Vented BOV vs Unvented

[1997TsiTalon]

I have a 2g TSi AWD that I am putting an evoIII 16g in. I am currently running stock I/C pipes and a stock sidemount and 2g MAF. The BOV that I bought was designed to fit in the stock 2G setup, with slight modification. However, if my understanding is correct, it is vented to the atmosphere. There is a nipple on top and the inlet that sits in the I/C pipe. Other than that, there are like 8 holes drilled in the body of the valve that become exposed when the piston compresses. My t-25 went out before I got this valve, so I have never driven the car with it in action. My question is this: With the evo turbo/mani/o2 setup, will the vented BOV with the stock IC setup be ok, or should I get new pipes and go with a recirc valve like a 1g or type s? I understand the consequences of venting the BOV, rough idle and such, but will this be noticable. Also, if the vented one will work ok, should I get new IC pipes anyway, in which case I could flange it anyway I want. Just trying to figure out which would be best.

 

[blackGSX2g]

There will ALWAYS be side affects of venting a bov on the stock maf. Weather you can put up with them or not depends. From what I've heard, every car reacts differently to venting, but IMO its not worth it at all. I have a 1g bov vented, but I'm running with the GM MAFT setup. If you need tuning capabilities and want to use your vented BOV, I'd reccomend getting the MAFT. It eliminates the need for an SAFC plus you can hear the BOV. Only drawback I've found, is that you need to pop the hood to adjust...unless you mount it inside the cockpit. Performance gain was incredible for me, and gained about 500rpm spoolup on stock turbo. I've heard of more with a 16g.

 

[1993eclipseGS]

venting=bad

 

[1fast97gsx]

venting = rice if you are on the stock maf.

 

[1993eclipseGS]

My greddy type-s is alot louder then the stock bov vented, And mine is recirculated too! I admit I tried venting when I had my old car but it didnt go so well and it's not worth it just for a pshh sound.. just get an aftermarket bov if you want a diff noise?

 

[gixrman]

Under vacuum your BOV is sucking in dirty air(1g), if your going to vent go buy a K&N filter for $20.

 

[Lord Khan]

Like that other guy said, the Type-S is extremely loud, even when recirculated, so I would go with that. Venting will make your car run terrible.

 

[DSMeclipse4G63]

venting to recirculating is like fast is to slow....when you recirculate the air helps keep the turbo spooled. venting lets the air out and induces some lag, I tried both without driveablity problems and venting was so much slower.
Andrew

 

[L2RTSiAWD]

Dont' vent.