Forge Bpv Help

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ByrdMan23

Member
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Black mica, 07,MazdaSpeed 3
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?
 
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.
 
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.
 
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?
 
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!
 
ByrdMan23 said:
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!
Click to expand...

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?
 
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 said:
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?
Click to expand...

thats weird i didnt even know there was a green spring.. but i got the injen cai running and catback...
 
I'm pretty sure this is a dumb question, but how do you know if you are getting compressor surge?
 
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