Hey, I have 2 Tial 35mm wastegates on my turbo manifold that dump to the air. I have always had slight problems. First I had 15psi springs in them but they wouldn't open until 17.5 psi. They did hold boost at a steady rate though. Then I put 8psi springs in them and they would open at 10.5 psi. They would also hold this boost level at no problem. This all took place this summer.

Now fast forward to now....
I have never ran my car in the cold weather and I am getting crazy boost creep. If I shut my boost controller up and run off of just the wastegate springs, I will hit 10.5psi and hear the wastegates open like normal. Then as the RPMs rise so does the boost. Before I can even reach redline I am hitting 20 or so psi. I even saw the needle climb to 23psi once. Whenever this happens I lift the throttle quickly. Also I am running methanol injection. So normally I would baby the car until the weather gets warmer but here is my problem. I am getting tuned in Feb. by Steve Kan and I am going to creep cause the weather will still be too cold.

So which fix would be better?
1) Have my manifold modified so it would hold one larger wastegate? (Also how big of a wastegate would I need?) Ex. HKS 60mm???

2) Have my wastegate flanges cut off of the manifold and have 2 larger wastegates put on? (Also what size) Ex. 2 Tial 44mm???

Please let me know ASAP because I leave for school in a couple of days.....
Thanks,
Phil

 

If your going to tune inside the ambient temp will be in the 60s! Did you have creep when driveing in 60 deg spring or fall? I run a single hks 50 but i dont have the same turbo and it doesent creep. But it did on the tial 38. Any way i know there is better advice from someone out there!!

 

Phil,
Do you have dump tubes off of your gates? You may want to change to softer springs. Mine was doing the same thing on the dyno. Ray Wilson @ PFS said that I needed a softer spring in my gate(single 44mm).

Dee Edmundson

 

i had an hks 38 and it was not even close to sufficient. i had terrible creep, switched to tial 44 and i was still getting creep in this cold midwest weather until i removed the dump tube. with the dump tube off my boost stays right where i set it with spring or boost controller. so if you have dump tubes you might want to take them off until it warms back up.

 

I run two separate 35 mm gates , one one each turbo ...... no problems at all , infact when they open my boost drops from 10.5 to about 9.5 psi. Boost creep can be caused by bad placement of the gates , one of mine is placed on the "apex" of the first bend as it comes out the motor , where I thing velocity would be very high , if you look through from the motor flange its a straight shot , the exhaust gas doesn't have to turn , one of the hardest things to do is to get the exh. gas molecules to make a turn (it doesnt want too!) the other on the front rotor is also placed on an "apex" but on the second bend after the motor , and similarly when the gate opens the exh. gas stream would easily split into a "Y" flow (I think !) with some going out the gate and some out the turbo. If you do not place them correctly , you would need a large gate to get the job done.

 

I’m running a single Tial 46 mm and don’t have any issues keeping the boost down to 10 psi, I run it now @ 22, but what your experiencing seems weird.
One would think with (2) 35mm gates the volumetric efficiency should be higher than a single 46mm. With one gate on each tube the efficiency should be pretty damn high, even if placement is slightly off. Making exhaust gas go is a different direction is hard.

Can you test the Wg’s individually? One of the diaphrams’ may have a leak causing only one to operate properly, you should only need to give them a positive pressure from a compressor @ only 10 -11 psi to see the valve open and close. This can be done on the car still without having to remove them, you may want to have a helper so you can be under the car and watch the operation of them. I pinched mine one time when switching from a 10 psi spring to 1 bar. Didn’t realize it till I was getting 16.5 psi with the 1 bar and was getting steady 10 with the 10psi spring.

If they both work fine testing them with compressed pressure, check your boost control system, all the lines into them a pin hole or leak somewhere may be your culprit.

I would have pointed the finger towards your boost controller, but your getting creep even with it off. And having had the system work previously would lead me to a failure in part of the system rather than poor system design. The design may just be responsible for the increase of 1-2 psi over the springs. Long story short even though you hear them opening, they both may not be opening, or only partially opening. or only 1 opening

Also which boost gauge are you pulling #’s from.

 

Re-read your post a few times, if everything checks out WG, and line wise take the boost control actuator out and just run manifold pressure to the WG, take all possible failure points out of the system b4 you start cutting and welding

What boost controller are you using?

 

Good advice.

Pdviper, do you have a quite large and free flowing exhaust system?
What the turbine housing a/r? Could be to small..

 

I have a 4" full exhaust, no restrictions......
My A/R is 1.15.

I dont know what to do, I leave for school tomorrow and have not fixed this yet!!!

 

Did you try any of what I posted? The more I though about it, it’s not the design of the system because it worked before. There’s a failure somewhere in the boost control system.

Trouble shoot the Boost control system piece by piece. Shouldn’t take you more than an hr to do if you take your time.

 

Agreed, good luck Phil. I hope you get it straightened out.

Dee Edmundson

 

I would move up to a 1.32 Housing.

Wastegates are not meant to be used to compensate for too small of a turbine housing.

 

I have a 4" downpipe and exhaust and 1.15 A/R, I have the same issue with a Tial 44mm wastegate with only a 10 lbs spring, I start off at 10 lbs then by 7K its already around 20 lbs. I am tuned for all the way to 30, so its not a big deal. I have a greddy type S boost controller, but its only when its cold winter temps, not summer temps. Just the free flowing setup and not enough wastegate is my deal. I need to step up to a 50 or 60mm. A 1.32 A/R will only increase the exhaust flow up top and cause more of a boost creep at those high rpms because his turbo can def support it, and will cause a slower spool initially, which also , your bridge port might also be contributing up top for the creep.

 

I feel like a freak with my tiny T04S.

Very weird how in the colder months you get more boost. It defies logic, but then again the HP# we all made defies most logic.

With winter air being colder and denser I could see some increase, but 10psi over a warm day is weird. And since he’s running dual 35mm’s and one on each runner, his effective WG is even larger.

 

Well, I just hooked up a compressor and test each wastegate with the car running. You can hear them both open onn their own. I guess that means that they both work and I guess the problem is Purely the cold air.....????

 

I guess it could be, although I can’t under stand how a pressure system could be affected by the cold. I mean I understand the air’s denser, so the compressors moving more molecules of air @ the same volume, and sure theirs more going into the combustion chamber, and that will produce more exhaust, but to be out performing WG’s by 10 psi seems abnormal.

If you dumb it down it even makes less sense, valve opens @ 10 psi and vents off xxx volume of air per min,
Now some how in the cold even though we know theres a bit more air packed into that same volume, how the gate that should still flow xxx cfm now is being out performed by 2 fold and boost is going double of what the valve could originally vent off.

Maybe it is in-efficient design and its just really showing its flaws in the cold? But if that were the case how come this isn’t the problem for everyone.

Free flowing exhaust will be the same, and in the winter by theory since the exterior of the pipe will be cooler then in the summer, thus slowing down the exhaust gas by cooling it, one would thing it would negate any issues of the free flowing 4 in exhaust.
But if one looks @ this to be the culprit, vehicles with open DP’s should never be able to control boost. Air will take the path of least resistance. But with exhaust gas will play into the flow dynamics of the manifold, which in the winter or summer is still 1,000 degrees…..so the temperature of the manifold and wg shouldn’t be to far off from a cool summer day.

So with all that typing im still back at sq 1.

If both WG’s are operating properly and all the lines to them from the boost controller are right, could the cold some how be affecting the Stepper motor in it? But under the hood after it warms up should be relative to a cool summer day once she’s cooking..

None of it makes any sense, final part of the conspiracy theory, could the boost controller only be partially opening the WG’s in this magical cold air? try it with the stepper motor bypassed and just run manifold pressure to the WG and see whaen they open, if they still open and you get creep your just plain SOL LOL


OHH i just re read your post, you "heard" them open, they may not have opend all the way i know its a long shot but as you cas see i find it hard to believe your out performing 70 mm of WG.
Seeing is believing, but who knows maybe im off my rocker on this one. we really need one of the big boys to chime in

Don’t know if any of the above makes any sense or just makes me look like a retart who drank to much coffee this afternoon

 

I still get some creep in the summer months, but not near extra boost in the cold cold weather. You might have something going with the solenoid idea Bacon...and you are right....if he runs straight vaccum and using the spring tension only, then either he is outflowing the wg's or his setup is too efficient, haha.

 

I run a full 4 inch exhaust with a 1.0 hotside and a tial 44mm wg. today making some 2nd gear pulls with the boost controller off, the boost stayed right at the spring pressure, 12 psi. This was in 60 degree weather. About a week ago in 45 degree weather I was seeing 15 psi under the same circumstances, although I never revved the car to redline.

 

i would get 2-3 psi higher on cold mornings, did u always have this wastegate set up?

 

Yes