so i'm planning on getting a full turboback exhaust but my friend tells me, "what about boost creep?" and then i answer that i'm getting a boost controller to keep the boost down since i'm running on 91 pump gas. he replies, talking about my wastegate being damaged or something.
anyone have any issues with boost creep and screwing up your engine? i still don't fully understand boost creep, so please explain that too. thanks.

 

i am no expert but boost creep is bascially once the car has reached its max boost and the rpms of the car continually increase the boost will continue to climb beyond your max boost setting. It may not happen in every gear but maybe 5th the majoroty of the time. It would be more noticable on a very cool night when the car is making more power.

 

Boost creep is rising boost due to not enough exhaust bypassing the housing. For example, you're set for 13 psi, and when you floor it, you get a quick rise to 13 or 14 psi. But then as rpm's climb, the boost creeps higher and higher: 14, 15, 16, 17, etc. Enlargening the wastegate hole is one cure for boost creep, as you did.

Spiking is when your wastegate hole is large enough, but your actuator can is taking too long to fill with compressed air, so you *temporarily* overshoot your boost level. Example: you're set for 13 psi, and when you floor it it quickly rises to 16 psi, but then gradually drops downward towards 13 psi again.

A common problem with modded engines is a combination of spiking AND boost creep. That's where you're set for 13 psi, and when you floor if it overshoots to 16 psi, *begins* to drop back down, but as the rpm's rise it goes up again!

* Normal boost rise when set to 13 psi = shoots up to 14, then 13, 13, 13...
* Spiking = shoots up to 16, then 15, 14, 13, 13, 13...
* Boost creep = shoots up to 14, then 13, 13, 14, 15, 16, 17...
* Spiking and boost creep = shoots up to 16, then 15, 14, 13, 14, 15, 16,17...

Set a manual boost control to 11 psi and floor it slowly in high gear. It should go to 11 psi and hold it pretty well. If it starts to slowly climb over 11 psi as the rpm's get high, that's "creeping". The boost creeps higher at high rpm's because there's too much exhaust flow for the wastegate hole to bypass.

Now go to 11 psi again, but tromp on it quickly! It will shoot to 13, or 14, or 15 psi, then drop down to 11 and stay there. That's "spiking".

Spiking is a quick flash of high boost that goes a little beyond your set boost point. If you are set for 11 psi, and you tromp on it quickly, this might happen: boost "spikes" to 14, quickly drops to 11, then slowly "creeps" back to 14 or more as the rpm's climb. Now you are seeing spiking followed by creeping!

 

Buschur racing boost controller is $75 bucks and hallmans are only like 100. You might aswell just get one to be safe, its not like they are expensive or anything. Very easy install aswell. Oh, and yes I noticed my boost creep up once I installed a turboback, but I ordered both the MBC and exhaust at the same time.

 

Boost creep has nothing to do with a boost controller! You could buy a $10,000 boost controller and not fix boost creep! Boost creep is a mechanical/fluid dynamics problem. Boost creep only occurs when not enough exhaust gas is being bipassed by the wastegate. This happens even if the waste gate is FULLY OPEN, and still can not flow enough. So by freeing up the exhaust gases after the turbo with the Turbo-back exhaust he is planning, the exhaust will move more freely through the turbo, creating quicker and easier boost. If the the waste gate is not sized correctly for the free flowing exhast....YES, boost creep can occur as the wastegate can no longer dump any more exhast gas away from the turbine, and results in the boost increasing and increase as the problem compounds. will this happen.... not sure, it all depends on how much wastegate flow you have in reserve on the stock housing.

 

Hmm, thank you for correcting me Guess I was wrong...

 

you guys avatar is confusing me. Looked like you were talking to youself for a bit.

I get a 1.5 psi up but I think it really depends on your mod.

Usually happens to people with a full back exhaust or bigger turbo from what I've noticed.

 

the evo doesnt really have any boost creep problems...the wastegate is very well

design and can flow a good amount of exhuast gas...the sti on the other hand has

boost creep probs do to the wastegate being to small...and port job would take

care of the creep...from the mods u want to do..u should not have nay probs w.

creep...gl

 

Exactly. Boost creep has not been an issue with the Evo. Moving to Evo tech forum.

Speedlimit...

 

thanks. my friend who told me about the problem does, in fact, own a sti. haha.

 

okay can someone explain boost spike because I've been spiking a lot after the clutch install. Turn boost down on the MBC and still the spikes. My car have also lost a lot of power on the top end. NOt sure if ECU is pulling timing because of the spike or not. BR S4 with turbo xs RFL BOV and dynoflash. Not sure if the cold weather is part of the problem. I suspect boost or exhaust leak.

 

boost spiking... man this is scaring me... so now the question is... whether MBC fixes boost creep or not right? Anyone?

 

I think that I am experiencing something similar with my 03 Evo. I live in Chicago and since the cooldown in weather I noticed that during very cold days after I start the car and let it run at idle for 5-7 minutes and then take it on the road I get higher boost than normal if I really step on it. I have a Blitz DTT with a built in boost guage and I just recently recorded a boost peak of 1.41 hkpa(I think this might be 20 or 20.5 PSI)l I usually record a peak of 1.31 or 1.32 hkpa, but lately I noticed 1.37hkpa or 1.41 hkpa. I do not have any mods other than the ones listed on my signature. Any thoughts?....I am planning to get a APS turboback exhaust soon...should I be concerned of boost creep?

 

Boost creep and boost spikes are not the same. You need to understand the difference before installing an MBC. And a MBC will not prevent boost creep or boost spike. Type in boost creep in google .... then boost spike. Everything is there.

Speedlimit...

 

Thanks!