im pety sure compressor surge would destroy a small turbo. How much time would you think a s4 or s5 turbo would last with no a bov? week, month, year, day? some people don't run a bov at all because they believe it improves performance. i'm not here to debate on that subject but i am curious how a stock s4 or s5 turbo would hold up if someone was to do this.

-the reson i ask-
I have not purchased a bov. i'm runing the stocker but it's not being recycled... we all know the stock bov is always open a little at idle.. so i had to put a check valve on it.. ill be driving and not even in boost then let off and i hear compressor surge.. if i drive in boost and let off i hear the bov whistle but it gets cut short and i hear it surge after the whistle.. im staying outa boost until i get a aftermarket BOV but still want to know if i can occasionaly boost now and then between now and then.

 

compressor surge is normal, you just don't normally hear it on recirculated systems. our turbos tend to surge a little bit on low boost applications such as spool up on all the way up to about 2-3PSI or so.

 

karack thats some interesting information. I had no idea about this, thanks for that bit of information

 

i'm sure some people do not believe it or will disagree but i have noticed it on several FCs with stock turbos and stock/aftermarket BOVs.

on a stock setup it is near impossible to hear over the engine due to the way the piping sits and how the BOV dumps the air forward into the TID/AFM.

 

you make some good logical points and ya i was only boosting around 3 psi. it's reashuring that many other cars with this setup have the same symptoms, I was all worried today to stay out of boost. today is the first time i introduced pressure sence i did the swap. its a neat experience

 

The stock BOV is there purely to reduce intake noise, not extend it's life. The stock turbo on my 12AT lasted it's entire life 15-year without one, running up to 8psi boost. Compressor surge does not become damaging until you're running very high boost levels.

 

Yeah, you can boost here and there, but just don't get too greedy. Either that, or find a way to recirculate the stock BOV into whatever aftermarket TID setup you're running (I assume this is why you aren't recirculating).

Just drill a hole into your aftermarket TID pipe, thread in (and seal) a 1/2 O.D. brass fitting, then run a short length of heater-hose from your BOV to the fitting. Easy as that to recirculate.

 

Edit: You'll want a 1/2 I.D. brass fitting, or one that's roughly 3/4" O.D.

 

Or do it properly and weld a fitting on:

 

Oh yeah, or that.

 

thats a good example there. clear immage and almost imposible to misunderstand whats goin on in the picture. thanks