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ByrdMan23
08-13-2008, 02:11 AM
im sure this has been beaten to death but hey.. surely we run short on things to talk about on here sometimes so please dont kill me too bad...

i got the forge bypass valve and im just wandering the difference between all the springs and whats the best for the ms3.. also i dont really know what the shims do and all that...i want it to be loud as possible without surge, any help?
john blutarski
08-13-2008, 07:46 AM
The difference is their stiffness. For most stock or mildly modded MS3's, I've seen the blue spring used most often and one or two shims. I personally use the blue + two shims and it works great. The shims are just a way to make the spring stiffer... so it falls somewhere between using the blue by itself and using the red by itself. If you run too stiff a spring, you may get compressor surge. I do get a slight surge but only at lower rpm in higher gears which I rarely do anyway.
SwampAss
08-13-2008, 10:20 AM
Blue spring no shims. I get flutter on occasion but it holds boost well.
MikeHTally
08-13-2008, 10:44 AM
Blue spring and one shim. My car seemed to be a bit stronger as it approached power peak.

Not sure if the springs affect loudness. I'd think they'd have more effect on when the "ting" comes out.
CWPspeed3
08-13-2008, 12:29 PM
I have to buy one of these...
If I'm not mistaken isnt the blue spring for "stock" boost, yellow is slightly higher 15-25psi and red is 25+ or something?
john blutarski
08-13-2008, 12:51 PM
I have to buy one of these...
If I'm not mistaken isnt the blue spring for "stock" boost, yellow is slightly higher 15-25psi and red is 25+ or something?

I think yellow is the softest, blue in the middle and red the stiffest
CWPspeed3
08-13-2008, 12:53 PM
I think yellow is the softest, blue in the middle and red the stiffest

Oh, my bad.

Do you happen to have any videos of your car, I've got the cobb sri and trying to decide between the forge and turbo xs.
08cosmic3
08-13-2008, 10:02 PM
Blue with 2 for me. Must have mod.
ByrdMan23
08-13-2008, 10:57 PM
you know whats funny.. forge sent my bypass valve with the yellow spring inside and the only other spring i got was the red one......omg.... haha so i have the yelllow one in with 2 shims cuz it surged with the red one so now i have to get them to send me a dam blue spring, the one that everyone recomends naturally!
Speed3Rookie
08-13-2008, 11:58 PM
Blue w/two for me.
john blutarski
08-14-2008, 07:04 AM
Oh, my bad.

Do you happen to have any videos of your car, I've got the cobb sri and trying to decide between the forge and turbo xs.

sorry, no vids... all I can say is the Cobb SRI with the Forge BPV is a sick combo.
MikeHTally
08-14-2008, 07:12 AM
you know whats funny.. forge sent my bypass valve with the yellow spring inside and the only other spring i got was the red one......omg.... haha so i have the yelllow one in with 2 shims cuz it surged with the red one so now i have to get them to send me a dam blue spring, the one that everyone recomends naturally!

There does seem to be some inconsistency... mine had the yellow installed with the red, blue and green in the bag with the two shims. On a side note regarding maintenance/lubrication, when, where and using what?
john blutarski
08-14-2008, 07:26 AM
On a side note regarding maintenance/lubrication, when, where and using what?


Here you go:

The servicing instruction can be found here:
http://www.forgemotorsport.com/media/valve_service(1).pdf
ericrapp
08-14-2008, 07:04 PM
23. the springs I believe are related to the boost pressure. The shims are to incrementally reach the tension of the the next spring. Patty at Forge is the source for all info. The yellow is softest, blue, then red. ADD shims to yellow to increase tension. After two shims on yellow, you might move up to blue if you are trying too run more boost than stock does that help?
MikeHTally
08-14-2008, 08:01 PM
Here you go:

The servicing instruction can be found here:
http://www.forgemotorsport.com/media/valve_service(1).pdf

Eggselent, thank you. How often should this be done? I didn't see a service interval mention. Presumably once a year?
ByrdMan23
08-15-2008, 01:44 AM
There does seem to be some inconsistency... mine had the yellow installed with the red, blue and green in the bag with the two shims. On a side note regarding maintenance/lubrication, when, where and using what?

thats weird i didnt even know there was a green spring.. but i got the injen cai running and catback...
ericrapp
08-15-2008, 06:57 PM
Green? nice work Mike!
MikeHTally
08-15-2008, 07:40 PM
It's the Al Gore spring. (rlaugh)
jlocurto
08-22-2008, 01:48 AM
green is for like 30+ psi i think
gbalanced
08-22-2008, 10:53 AM
I'm pretty sure this is a dumb question, but how do you know if you are getting compressor surge?
john blutarski
08-22-2008, 01:05 PM
I'm pretty sure this is a dumb question, but how do you know if you are getting compressor surge?

You will hear the compressor wheel stall out from pressurized air going back against it.. its kind of a pff, pff, pff quick short frequency sound. This is different from wastegate flutter which is when the wastegate door is fluttering open and closed trying to maintain a certain boost level. Flutter usually occurs at low boost on/off throttle situation. Surge is most noticable when building boost from a high load at lower RPM in a high gear like 6th for example. You shouldn't do this anyway but if you were to lay on it around 3k in 6th, build boost and then let off right away at say 4k, you should hear some surge depending on the valve/spring you are running.