[s-cars] Re: Bypass Valves and Pressure Losses - the basics first

[CaptMagu at aol.com]

Gee Scott

Let me see if I can explain this to you. When I say boost surge at throttle 
lift, I'm talking about too much chharge air in the plumbing before the 
throttle body. This happens before I get to vacuum on the other side of the throttle 
body and consequently before the BPV opens to vent this excess pressure. This 
is manifested by a surging and sort of bucking feel. The last few steps i've 
taken in shortening and softening the BPV spring have had a dramatic effect to 
improve but not totally solve this problem. I experimented with a too short 
spring that allowed the BPV to stay open a little and the problem disappeared 
totally. This has nothing whatsoever to do with the wastegate!!!

Hap, tryin to expain to old SJ in Everboost, Magfuire