STS PVC switch valve question....

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Jun 4, 2009 | 08:49 PM

1BAD_LS1

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STS PVC switch valve question....

ok i bought this used STS turbo kit with a GT70 turbo.... I was looking reading through the instructions (thanks ZL1Killa) and noticed that the PVC switch valve is setup different on the kit i purchased. the previous owner had it setup on the wastegate and turbo (see picture).

What is the purpose of having it setup here? Will this hurt anything or is it better?

Thanks guys!

http://i721.photobucket.com/albums/w...1/IMAG0080.jpg

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Jun 4, 2009 | 10:52 PM

Karpellarpy

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STS kits come with 2 of those valves ... one is for the pcv, and the other is the "electronic boost controller". Basically, when the valve is not energized, the top port of the wastegate sees atmospheric pressure and your boost level will be based on your wastegate spring. When you energize the valve, aka "high boost", it sends boost pressure from the compressor exit through the air regulator and over to the top of the wastegate. This boost pressure helps the wastegate spring hold the wastegate shut longer and tigher, thus raising the boost level. So look around and see if you got another one of those valves with the kit that is used for your pcv.

Last edited by Karpellarpy; Jun 4, 2009 at 10:53 PM. Reason: spelling

Jun 4, 2009 | 11:05 PM

1BAD_LS1

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i have a pcv switch valve and pcv pressure switch.... in the intructions both are under the hood why is one of the setup back by the turbo? sorry im a total newb with boost.......

Jun 4, 2009 | 11:41 PM

koolaid_kid

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The "electronic" boost controller is an accessory and is not covered in the basic installation instructions. We put electronic in quotes b/c that is what STS calls it. It is actually an electrically actuated mechanical boost controller. But that doesn't sound nearly as sexy as electronic.

Jun 4, 2009 | 11:49 PM

1BAD_LS1

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So the black little (regulator) and the electronic pcv valve just help make more boost PSI by applying pressure with the spring to help hold the wastegate shut?

So the wastegate has a 8.7psi spring in it... is it possible for me to make only 5 psi boost? Or do i have to buy a different spring?

Jun 5, 2009 | 07:37 PM

Karpellarpy

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Quote:

So the black little (regulator) and the electronic pcv valve just help make more boost PSI by applying pressure with the spring to help hold the wastegate shut?

Yeah, that's the general idea.

Quote:

So the wastegate has a 8.7psi spring in it... is it possible for me to make only 5 psi boost? Or do i have to buy a different spring?

The boost controller can only add wastegate spring pressure thus upping the boost pressure. You cannot run less boost than what the wastegate spring produces. Even though the spring is 8.7psi, you will likely see a bit less. The picture you originally posted shows the wastegate referenced off the turbo's compressor outlet. Both the piping to the front of the car plus an intercooler (if you have one) will both cause a pressure drop from the turbo's compressure outlet and the engine which means the engine will see less than 8.7psi. With an intercooler, I'd say around a 2psi drop. Also even though the spring is rated at 8.7psi, some are tighter or looser than others.

Jun 5, 2009 | 08:33 PM

TurboAv

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That boost drop is why I referenced my wastgate to the manifold on my Avalanche. I also ditched the STS pcv system after it failed and blew oil all over my engine bay.

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