ive been trying different combinations of springs/shims on the bpv and it seems that blue spring with two shims holds boost better than just the blue spring, for me at least. I don't have a boost gauge so i'm just using my butt dyno, but i do get fluttering with this setup. It only happens sometimes and at about half throttle if i quickly release it. Should i just use 1 shim or even just use no shims at all .. or do you guys think i should just leave both shims in?
I run blue with 2 shims its fine.
From Forge...
If valve fluttering is felt at full-boost throttle lift, this is typically an indication that
the valve is adjusted too stiffly.
If the valve is leaking under wide open throttle before the specified redline of the
application is reached, this is typically an indication that the valve is adjusted too
softly.
Please note that valve flutter under partial throttle conditions or partial boost throttle
lift is a normal occurrence as IS NOT an indication of compressor surging. Partial
throttle or partial boost valve flutter is solely an indication that the valve is
responding to an inconsistent pressure differential on either side of the throttle body
as it is being modulated. Compressor surging would only be experienced if full-boost
throttle lift valve flutter is experienced and is not corrected immediately.
