Specs:
2.0L B18B
9.0:1 Compression pistons
GT3251 Turbo in T3 housing
Tial 38mm WG
Tial 50mm BOV w/11 pound spring

According to Tial, if the car idles between 18Hg and 21Hg, you should use the 11 pound spring. My car idles at 19Hg and I am getting compressor surge at low boost.

What spring should I switch to for proper BOV operation? 9 pounder?

 

When you get the surge, are you slowly letting of the throttle or is it a rapid release? When I would slowly let off I was able to get surge. I also had the 11lb and 18-20 in/hg. I never broke anything and drove it for more than a year before it was taken from me.

If it is the rapid release, get the 9lb. If not, I wouldnt worry about it.

 

that soft flutter you here at ~.5-2psi is nothing to worry about, it's not actually surge... the term "compressor surge" gets thrown around here A LOT, compressor surge is a very violent thing and usually leads to a turbo's death...

 

Surge def gets thrown around, but from what i've come to understand is that there are two types of surge, they type shore is speaking(pressure forces the turbine to spin backwards) of and the violent type(from to much boost for given rpm) blinx has described.
I had the same problem with my tial not opening under light boost and I would hear the flutter surge. I have the unpainted 11lb spring, I was hearing such good things about the synapse bov that I switched, Its a decent bov with excelent response, I mean NO flutter at all and I mean NONE. However its constently open during vacuum, somethin I do not like. gettin off topic, anyway if you decide to go with the 9lb spring post up your outcome, I would like to know. thanx

 

There is only 1 kind of surge.

 

where are you pulling the source from?

 

I seem to be having the same issues with an 11lb spring and a similar setup as the OP.I'm also wondering if I should use the 9lb spring.I've tried the source from the back of the manifold and a vacuum block with the same results.In for more input

 

uh, trying to be a smartass maybe???

their is only one KIND of surge, but a few CAUSES of surge...

the most dangerous being this kind...

http://www.youtube.com/watch?v=nCj6Spwl1CU

 

 

 

hopefully tial will chime in on this, but i have heard with the propper spring for the aplication the tial bov's are supposed to be open at idle as well. is this correct?

 

The ideal BOV will open with any vacuum when pressure is pushing on the valve, but will just barely stay closed when it idles (high vac, 0psi under bov valve).

If the bov is upen with the 9lb spring, you might have to modify the 11lb spring. I tend to doubt it will leak, give it a shot.

 

That video shows surge, everything else is just meaningless noise. So whats the problem? Im attempting to educate people and your jumping all over me, are YOU trying to be the smartass?