
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Old 03-29-2004, 06:07 AM   #131
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what spools up turbos? exhaust heat. , it`s still a little early here I`ve only had 1 cup of coffee . But I thought " engine exhaust" itself makes turbo`s spool up, not heat . Ok going for my second cup and my long 5 minute ride to work. Have a good day fella`s
-Dan
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Old 03-29-2004, 07:02 AM   #132
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[quote]Originally posted by XDEep
[
sooo, whoever is designing this exhaust for you is claiming he can extract more gasses from the same wastegate port than others?

No Claims by the manufacturer at all. No special design for me either.
There is someone in the "will a catback cause creep" thread that says he has a PDE DP & Injen catback with no creep. I havn't confirmed if he has had his wastegate ported.
The PDE & Godspeed DP look alot alike.
I am going to try this exhaust I have been talking about and will most likely get boost creep.
The wastegate will get ported after this.

Its a combination of heat and pressure that spools a Turbo.
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Old 03-29-2004, 07:44 AM   #133
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Quote:
Originally posted by 300blueballs
Ehh- With all this debate on which downpipes cause creep or not, everyone should be prepared to port the wastegate on an STi with any exhaust upgrage other than a catback. Results vary for many people depending on environmental variables and slight differences in the casting of their exhaust side.

I see no point in purchasing downpipes based on the fact that they do not give you boost creep. Better to spend your money on other mods, IMHO.
Right on, Man. I wonder if we should start a tally as to how many times this has to be explained, and then ignored....and then well explained again.... and ignored.... - ooooh! wait! I just got a vendor who has a pipe that will give me 400 extra hp and won't creep!!!!! (poop - there it goes again!)
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Old 03-29-2004, 08:03 AM   #134
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If you are all keeping up this thread then answer me on this:

Blitz SUS, VF39- Deadbolt PnP, stock ECU, Godspeed dp, Greddy Evo.

I'm hitting boost cut in 5th gear over 4000 rpm's. It does not creep in any other gear though I have not tried 6th over 4000 RPM's as I have a disdain for jail time and no track to test on.

Now what?
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Old 03-29-2004, 08:58 AM   #135
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im not too versed in thermo dynamics and what not, but ya remember hot gas expands and increases exhaust velocity (i.e. the idea behind exhaust thermal wrap), so it makes sense that it should spool turbos quicker. although you would like a larger pressure differential, i think insulating heat is more desired, so a coated downpipe/exhaust would be beneficial as well.

ya pretty, much. GIVE ME BOOSTCREEP! then i know we're getting somewhere so i can slap on a 42mm tial (ok, 38mm) and do it the right way. now where in the heck is a good sti tune?!

btw, how hard would it be to replace the flapper with a bigger one so you can port it more? if not, maybe you could weld some more area on it to increase the diameter. might be a bitch getting it flat tho.
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Old 03-29-2004, 06:14 PM   #136
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mmmmmmm-bigger flapper. WHY NOT?
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Old 03-29-2004, 08:26 PM   #137
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I had the "bigger flapper" discussion with a guy who is into Buicks, he wanted to know why we weren't doing it. He says he has a source for them and that it has been common practice I the Buick realm.

I have not been told by anyone that this exhaust system would be "creep free".
This was all me.
I had no intention of causing such a response.
I will most likely get boost creep.
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Old 03-29-2004, 10:35 PM   #138
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Quote:
Originally posted by lobelsteve
If you are all keeping up this thread then answer me on this:

Blitz SUS, VF39- Deadbolt PnP, stock ECU, Godspeed dp, Greddy Evo.

I'm hitting boost cut in 5th gear over 4000 rpm's. It does not creep in any other gear though I have not tried 6th over 4000 RPM's as I have a disdain for jail time and no track to test on.

Now what?
Maybe add a cat.
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Old 04-13-2004, 08:58 PM   #139
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I noticed the "Z1 Performance" suggested using a PE wastegate on the VF39 on this thread:

http://forums.nasioc.com/forums/show...ight=wastegate

Does anyone have any thoughts on this?
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Old 04-14-2004, 02:45 AM   #140
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An oversized wastegate flapper would only be beneficial if the turbo still encounters boost creep because of a complete porting and polishing of the exhaust.

All you need is a wastegate port to stop creep with the stock flapper, no need to upgrade.

It will be nice to source oversized flappers that fit for those who have gotten or want a complete exhaust side porting job.
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Old 04-14-2004, 09:48 AM   #141
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Quote:
Originally posted by 300blueballs
An oversized wastegate flapper would only be beneficial if the turbo still encounters boost creep because of a complete porting and polishing of the exhaust.

All you need is a wastegate port to stop creep with the stock flapper, no need to upgrade.

It will be nice to source oversized flappers that fit for those who have gotten or want a complete exhaust side porting job.
I've seen several reports of people still having issues with just a simple port (no PnP). There's even a guy local here in Florida that is having this issue.

I put together a poll, I'm curious on how this turns out:
http://forums.nasioc.com/forums/show...hreadid=540232
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Old 04-14-2004, 11:51 AM   #142
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So what is this PE wastegate- just a larger flapper?

What is stock flapper size?
I've seen PE advertise 34mm flappers for other apps.
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Old 04-14-2004, 12:28 PM   #143
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Quote:
Originally posted by lobelsteve
So what is this PE wastegate- just a larger flapper?

What is stock flapper size?
I've seen PE advertise 34mm flappers for other apps.
My undestanding is that it's just a larger flapper allowing you port the wastegate larger. I didn't look like the flapper could easily be replaced without some welding though but I'm not sure as I don't have on hand to examine. Does anyone have any information on these PE flappers? Any estimates on cost and what's involved to swap this out? The above thread seemed hint towards this be inexpensive.
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Old 04-18-2004, 11:04 PM   #144
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Ok.... I looked through this thread pretty intensely, and I didn't see any mention of this (sorry if I missed it):

Won't sticking with a divorced wastegate design dp help prevent boost creep? I know that Shiv's Stage 1 setup has a divorced wastegate, and I am getting ready to install a Stromung with a similar design.

In a perfect world, I would like to run Stromung's catless dp, highflow secondary pipe, and my custom catback straightpipe in STU class. Of course, I love my car and don't want anything to happen to it because of my own negligence. While I suppose that I'll never know til I give it a go, I'm really hoping that this divorced wastegate will help.


Thoughts?

- Miranda
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Old 04-18-2004, 11:20 PM   #145
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Quote:
Originally posted by Midnight_Gold
Ok.... I looked through this thread pretty intensely, and I didn't see any mention of this (sorry if I missed it):

Won't sticking with a divorced wastegate design dp help prevent boost creep? I know that Shiv's Stage 1 setup has a divorced wastegate, and I am getting ready to install a Stromung with a similar design.

In a perfect world, I would like to run Stromung's catless dp, highflow secondary pipe, and my custom catback straightpipe in STU class. Of course, I love my car and don't want anything to happen to it because of my own negligence. While I suppose that I'll never know til I give it a go, I'm really hoping that this divorced wastegate will help.


Thoughts?

- Miranda
This won't work. There's a member on here that has the Bosal divorced downpipe and was still experiencing the issue.
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Old 04-18-2004, 11:29 PM   #146
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Quote:
Originally posted by Midnight_Gold
Ok.... I looked through this thread pretty intensely, and I didn't see any mention of this (sorry if I missed it):

Won't sticking with a divorced wastegate design dp help prevent boost creep? I know that Shiv's Stage 1 setup has a divorced wastegate, and I am getting ready to install a Stromung with a similar design.

In a perfect world, I would like to run Stromung's catless dp, highflow secondary pipe, and my custom catback straightpipe in STU class. Of course, I love my car and don't want anything to happen to it because of my own negligence. While I suppose that I'll never know til I give it a go, I'm really hoping that this divorced wastegate will help.


Thoughts?

- Miranda
i believe a divorced wastegate exit's purpose is to prevent exhaust bypass from entering and disrupting the flow of the gas exiting the turbine. your exhaust may flow better but the wg port is still too small. there are people with the stromung divorced wastegate exit and still have creep (not yet ported).
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Old 04-19-2004, 11:14 AM   #147
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Then how does Shiv's system manage to eliminate boost creep, or does it?

- Miranda
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Old 04-19-2004, 11:49 AM   #148
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Quote:
Originally posted by Midnight_Gold
Then how does Shiv's system manage to eliminate boost creep, or does it?

- Miranda
It doesn't/can't.
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Old 04-19-2004, 01:54 PM   #149
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Ok, color me stupid, but everywhere I turn there's a different answer.

I would really love to learn a little more about the way my car works so I can be one of them smart car people.

I have been hearing a lot from some of the locals that even on an STi, stock boost plus single high flow cat wouldn't cause boost creep. Is it possible that the turbo creates enough of its own backpressure to eliminate the problem?

Please no flaming.. I am really trying to learn here.

- Miranda
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Old 04-19-2004, 02:03 PM   #150
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Quote:
Originally posted by Midnight_Gold
Ok, color me stupid, but everywhere I turn there's a different answer.

I would really love to learn a little more about the way my car works so I can be one of them smart car people.

I have been hearing a lot from some of the locals that even on an STi, stock boost plus single high flow cat wouldn't cause boost creep. Is it possible that the turbo creates enough of its own backpressure to eliminate the problem?

Please no flaming.. I am really trying to learn here.

- Miranda
The problem isn't back pressure before the turbo.

I just realized that the Vishnu downpipe retains the second OEM cat which would explain why you would be more likey to not have issues with boost creep.
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