Compressor surge under boost
 

I think I've read just about every post on here about compressor surge, but no one offers a solution to the problem of surge under boost when you gently roll off the throttle.

I have T04E dual bb turbo running about 11psi and a Tial BO valve with the lightest spring they offer. It blows off perfectly during shifts or low load roll off (when it gets into vacuum), but under load, say going up a steep hill, if I let off the throttle at all I get terrible surge. (The obvious answer here is to just floor it to top of the hill :-D )

Would going with an even lighter spring help this at all? I have a hard time believing this can't be fixed.

Thanks in advance...

Are you sure it's surge?
It might be the BOV oscillating from too light of a spring.

Try tightening the adjustment to see if this changes things?


-Ted

generally the bov needs to be loosened if it flutters. I have the apexi and i have it backed out almost all the way

TiaL doesn't have any adjustments....I had to trim their lightest spring to get it to work, even then its still a little to heavy for the rotary, I ended up robbing a spring from an auto trans shift kit, cutting it in half , and then it worked better.. What Ems is are you using, and do you have idle control? At first I was using a hard set idle on the throttle plates, but found that it weakened the signal to the bov, that way, you have the idle set at say 850 with the engine warm, and only use the bac valve should the idle fall below that, haltech and both the hitman advocate that setup and it probably works good with other bovs, But with the Tial, I left the throttle plates completely closed and used the bac to not only correct idle, but maintain it, it makes the signal to the bov quicker and stronger which minimizes the turkey gobble sound.. Incidently I was running it with a to4e as well...
When the tial is new, the pistons is a bit sticky withthe fresh o ring seals on it to, it will soften up a bit with time..
If you can luck out and find a spring , I found that its cracking vacuum has to be about 2" hg over idle vaccuum ....Its a great bov otherwise, no stupid sounds, just a woosh...Max

I'm running an E6X, but unfortunately I no longer have the BAC. The vacuum line for the BOV is coming off of a custom port where the BAC used to be. It's a pretty big line too. I tried cutting the spring down and that helped a little, but I think I'm going to go spring hunting in the morning and see if I can find something that will work.

Thanks for your replies.