Worse Creep WITH 34mm flapper than without

[super95awd]

Ok, 34mm flapper is installed (mind you the o2 sensor housing is ported to 2.5" on the dp side and gasket matched on the turbine side), took it out for a test drive. It creeped far worse than it did before (yes I ported the hell outta the wastegate hole). So I was like, "Hmmmm that's strange." So then I turned off my Profec-B to see how it would fair running off just the wastegate spring. Same results. Hits maybe 14 psi, holds for a second, then begins to rocket to like 22-23. Not good. I went back home to fool around with the wastegate, making sure it was opening properly and such. Seemed to be opening fine. I'm completely stumped. Any ideas guys?

 

[1fast97gsx]

mine did that too ... I had the manifold ported and no creep whatsoever

 

[super95awd]

My manifold and turbine inlet are ported to 7cm. Tomorrow I'm gonna try to run a line straight from the pressure source to the actuator and bypass the Profec-B. I hope it works like that.

 

[1fast97gsx]

I have an hks evc4 and it was giving me problems too at first. We hooked up a manual boost controller and it was all good. I ended up resetting the ecu and reprogramming the controller and its been fine ever since.

 

[Enraged78]

Remove the divider between the wastegate flapper and the exhaust turbine housing. If you look at some of the new design turbos by IHI, they already have the entire divider removed. This allows the air bouncing off of the flapper (it never opens up all the way, it's more like 50 degrees open) a straight path to the exhaust. If you have the divider as-is, the air will head straight into a wall, and have to push it's way back up. All that resistance make it easier to just spin the exhaust turbine. I have the 34mm flapper, and the wastegate hole hogged out to about 29mm, and I still get creep up to 16PSI with my 3" turboback AND a cat. If I had the divider removed, I would have no creep. Luckily, my boost is set to 17PSI, so I don't see the creep anymore, but if I knew a few months ago what I know now, I would have hogged the hell out of that divider.

Matt.

 

[Keaka26]

sounds to me like you are having a problem with your exhaust setup, super95awd... 3" downpipe, 3" testpipe, and a 3" catback? Yeah, that sounds like its your problem. Try stepping down to a 2.5" mandrel d/p...Either that, or move to an external gate. You could also try a tubular o2 housing either with or without an external dump, that would probably help/solve your problem...

Let us know.

 

[super95awd]

I'm almost sure there has to be a problem other than 3" exhaust. I never creeped with a cat and I knew I would with a test pipe but not this much. I'm gonna work on it some more and see if I can figure it out.

 

[Keaka26]

you said it right there. It never creeped with a cat. Meaning the cat was providing sufficient backpressure to prevent the boost creeping.

The reason you get boost creep is because the exhaust gasses have super low resistance through the turbine , when the wastegate passage opens up, the exhaust still choses the path of least resistance and chooses the turbine and boost will continue to CREEP ...If the backpressure in the turbine is sufficent, the exhaust will look for a better way out, which is the wastegate. Why dont you try a 3" high flow cat...

 

[super95awd]

I had a 3" high flow, but I just don't know if I wanna give up the power of the test pipe. Would a tubular o2 sensor housing stop it, or just help?

 

[Keaka26]

for some, it stops it, and for some it only helps. I think a tubular o2 with an external dump would probably solve your problem if you dont want to give up that test pipe... (which i can understand)

 

[super95awd]

Just worried about it being obnoxiously loud eventhough its only at full boost. I might like it, I might not. What about a 3" o2 housing with the WG routed back in?

 

[Keaka26]

there are tradeoffs to everything. With the wastegate routed back to the exhaust, you get rid of the noise, but you also lose some of the possibility that your boost creep issue will go away. Maybe you can buy the tubular o2 housing with the gate routed to the exhaust, and if that doesnt work, maybe you could modify the gate and make into an external dump.

Another alternative might be to get the external dump version, and extend the dump pipe all the way underneath your car... I have heard this helps with the noise.

 

[kpt4321]

Something is wrong with your setup, probably the EBC or the wastegate. It should not have gotten worse, there is no reason for it.

Run a line right from a pressure source to the WGA, and see what happens.

Manifold porting does nothing for creep.


....Kyle T.

 

[super95awd]

Yes, I know manifold porting does absolutely nothing for creep. I have already ran my compressor to the actuator and it opens perfectly fine. I bypassed the boost controller too, as I stated before, and that's not the problem either.

 

[Ben K]

Just because you ported the wg passage in the turbine housing doesn't mean that it was ported properly to eliminate creep. Don't mess around with porting your manifold, it will not help your creep problem. Don't get an externally dumped o2 housing, it will not help your creep problem. Don't remove the divider on the outlet of the turbine housing, it will not help your creep problem.

I will guarantee that if you create a good step to separate the incomming exhaust gasses between the turbine and the wastegate passage, your problem will be fixed. I am certain there are some pics floating around the net that show what I am describing.

 

[Keaka26]

Originally posted by Ben K
Just because you ported the wg passage in the turbine housing doesn't mean that it was ported properly to eliminate creep. Don't mess around with porting your manifold, it will not help your creep problem. Don't get an externally dumped o2 housing, it will not help your creep problem. Don't remove the divider on the outlet of the turbine housing, it will not help your creep problem.

I will guarantee that if you create a good step to separate the incomming exhaust gasses between the turbine and the wastegate passage, your problem will be fixed. I am certain there are some pics floating around the net that show what I am describing.

While I definitely respect AGP turbo, and their abilities and the fact that they know their stuff, I have to disagree (and correct me if im wrong).

How would putting a tubular o2 with an external dump not help/solve boost creep? What other purpose for them IS there? An external o2 dump would drastically relieve pressure in the wastegate port, thus allowing the exhaust gasses to be released through the gate rather than building more boost in the turbine....I dont see how this could not work.

 

[super95awd]

Originally posted by Ben K
I will guarantee that if you create a good step to separate the incomming exhaust gasses between the turbine and the wastegate passage, your problem will be fixed. I am certain there are some pics floating around the net that show what I am describing.

Well since I'm not exactly sure what this "step" is that you are talking about, could you please grab me a pic of what you're trying to explain? I was also about to open up the hole where the WG passage dumps back into the main exhaust passage in the o2 housing. It's widened some but I figure I could get it larger.

*EDIT*

Is this kind of what you're trying to explain?

You must be logged in to view this image or video.

 

[mitsugsx95]

" (mind you the o2 sensor housing is ported to 2.5" on the dp side and gasket matched on the turbine side)"

First of all, that doesnt do anything to cure boost creep if its only ported on the DP side. You have to make sure that the wg passage on the other end of the o2 housing is ported... well hell, just remove the whole divider on the o2.

"Remove the divider between the wastegate flapper and the exhaust turbine housing."

and more .

Thats exactly how to get rid of it. You could have a 5" exhaust and it still wouldnt creep.

 

[super95awd]

If you would reread what you quoted, the turbine side of the o2 housing is gasket matched, and internally where the wg passage dumps back into the turbine passage, its opened up consiberably. And about removing the divider, I'll believe AGP .

 

[mitsugsx95]

Well Mr. Smarty pants. You can gasket match all you want, but you still wont have enough flow out of the wg area to keep up with the boost thats being built up (hence the creep). Do what you want, but if you want it done right the first time, do as others suggest.

 

[super95awd]

Finally its fixed. I took off the o2 housing and ported the living hell out of the wastegate passage. I followed this up with pulling the turbine housing, grinding behind the wg arm for it to open farther, and creating a lip in the turbine inlet for more exhaust gasses to be diverted into the wg (just like AGP said). Went out and tested it. Held 0.8 bar all the way to redline with the wg spring being the form of boost control. (for all you PSI folks that is approximately 11.5 psi)

 

[Keaka26]

good to hear, and it saved you from buying more stuff...even though having a nice tubular o2 housing would have been cool too

 

[Sotarts]

Big circle: deviding step removed on the outlet side of turbine housing.

Small circle: some of the inside wall removed to make more space for the flapper arm to open more.

I have a hard time trusting that though.

I personally would buy an o2 sensor housing (stainless steel custom) that has no devider at all.