Just got my Greddy Type S in today and put in on, i put it on soft setting and it still has compressor surge at normal shift ( 2k to 3.5k RPMs) it works great at high RMP shifting, like when i really get on it and im between 13 and 20PSI but other then that it will surge.....I know thats not a good thing. What should i do? I had a HKS back in the day on my GST and it didnt have two vac line mounts on it like the Greddy Type s does, ive got the main vac line on the big mount but there is still on open? idk what thats used for? Low boost shifting? idk, this is my first Greddy bov so help me out please lol

 

try the single spring mode or hook up both ports.

http://www.evomoto.com/tech_info.php?tech_id=7

 

Doesn't sound like Compressor surge, it sounds more like BOV flutter. Try loosing the BOV a little.

I have the same valve and at part throttle i get a little flutter.

 

Great info man, thanks alot....It helped out alot!

 

hmmmmmmmmmmm

 

I think your talking about flutter, check the spring setting.

 

+1

 

start at 2 screws in from contact

 

glad its working out for you!

 

Isn't it normal for all aftermarket bov's to flutter a little at low rpm? I got a GFB bov and it flutters too after i set the springs soft. Even my friends stock 9 bov flutters lol

 

Could be the flutter but then again it sounds a hell of alot like surge, but i love the way it sounds. I just dont want to **** up my turbo, even tho im looking into getting the Evo 9 upgrade. Still doesnt mean i want to **** up mine tho lol.

igo4bmx, did it do that for you before you took it off your setup?

 

Yes.

Compressor surge happens when the turbo's compressor is "asked" to produce a greater pressure ratio than it can sustain at a given volume of flow. Essentially the compressor wheel cavitates and unloads the turbine, and a spike in turbo rpms occurs.

It doesn't occur when you lift off the throttle - it occurs when you're getting ON the throttle (so that the turbine is spooling up) at a low-ish rpm (so that the airflow demands are relative low).

What occurs at throttle lift-off is either blow off (to atmosphere) or recirculation (back into pre-compressor inlet hose).

Again, your issue is not compressor surge. It's BOV flutter.

Hope this helps!