Just a thought on this
"Basically, a bypass valve exists to relieve a residual amount of boost pressure in a pressurized application when the throttle on the application is abruptly closed preventing the air from “backing up” into the compressor wheel of the turbo, slowing it down, thus creating “lag” when the throttle is reapplied. "

I agree with this, but also to...correct me if i'm wrong, doesn't the sudden surge back of the air also put added stress on the bearings in the turbo as the in rush of the surge hits the impeller blades, thus reducing turbo life?

 

Mike -- I seem to get "bucking" when ~3800 rpm ~ 10 - 13 psi part throttle conditions (e.g. going up a hill and just wanting to maintain speed). This is happening with the Blue spring installed - should I use a softer spring or a firmer spring ?

My setup is a stock 9 turbo with peak boost ~29 tapering to ~22 at redline.

 

Put the stock spring back on with the stock valve around it.

 

Sorry I am a bit confused with your response. Do you mean to replace the Forge with the stock DV or are you stating to place a softer (yellow spring) or something else? TIA

 

Dump the forge go with the stock IX valve. Forge valves are great for drag racing but for street or road course they suck.

 

keith, ive read ur entire post.. very nicely detailed...i have a bad idle problem..i start it up and it idles at 3k..once it warms up to becomes a fast surging idle between 2500-3000.. last time i had this problem the motor blew under hard vacuum..since then i had the motor built ..it was running fine..now the 1st time i got on it.. i went through all gears hard.. now the problem is back with new motor... now by reading ur thread im starting to believe it may be the bov.. i have the turbosmart 50/50...it has about 60k miles on it ..orginal spring...did a smoke test and found nothing..can it be anything else?

 

Did you smoke test the pressurized side? That side is sealed, I'm sure . . .

You need to smoke out and pressurize the intake side that is common to the 50-50 vent. Here's a hint, how do you seal around a cylinder, you don't. I think that's where you'll find your MAF leak. Pretty common with these 50-50 designs.