http://216.239.53.100/search?q=cache:uzfKjn541bUC:turbobricks.saliv8.com/cbv_bov.html+my+blow+off+valve+stay+open+at+idle&hl=en&ie=UTF-8


If you use a SAFC and the stock bypass valve non-recirculated you can be sure you will have a pretty tough time tuning the mixture and part throttle driveability will suck because the stock bypass valve is open during idle and normal driving (non-boost).

whereas:

If you use a BOV drivability will increase greatly due to the fact that it remains shut during cruise and idle and all air will be accounted and fueled for.

whereas:

A stock bypass valve non-recirculated will draw in excessive (unmetered air) air while idleing (throttle closed) creating a lean condition and loose excessive (metered air) during steady cruising makeing it near impossible to maintain speed.

anyone know how much boost the BB BOV can hold before leaking air?

I don't know.

But I do know if you want to boost 15psi you should have a BOV that has a rated spring pressure 1-2psi above 15psi.

For instance let say you want to boost 9psi on the stock BB bypass valve so you disconnect the bypass vacuum signal line (so the valve doesn't open during idle and cruise) so the bypass valve now acts like a BOV and only opens once its predetermined spring rate is overcome by boost psi.

Problem is let say the stock bypass valve spring pressure 15psi (with no vacuum signal to aide in pulling it open at closed throttle) that means if your boosting 9psi, it is going to hold until the still spining turbo exceeds 15psi (if it ever does or forces it way back through the turbo causing compressor surge=bad) and then vent which should slow the turbo down considerably resulted in unwanted lag=bad.

yes, i know that.

so, does anyone know where the BB BOV starts to leak boost?

Mine is leaking at 5psi right now :(

I haven't had a change to put the SS BOV on there yet.