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Boost Creep Fixed

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living-life

Probationary Member
3
0
Apr 4, 2004
Dayton, Ohio
I finally fixed my boost creep!! With EVO 16G 34 flapper, three inch downpipe (no cat), Apexi WS catback, and unported 2G o2 what ever I set MB (15 to 20 psi) at about 4500 it would shoot up however high I would let it. The first time I tried to eliminate boost creep I notched the wall on the turbo exhaust side outlet about 1 inch wide and ½ inch deep and opened up the o2 WG inlet and exhaust outlet, that held creep down too about 25-26 psi. The second time I opened up the inlet of the turbo housing so you could look down and see the WG inlet, (pic 001) Then on the exit side of the turbo exhaust I cut the notch about ¼ inch deeper than the first try and opened up the WG chamber a bit. (pic 002) On the o2 inlet I did a EVO gasket match and opened up both inlets quit a bit and cut a 1-inch wide by 3/8 inch deep notch between the two ports. (pic 003) The o2 outlet I opened up the WG outlet a lot mainly by remove the wall between the two ports, then opened up the exhaust outlet 2 ¼ inches. (pic 004) Got my creep down to about a one-pound with no drop at high rpm’s or WG blowing open. Would like to thank Craig at SBR for the advice and all the other articles written on how to solve this problem!! Thanks DSMTuners!
 

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It is unfortunate that you ruined your turbine housing in an attempt to get rid of boost creep. That was not necessary. A larger O2 housing would have done it, and without the need for any porting, no need for the notch in the housing (which works because it destroys turbine flow), and without the need for the larger flapper (which probably hurt more than it helped).
 
ShapeGSX I see your having trouble with boost creep.

Here’s statements you made in one of the Threads Started By: ShapeGSX First Evo III 16G in the 11s!
“On the 11 second pass, I had a 29psi spike with boost settling at 24psi. There is more boost init, but the spike gets too large.”
“I'm just looking at controlling boost differently to get rid of the 30psi spike.”
“While the tubular O2 housing eliminated boost creep, it also made the spike worse because the turbo spooled faster! So I put the ported stocker back on for now.”


You said it destroys turbine flow, didn’t you mean turbine efficiency?
Wouldn’t that mean it creates more backpressure? Didn’t you create
more back pressure when you removed the 2 1/2 inch tubular o2 and
reinstalled the 2G o2.
 
A boost spike is a very different issue from boost creep.

I solved my boost creep by installing a tubular 2.5" O2 housing with a 1 7/8" wastegate passage from www.122performance.com . But it made the spike worse. But I have done some work on my boost controller that should fix the spike (I hope). If it does, I may re-install the tubular O2 housing.

I think it is all a delicate balance. Screw with too much, and you either can't hold boost, or you creep, or you get a spike.
 
So a big O2 housing will eliminate boost creep. How do you explain alot of people having problems with boost creep on 3 inch O2 elim DP's????


An O2 housing is not the only way to elimate it. It will help but at somepoint it will make it worse. I did the same thing you did by removing the divider, but mine was on an old 14B. A bigger flapper, Wg hole, and a nicely ported exhaust housing is a very good method. The best is to go external but some of us dont have the coin to spend.


I will agree that it disrupts flow but for some it is a cheap and easily doable option that works.

Michael
:talon: :laser:
 
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