insane boost creep>>i cant stop it! help!

[A2TDI]

setup

built aba bottomend (2008cc)
20v head ported with all springs, retainers and ferrea valves, and QED purple cams
turbo: HX40 with BEP .70 ar ex housing
precision 46mm wastegate (18 lb spring)
CTS cast 4 into 1 t3 exhaust manifold

this thing creeps like a MOFO! it spikes to 25 lbs instantly then raises to 35psi before 7000rpm and there is no boost controller and i have changed the boost source from being in the manifold to right at the compressor. I want to eventually have the car tuned at 30 psi but right now if i keep my foot into it it doesnt ever seem to stop climbing in boost. I had a tial 38mm gate on it and it was creep so i said hey ill buy a new much larger gate and my problems will be solved! I was wrong... A couple things i didnt mention is its running on 94 octane, water meth and the engine endures the constant strain of a built 3 spd auto..

[GinsterMan98]

Where is the WG placement on the manifold?

[VRT]

Wastegate is too to big. Creeping from there

[tasty danish]

Wastegate is too to big. Creeping from there

whatever dude. What does that even mean?

It has to be some kind of wastegate issue. Either your placement (manifold design) sucks or it isn't passing air somehow. 46mm should be large enough to not creep like that unless it isn't opening for some reason.

[TBT-Syncro]

i'd start by replacing the vac/signal line to the wastegate.
verify the dump tube isnt bent/collapsed/crushed/etc

since those are two things that have stayed constant even with the wastegate change.

[.therealvrt]

The dump tube diameter should not be smaller than the wastegate opening.
Probably not the issue but it would be good to change unless the tube was bigger than 46mm to start

[AJmustDIE]

Wastegate too big? LOL.

Seems like you would know how to run the lines because of the engine specs alone, but do you have the reference line on the right port? Someone has to ask lol.

[GinsterMan98]

Wastegate too big? LOL.

Seems like you would know how to run the lines because of the engine specs alone, but do you have the reference line on the right port? Someone has to ask lol.

Oh yeah, forgot about that on, lol.

[A2TDI]

i have tried changing the vac\boost line to several diff locations including right onto the compressor housing. I am not running a dump tube right now just to put that out of the equation. I am thinking its the manifold design.. im thinking about changing back to the hx35 to see if the creep continues. I think maybe the engine flows so much more with the larger turbo that its out flowing the manifolds port to the wastegate. I want to port it to see if it makes a difference but the casting is fairly decent and somewhat thin and i am convinced it wont help.

manifold in question.

http://www.ectuning.gr/site/EShop/Pr...4-fcc229db1c95

[GinsterMan98]

That has good port location. Like said above, which port are you running the boost signal to on the WG?

[TBT-Syncro]

but you have the signal line going to the correct port on the wastegate? (basic, but not so uncommon)

[dslazin]

take an airline to the waste gate and see if it is getting stuck?

[A2TDI]

boost line running to the bottom port on the wastegate. and i had the car running and hooked an air line up to the boost hose and when i pushed air in the gate opened and the car got louder. Im very baffled right now....

[sp_golf]

take an airline to the waste gate and see if it is getting stuck?

x2 make sure it's opening all the way. I'm guessing you can hear it open on the car?

[V-dubbulyuh]

If that wastegate has a total of (3) THREE ports (two on the base and one on the top), make SURE that the second signal port on the side is capped off or you will blow that motor up. You should only be utilizing two of the ports, ie top for vac, one of the side ports for signal.

Just a precaution but you were having the same issue even when using the Tial 38mm so your problem with creep is somewhere else.

[B4S]

Is the wastegate plumbed back, or just open to atmo without a pipe?

[A2TDI]

its open to atmosphere and the lines are hooked up correctly and the second bottom port is blocked off. so i wonder what my other problem would be..when i had the hx35 on and the tial 38mm everything was fine and dandy! as soon as i put the hx40 on it was uncontrolable so i figured i would throw a larger wastegate on to cure it...that didnt happen...the engine is built for that boost and i want to run 30 psi but its hard to tune something that just keep climbing....i know it isnt right and i want to fix it.

[V-dubbulyuh]

If the spool of the turbo is overwhelming your manifold/wastegate setup it will creep/spike as you stated. You stated that your only change was the HX35 to HX40 when you first noticed the spike problems. You changed the wastegate and saw no improvement. On very fast spooling turbos sometimes the wastegate can not open rapidly enough to vent the boost causing a spike. When I have had that happen before I have had to relocate the wastegate closer to the collector. Not saying that this definitely is your problem but at least something to think about.

[xtremvw3]

Deff check you capped a lower side port, then remove WG and make sure you put the sealing Ring, then if you open the WG to change spring re open and check diaphram for rips. Good luck.

we have ran that manifold before at 26psi rock steady, not the dump tube, not the deisgn, not the set up. Re check the WG

[GTijoejoe]

Deff check you capped a lower side port, then remove WG and make sure you put the sealing Ring, then if you open the WG to change spring re open and check diaphram for rips. Good luck.

we have ran that manifold before at 26psi rock steady, not the dump tube, not the deisgn, not the set up. Re check the WG

That is the right thing to do, look at the WG which probably is the problem. Do you have any smaller springs?

Its best to try and tackle this issue with a smaller spring, because if you can't fix it by running less boost, it wont be fixed... and its the safer approach to fixing your issue.

[Grahams81]

Just had a look at the manifold, it states it's for 38-39mm waste gates - how are you using a 46mm wastegate ???

What is the diameter of the wastegate hole in the manifold at the wastegate flange ?

If your using a 2 bolt 38mm wastegate to 46mm convertor then it'll probably flow no more than the 38mm one with the smallest size being the bottle neck.

[tasty danish]

Its best to try and tackle this issue with a smaller spring, because if you can't fix it by running less boost, it wont be fixed... and its the safer approach to fixing your issue.

Less boost will exacerbate the problem. I don't know what you're trying to suggest. The more boost he runs, the less will flow will need to be vented by the WG so it'll have an easier time.

If you're really stumped you might even try removing the WG to see what your boost does. Or running it without the spring.

Say for instance you remove the wastegate, drive the car, whatever boost you wind up spooliing is the minimum your wastegate port can possilby flow. Maybe add the WG without a spring next, to see how much a fully open WG can flow.

[GTijoejoe]

Less boost will exacerbate the problem. I don't know what you're trying to suggest. The more boost he runs, the less will flow will need to be vented by the WG so it'll have an easier time.

If you're really stumped you might even try removing the WG to see what your boost does. Or running it without the spring.

Say for instance you remove the wastegate, drive the car, whatever boost you wind up spooliing is the minimum your wastegate port can possilby flow. Maybe add the WG without a spring next, to see how much a fully open WG can flow.

That's exactly my point.... He should be able to run low boost period, its a lot safer to fix a boost creap problem at 10psi than it is at 25 which he is currently at. As well as actually fixing the problem 100% at low boost is best, not just making it easier to fix the problem but actually fixing the problem. There is no reason why he shouldn't be able to run 8-10psi on his setup... something is seriously wrong.

[A2TDI]

i ported the outlet of the wastegate to 46mm and welded on the v band flange. I wanted to port the whole thing but i didnt think it would make too much difference. I have been thinking about cutting off the wastegate elbow and porting it out so i could fit a 90 degree stainless tube that would be the same inner diameter as my wastegate and weld it all up. what do you think?

[tasty danish]

That's exactly my point.... He should be able to run low boost period, its a lot safer to fix a boost creap problem at 10psi than it is at 25 which he is currently at. As well as actually fixing the problem 100% at low boost is best, not just making it easier to fix the problem but actually fixing the problem. There is no reason why he shouldn't be able to run 8-10psi on his setup... something is seriously wrong.

yes I agree he should be able to control the boost, however, it is more work for a wastegate to hold 8 psi, than 25. If he is getting creep at 25, he would get it, and more dramatic, at 8, though terminal boost would be the same regardless.

[TBT-Syncro]

i think i said this already. but just hook an air line up to the wastegate signal line, and see what happens.

[GTijoejoe]

yes I agree he should be able to control the boost, however, it is more work for a wastegate to hold 8 psi, than 25. If he is getting creep at 25, he would get it, and more dramatic, at 8, though terminal boost would be the same regardless.

I'm more than well aware how wastegates work. The point is he doesn't have some huge engine. with a 38mm gate he should be able to run 6psi of boost no matter what. he has a 46mm gate... he has a boost creep issue regardless of what pressure it doesn't even matter, there is no argument that he should fix the problem and be able to fix it at low boost, therefore never having a high boost concern.... so you might as well fix it at low boost. If you mean terminal boost (over all 25-30psi) will be the same regardless of the spring...you actually don't know that, that is just your feeling because you actually don't know what is wrong with the system.... Smaller spring the gate will open sooner, will the gate open the same amount with a lower spring than higher spring.. maybe but who knows.... fact. lower is safer regardless if it gives you the same outcome, its not even a discussion.

i think i said this already. but just hook an air line up to the wastegate signal line, and see what happens.

... no you never said that
You should really bench test the valve

[tasty danish]

I'm more than well aware how wastegates work. The point is he doesn't have some huge engine. with a 38mm gate he should be able to run 6psi of boost no matter what. he has a 46mm gate... he has a boost creep issue regardless of what pressure it doesn't even matter, there is no argument that he should fix the problem and be able to fix it at low boost, therefore never having a high boost concern.... so you might as well fix it at low boost. If you mean terminal boost (over all 25-30psi) will be the same regardless of the spring...you actually don't know that, that is just your feeling because you actually don't know what is wrong with the system.... Smaller spring the gate will open sooner, will the gate open the same amount with a lower spring than higher spring.. maybe but who knows.... fact. lower is safer regardless if it gives you the same outcome, its not even a discussion.



... no you never said that
You should really bench test the valve

You're misunderstanding me, but really we are saying the same thing. I responded to you in the beginning just for posterity's sake. It is a common misconception that you need a larger WG for more boost. Your original comment seemed to be playing into this. Perhaps I was mistaken.

Though I do take issue with 1 thing you said:

will the gate open the same amount with a lower spring than higher spring.. maybe but who knows

I know. The spring only controls when it opens, a fully open gate is an open gate. So if he always creeps to a max of 25psi, he will hit that regardless of spring. Though I agree low boost is safer, and if you can control it down low, it'll be cake when turned up.

[GTijoejoe]

Then we're on to the same thing.... either way, we need a valve inspection.