15 psi wastegate spring, but i boosted to 22psi

[hottscennessey]

okay guys, i need help with my boost creep. I have a 15 psi spring for my wastegate, its a SP61GT internal wastegate, and whenever i'm on it full throttle for awhile I'm having boost creep. I hate having to let off when I'm on it, just because somethings not working as it should. I just want to fix this. I have a 3" turbo back exhaust with a cooleze DP. Thanks guys.

 

[hottscennessey]

i read that boost leaks could cause boost creep.. how?

 

[clifftrail]

Are you sure your wastegate is opening?

 

[hottscennessey]

I dont know how i would check that, i assumed so because its brand new, but i dont know anything.

 

[PorterzSupra]

"full throttle for awhile"

If the wastegate was not opening at all it would be 22 PSI as soon as the turbo spooled up. Maybe its a poor vacume sorce? The wastegate could be undersized but since its internal I guess its made for your turbo? Are you using a boost controller? If it is pluged in backwards it will do that, or if your gonna run spring pressure 15 PSI dont use the BC at all or it will change even if its all the way turned out. In a hurry but all I can think of for right now.. good luck..

 

[clifftrail]

Did you just install the SP turbo? If so, did you shim the outer support arm on the turbo as it will hit the actuator hinge of the wastegate preventing it from opening smoothly causing a constant spike.

Look down the outside of the turbo where the support arm is and use a mirror to look a the hinge on the actuator to make sure there is not interference when it pulls open.

Does the turbo stop @ 22 or would it go higher if you kept going?

 

[hottscennessey]

I am running a boost controller, it did it when it wasnt installed too. I havnt looked at the arm and i will later tonight, and i belive it would keep creeping if i kept on it. I'll post back later tonight after work. Thanks guys.

 

[silvergsx623]

very possible the internal wg can't flow enoughto control the boost.

i have this problem on my eclipse. (on highboost) also i think if i ported my turbo eblow it would help the WG control the boost better

 

[hottscennessey]

very possible the internal wg can't flow enoughto control the boost.

i have this problem on my eclipse. (on highboost) also i think if i ported my turbo eblow it would help the WG control the boost better

I agree, thats the problem with a lot of the boost creep scenarios, but I bought this turbo with the internal wastegate, with a 15psi spring, I'll have to call SP and see if they've ever had problems with this before.

 

[hottscennessey]

okay, There is nothing near the wastegate actuator arm at all, but i did notice that the arm had a bolt on it, it is adjustable. If i played around with the actuator arm could that fix my problem?

 

[clifftrail]

Could, it should come preadjusted for 15 but it could happen. GL adjusting it on the car, hope you have small hands. You actually just loosen the bolt and then turn the arm clockwise/counterclockwise to adjust tension.

I doubt the problem is too small a wastegate. You've got the same turbo as the rest of us and yours would be a first for that.

Have you checked the vac source as Portez suggested to see if it's working properly? Take your elbow off and watch the w/g to see for yourself what it's doing. That is, if you can test it with the engine off.

 

[hottscennessey]

the vac source is good, it comes directly from the compressor housing.

The only way i know i can test the wastegate operation is rigging up a vac line from the wastegate actuator to an air compressor and watch.

I was thinking, if i had a boost leak then that would allow the boost to build and possibly escape from the leak, and keep the boost from going through the vac line to hit the acuator, this would leave the wastegate half-closed allowing the car to slowly build more boost. that seems kinda farfetched, but its possible? maybe?

 

[IJ.]

Pinhole in the actuator diaphram?

 

[hottscennessey]

I hope not IJ. Thanks for chiming in, I was hoping you'd share your knowledge on this subject.

 

[IJ.]

If you have access to a compressor adjust it's regulator to 10 psi and plug it into the actuator it should hold open with no escaping air noise.

 

[hottscennessey]

I'll try that first, it seems like an easy way to test the function of the actuator

 

[CPT Furious]

I have the SP61GT with the internal wastegate and it holds the 15 psi with my BC turned off just fine. Don't think it's a lack of wastegate performance.

 

[hottscennessey]

yea, thats what i'm saying, i've never heard of this problem once. What could it be, because the only thing i can think of is a boost leak (if that even makes sense), or some other problem like IJ was saying.

 

[Jspec7m88]

A little late into the convo, but I've never paid attention nor had to deal with the scenario of "boost creep". Can someone tell me the basic idea of what happens during Boost Creep?

 

[IJ.]

You have a 10 psi spring in the gate but at high rpm/load you see 12 psi or higher.

this is creep

Happens sometimes if the gate can't flow enough to keep the shaft speed under control.

If you've shimmed the WG it can happen when the spring coilbinds and can't let the flapper open far enough.