2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

Boost Creep Fix

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Old Aug 27, 2006 | 10:29 PM
  #1  
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Boost Creep Fix

Ok guys, this does take some work but it actually results in NO BOOST CREEEP!!!

I've done this on two FC's and both have the same results. With the boost controller turned off, the car maintains stock boost without creeping. Here's what I did.

1. I pulled off the backing plate / flange on the back of the turbo (after pulling off the downpipe just 2 13mm bolts are holding it on).

2. Disconnect the wastegate actuator from the wastegate door so the door can swing freely.

3. This works better with the turbo out of the car, but you need to note where the wastegate door hits the backing plate. When you find it, grind the hell out of that spot on the plate and on the wastegate door. I put a spot of black RTV on the spot i suspected the door was contacting the plate and when it appeared on the plate, just ground it down. I didn't go more than 1/2 was through the plate, but here are the results.

I've got a few picts of how far the door opens before and after. You can see the locations I ground in order to get the door to open further.

The first car I did this to has been running with no issues for the last year. The second car was just purchased and this was a precautionary measure I implemented after the rebuild.

http://tooyoungto.servebeer.com/images/turbogrind
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Old Aug 27, 2006 | 10:33 PM
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well if you need to pull the turbo to do this right, why not just port the wastegate and eliminate boost creep that way?
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Old Aug 27, 2006 | 10:35 PM
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I wasnt gonna say it..
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Old Aug 27, 2006 | 10:52 PM
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Originally Posted by arghx
well if you need to pull the turbo to do this right, why not just port the wastegate and eliminate boost creep that way?
+1
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Old Aug 27, 2006 | 10:56 PM
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plus this has been tested and proven to be false. it is solely dependent on the mods to the car and the turbo.


i'll bet you pinks if i just backcut where you said it on my hybrid Turbonetics S4 turbo with a stock sized wastegate it would spike to 20+ til the turbo blew to bits or the motor whichever first..

you need to state mods to be clear or someone may try this thinking they are safe and BOOM! you have one pissed off forum member chasing your *** around...
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Old Aug 27, 2006 | 11:21 PM
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amg you lose today
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Old Aug 28, 2006 | 12:37 AM
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I'll agree with Dr. Ifter that cutting out the back-plate helps. I've done it twice (although also doing heavy WG porting), and I think it makes sense. Not only that, it takes about 3 minutes and it definitely doesn't hurt.

Here's what I did:



But I also did this (with a heavy "back-cut"):

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Old Aug 28, 2006 | 12:40 AM
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BTW, *gasp*... Do you have Infini wheels? Your FC is sick.
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Old Aug 28, 2006 | 12:40 AM
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amg! stock flapper!

how is it doing creep wise?

edit: love the broken stud btw.
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Old Aug 28, 2006 | 12:56 AM
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ahhh...
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Old Aug 28, 2006 | 12:59 AM
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answer the question n00ber!

i am always curious how other people's porting turned out with the stock flapper, i only got about 1-2psi of creep with my .60A/R Turbonetics hybrid with the stock flapper ported as large as i could manage it.
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Old Aug 28, 2006 | 01:07 AM
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LOL, I sold that turbo, but was able to keep it around 9psi with N/A rotors, street-port, 3" TID, 80mm full exhaust etc.

Screw a new flapper for the stock turbo... Some people just don't know how to do a good WG port.
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Old Aug 28, 2006 | 01:08 AM
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heh
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Old Aug 28, 2006 | 06:52 AM
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Anybody who's tested the wastegate actuator with compressed air knows that grinding back the backplate does virtually nothing, because it's the stroke of the actuator that limits how far the wastegate flap can open. The flap does normally hit the backplate, but it can only travel ~1mm further before the wastegate actuator spring is fully compressed. That tiny bit of extra travel will barely improve wastegate flow, if at all.
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Old Aug 28, 2006 | 03:45 PM
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From: Tacoma WA
My mod list:

HKS full turbo back (dual system) 3" split to (2) 2.5"
S5 Turbo (stock with backing plate mod)
FMIC
HKS AIC with 2 400cc injectors
HKS EVC III set to 12psi
Intake with stock TID

Reminder: Even with the boost controller off, I don't creep at all.


As for pulling off the turbo to do this right, for those of you that look at the pics, you can see where the plate was cut and duplicate the cutting in the similar area on your plate.
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Old Aug 28, 2006 | 04:15 PM
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Originally Posted by Dr. IfTeR
S5 Turbo
No WONDER it worked, the S5 wastegate shouldn't need much help to work properly.....telling it "naughty wastegate" sternly a few times is usually enough to stop boost creep on an S5.

Its the S4 guys who really need to worry about creep.
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Old Aug 28, 2006 | 04:16 PM
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The wheels are BBS RS.
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Old Aug 29, 2006 | 12:46 AM
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Originally Posted by classicauto
No WONDER it worked, the S5 wastegate shouldn't need much help to work properly.....telling it "naughty wastegate" sternly a few times is usually enough to stop boost creep on an S5.

Its the S4 guys who really need to worry about creep.
whurd.
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Old Aug 29, 2006 | 12:47 AM
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Originally Posted by NZConvertible
Anybody who's tested the wastegate actuator with compressed air knows that grinding back the backplate does virtually nothing, because it's the stroke of the actuator that limits how far the wastegate flap can open. The flap does normally hit the backplate, but it can only travel ~1mm further before the wastegate actuator spring is fully compressed. That tiny bit of extra travel will barely improve wastegate flow, if at all.
I love you NZ...
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Old Aug 29, 2006 | 05:04 AM
  #20  
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I'm a boost creep...
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Feel the luurv...

S5 turbo + stock TID = good boost control. I doubt the modified backplate is having any effect.
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