GT2871 Surge with 710N BPV?

[popdemonic]

Mates,I'm just curious if this story is called surge?

Currently,I'm running on the GT2871R a/r 0.64.sometimes

when the car is under boost and then I let off the gas a bit.

I heard some sound like you're running the car w/o the dump valve.

It's not that loud but enough to be heard.one thing.I also have another

HKS SSQVII BOV laying around.I swapped her in.It seemed the sound

has gone.So I'm just wondering if it's called the compressor surged?

I have 1.9 bar WG spring with 3 more tapering on the top nut.I never heard

kinda sound while the turbo spooling up and the boost needle is rocky constantly.

No any flutteriing as the boost climbing at all.I also tested the 710N BPV.It's still

working great.Hold great on the vacuum.No leak on the boost.

I might try to unscrew the top nut on WG for a few turns though.

[popdemonic]

here's what I've learnt on the turbo Surge.Mine is not look like this.I have the issue only when I let off the gas slightly and only sometimes.

http://videos.streetfire.net/video/True-Turbo-Compressor_163406.htm

[KRIENG]

when the car is under boost and then you let off the gas a bit

pressure in upper chamber(vecuum line on top) and lower are different.
So BPV open a little and may be some noise.

I just know when I install HKS SSQV too.
when car is under boost I let off the gas a bit sound become PH.......H

[DJones]

What you have described is not surge, surge occurs under load not when you back off. I would say different DV which creates a different sound...

[popdemonic]

Well,I just got another of good known 710N.I'll try to swap her in and see if any changes sound when partially let off the gas.