Minimum spring pressure for BOV

[Boston Racing]

I am running a Silber BOV and have a few questions. Justin has been out of town so I figured Id ask here. What is the minimum spring pressure needed for a BOV? When I got it from Silber it would open with 5 inches of vacuum. When riding it I noticed it rarely ever blew off. Only at full boost and when you chop the throttle. I put a lighter spring and now it sounds like it works all the time, however I cant get over 10lbs of boost. Im thinking I have the spring too light now. I cant tell what its set to now, as soon as you pull the vacuum lever it pulls open the piston.

This is on a T660 so I dont know if it pulls less vacuum than the 800.

 

[tree climber]

you really only need enough to hold the valve shut by my understanding. under boost the boost should pressureise both sides of the valve to hold it shut under boost. so maybe its your vacuum line? leaking or not sealing good. i cut my spring in my bov just so it was long enough to hold the valve shut but pops off whenever i let off with any kind of boost and no problems building pressure

 

[Eli]

I also think most blow off valves have a piston that has a larger surface area on the source side so that there will be a positive sealing pressure even when the pressures are equal.