Corky (over at m.net) said he's never seen a damaged compressor from not having a BOV. Also, he doesn't believe it's possible for the compressor to get damaged w/ lack of a BOV.

I have. My friend still has the big ass fp green turbo we took off his sti after it shit itself. vacuum line going to his bov melted, and for a while he didnt have a bov running 22psi on the sti. hes an idiot and didnt realise till it was too late. I can try to post up pictures of how raped his turbo is. shaft is bent so bad the compressor wheel grinded against the compressor housing shafing off like 2mm off the wheel. its horrid

Corky:
In my time I've never seen a surge induced turbo failure. At present I do not believe it possible to hurt a turbo by not having an anti-surge valve.

Porsche did not use a-s valves on their Le Mans winning turbo cars. One Le Mans race is probably equivalent to about 3,500,000 street miles.

A slight improvement in boost response can be attributed to the a-s valve. So can noise suppression. That's about as far as it goes... i my view.


I have yet to see a turbo suffer from no valve. I do not believe it possible to fail a turbo because of surge.

that interesting. I have a forge bov waiting to go in on my car, included are 4 springs. so the weak ass yellow spring that barely holds the thing shut is still causing your car to surge? thats not good

Not taking away anything from you or your friend. I just quoted what I read from Corky at m.net.

I wont argue with "THE MAN" but I sure do disagree....
I hear ya man, I would never argue with Corky either. I would love to hear an explanation of how his turbo failed then....weird

I get compressor surge as well. Although, it is at low boost levels. My old HKS unit failed completely and was only venting under high boost conditions. So, I replaced it with a new HKS unit. Now, it vents 100% under all conditions, but there is still compressor surge. I am not going to worry about it until if/when something happens to the turbo. FWIW, I have had that mild surge since I installed the set up a year ago, and it is my DD. I haven't had any problems with the turbo at all.

It doesn't surge nearly as bad as either car in the videos. Most people would probably let it go. According to the Forge site though, the yellow spring's lowest boost threshold is 15 psi. The kit isn't expensive at all so I figured, at 12 psi, I might as well drop in the green spring just to be safe.

Like m/n said, I get absolutely no surge. I can induce it to a tiny bit if I try hard enough. I'm running a 14b with a recirculated knockoff Type S.

I bet recirculating helps a bit.

I've seen a turbo or three destroyed by surge. I half agree with corky though. the ones I've seen were marginal at best. meaning that they were within spec, but had a little more longitudinal slop than I prefer. in short they all made contact with the compressor housing and started to eat up fins from there.
in my original setup I was using a greddy type s, but I had to put quite a bit of preload on it to keep it from leaking at Idle. it wouldn't gobble, but it would give me one high pitched surge noise upon blowing. as a result my 16g has more for and aft play than it realy should, but since switching to the turbosmart valve it hasn't gotten any worse in three years.

See, mine is almost all in vac while its spooling but not actually in boost yet. or at MAYBE 1-2 lbs max. I can sometimes hear a different sound when it DOES blow off....idk, this turbo stuff is strange. Not enough time in the car yet, to much time in my beater BMW.

Hmm, strange thing:

I Got the Forge Spring Kit. I checked my current spring (yellow) to see how much the BOV was leaking at idle. No leakage whatsoever.

I installed the green spring and the BOV leaked like a sieve. The piston shut with a loud click when I turned off the engine. I installed 4 shims and it still leaked like a sieve.

I installed the yellow spring that came with the new kit and it leaks too. Not as much as the green spring with the shims but definite leakage with an audible click from the piston as it shuts when I turn off the engine.

I shouldn't have too much trouble figuring out the correct spring setting, but it's interesting that there would be that much difference between springs/sets.

Make sure the spring side you put against the piston is a ground flat side. If it is not it can make the piston slightly crooked in the bore and it may not seal properly.

I dont know why you guys care so much if it leaks at idle, I have tried everything on my TurboXS its the only way to prevent the slight flutter at low boost.

I'm not concerned about leakage at idle. A lot of leakage, sure, but leakage in general? No.

It's just interesting that a yellow spring from one set would cause fluttering because it shuts too tight, while the yellow spring from another set would allow a whole lot of leakage. I'll check the seating fo sho.

18psi seemed interested, so I'm just dropping in a little fyi.