boost creeps

[jonsibal]

This topic came up when I was discussing turbo stuff with my mechanic, maybe yall can shade more light into this topic.

Besides the vacumm leaks and faulty wastegates, what other factors can cause boost creeps.

thanks

[BoostFed325]

can the tempature cause some boost creep? maybe the colder it gets.. im not really sure

[Mpowered02]

From my understanding, a wastegate or wastegate port that is too small for the engine displacement can be another cause of boost creep. I believe it's because as the RPM's rise and airflow through the engine goes up, the wastegate or port's airflow capacity is exceeded and can no longer vent enough of the exhaust gas away from the turbine resulting in additional, uncontrollable boost.
Why are you asking Jon? Have you been having problems with boost creep?

[whakiewes]

On higher boost cars, the Bypass/Blow-off valve can't support the amount of boost and you get boost creep. That is why Turbonetics created that like monster blow off valve with a 50 psi spring. I know that faulty intercoolers will as well. I reccomend pressure testing your intercooler every so ofter in you are pushing the limits of its flow rate.

Also, about the faulty wastegate. That is direct boost, and most tuners won't consider that creep, but moreless just a faulty wastegate. External wastegates usually solve all and any wastegate related boost creep problems.

One more thing a lot of people don't take into consideration is their boost controller. Many people don't research the differences between manual/electronic, single/dual solenoid, KPA/Bar/PSI, etc... Many people running manual boost controllers have creep from their units.

Wes

[e34biturbo]

Originally posted by jonsibal
This topic came up when I was discussing turbo stuff with my mechanic, maybe yall can shade more light into this topic.

Besides the vacumm leaks and faulty wastegates, what other factors can cause boost creeps.

thanks

to small a wastegate

[TheTruth]

Boost will creep when the wastegate cannot effectively bypass exhaust gases passed the turbine. It confused the hell out of me when BMW people were worried about boost creep on 8psi set-ups! Now I understand it though thanks to the forum!

[TheTruth]

Originally posted by whakiewes
On higher boost cars, the Bypass/Blow-off valve can't support the amount of boost and you get boost creep. That is why Turbonetics created that like monster blow off valve with a 50 psi spring. I know that faulty intercoolers will as well. I reccomend pressure testing your intercooler every so ofter in you are pushing the limits of its flow rate.
Wes

How is a faulty BOV, or no BOV at all, going to promote boost creep? If the BOV cannot support the PSI then it will just open under pressure but that will not cause creep just a boost leak. Just trying to understand this.

[Mpowered02]

Hmm...a faulty/too small BOV doesn't make sense to me either in terms of causing boost creep....unless you're talking about some of the older systems in which the BOV/bypass valve is the means used for controlling boost level. It seems that most designs now are using a wastegate of some sort for controlling boost, and a seperate blow off/bypass valve for releasing boost pressures when the throttle is shut (in order to prevent presures from backing up into the compressor and to keep compressor fan speeds up).

[dom]

Boost creeap ia caused by a waste gate being too small OR your piping. If you are venting it to atmosphere then it doesn't happen. When you vent it back to exhaust pipe, then it matters. How far the "dump" tube enters the exhaust path matters too, if it's too close to a turbine it can cause turbulence and some creep.

What is the actuator/spring rated at and how much boost are you trying to run. Maybe you're less then minimum?

[ICS Performance]

Mpowerd02 is correct a resrictive wastgate port. It must be an internal wastgate. Port out the exhaust door on the turbo, or get an external wastegate. Im have that problem on my STI it has a fpgreen turbo supports 1020cfm has a 15psi wastgate actuater on it, and it boosts up to 1.5-1.6 psi 22psi-23.52. Im having the same problem also. You can also get a blow of valve that is adjustable.You can get it to certain pressure, if it exeeds it it will blow it into the atmoshere or intake, depends on how you have it hooked up.

[Scho]

Does an open wastegate vented to atmosphere affect power / torque one is making??

[ICS Performance]

No not at all alot of race cars use that method. Its loud but you can put on a silencer.

[TheTruth]

Originally posted by Scho
Does an open wastegate vented to atmosphere affect power / torque one is making??

Yes, it does. The main benefit is a lot less backpressure.

[///3oris]

Originally posted by TheTruth
Yes, it does. The main benefit is a lot less backpressure.

In addition... it has a huge affect on torque and turbo spool. The best exhaust to use with a turbo system is: NONE. Turbo's like no backpressure.

On that note, Jon, what's your current setup in terms of turbine housing size, stage wheel, wastegate, and how it's routed? How much boost are you pushing?

Looks like time for a bigger wastegate or bigger piping. Did you by any chance recently change anything in your exhaust system (catless?) or has it always had the creep?

Boris

[BoostFed325]

can cold weather have an effect?

[BoostFed325]

can cold weather have an effect?

[///3oris]

Originally posted by BoostFed325
can cold weather have an effect?

Yes Think about it like this... an engine is a pump. How does it make more power? Put in more fuel. How do you make sure the fuel still ignites? (Keeping proper AFR) You add more air.

Cold = more dense = more air per stroke = more exhaust. Although heat expantion is important to a turbo's operation, the AMOUNT of air will also affect it to a great degree and has a huge impact on the boost curve.

Boris

[jonsibal]

Thanks for posting fellas.

Alvin and Boris, I posted this topic not because I was having problems with boost creeps, it was just a topic that came up one day.. sorry for not clarifying.

But as for my car, its still on jack stands getting worked on. My new turbo is just the 60-1 hybrid. Im installing an ext oil pump this week and the aquamist next week. Im hoping to start driving the car again very soon. Its been forever

Going back to topic, I also read that the placement of the valve unit of the electronic boost controllers can affect the responce and or cause boost creeps if the line(hose) used is more than 3 ft long from the valve unit to the top of the wastegate. Where did you guys placed yours?

Alvin, got your PM. Check yours

[TheTruth]

Originally posted by jonsibal
Thanks for posting fellas.

Going back to topic, I also read that the placement of the valve unit of the electronic boost controllers can affect the responce and or cause boost creeps if the line(hose) used is more than 3 ft long from the valve unit to the top of the wastegate. Where did you guys placed yours?

Yup, that's called boost spike as opposed to boost creep.

[BoostFed325]

thx ///3oris i thought the cold could do it but i wasnt sure.