Wastegate Creep
May 6, 2009, 08:42 AM
#1
Wastegate Creep
So I just watched the video EvoDom posted about Wastegates from GCG.
Yea, I'm not the smartest man out there when it comes to turbos, and found that vid pretty interesting.
My question is about wastegate creep that happens on internal wastegates. Since I have a o2 dump, I know when the wastegate opens up. That is around 15psi. I'm tuned for 25 psi. What confuses me is why is the wastegate opening up so much earlier? Is it because if it opened later the car would probably over boost? Or is there another explination.
Thanks for any info.
Yea, I'm not the smartest man out there when it comes to turbos, and found that vid pretty interesting.
My question is about wastegate creep that happens on internal wastegates. Since I have a o2 dump, I know when the wastegate opens up. That is around 15psi. I'm tuned for 25 psi. What confuses me is why is the wastegate opening up so much earlier? Is it because if it opened later the car would probably over boost? Or is there another explination.
Thanks for any info.
May 6, 2009, 09:14 AM
#4
Registered User
not sure what ur asking in a nutshell:
the WGA is connected to a flap that opens to regulate boost. the WGA is wired to the boost controller. the stock WGA opens @ 12 psi, but the boost controller will control when the WGA sees the 12 psi thus opening it.
so, at ur full boost, 25 psi, the boost controller will let air flow to the WGA, opening it so the boost cannot cross that amount.
the WGA is connected to a flap that opens to regulate boost. the WGA is wired to the boost controller. the stock WGA opens @ 12 psi, but the boost controller will control when the WGA sees the 12 psi thus opening it.
so, at ur full boost, 25 psi, the boost controller will let air flow to the WGA, opening it so the boost cannot cross that amount.
Last edited by rolly1818; May 6, 2009 at 09:17 AM.
May 6, 2009, 09:29 AM
#5
not sure what ur asking in a nutshell:
the WGA is connected to a flap that opens to regulate boost. the WGA is wired to the boost controller. the stock WGA opens @ 12 psi, but the boost controller will control when the WGA sees the 12 psi thus opening it.
so, at ur full boost, 25 psi, the boost controller will let air flow to the WGA, opening it so the boost cannot cross that amount.
the WGA is connected to a flap that opens to regulate boost. the WGA is wired to the boost controller. the stock WGA opens @ 12 psi, but the boost controller will control when the WGA sees the 12 psi thus opening it.
so, at ur full boost, 25 psi, the boost controller will let air flow to the WGA, opening it so the boost cannot cross that amount.
Or at least in my case it does. Like I said, my car is set to boost at 25 psi, but I hear the o2 dump at around 15psi and up. Isn't that considered WG creep?
May 6, 2009, 09:35 AM
#8
^^^ What Rolly said.
But if everything is working fine and you still have boost creep, then it is mostly likely caused by the o2 housing. If the wastegate side is too small to allow enough bypassed exhaust to escape, then the surplus exhaust pressure will spin the turbo wheel causing boost to rise.
Also this is not just for internal wastegate systems. It can also happen to external dumps as well.
But if everything is working fine and you still have boost creep, then it is mostly likely caused by the o2 housing. If the wastegate side is too small to allow enough bypassed exhaust to escape, then the surplus exhaust pressure will spin the turbo wheel causing boost to rise.
Also this is not just for internal wastegate systems. It can also happen to external dumps as well.
May 6, 2009, 11:08 AM
#13
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Since I have a o2 dump, I know when the wastegate opens up. That is around 15psi. I'm tuned for 25 psi. What confuses me is why is the wastegate opening up so much earlier? Is it because if it opened later the car would probably over boost? Or is there another explination.
May 6, 2009, 11:17 AM
#14
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You are hearing the wastegtate puck cracking, or starting to lift off its seat inside the turbine housing. in your case, this noise is more pronounced since you have an open dump. The straight through unmuffled dump serves as a megaphone for that wastegate flapper valve as soon as it starts to lift.
Last edited by sparky; May 6, 2009 at 11:20 AM.
May 6, 2009, 11:30 AM
#15
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You could delay this sound and at the same time improve the spoolup rate on your turbo by increasing the spring pressure of your adjustable wastegate actuator. If I were running 25 PSI peak, then I would run at least 19 PSI of spring pressure. So, I would preload the WGA up to between 19-22 PSI. Thus, with higher spring pressure the valve will start to open later. You will still hear theventing noise but it will happen at a higher boost pressure.
