Hey everyone just got a quick question. I am pretty new to forced induction but from what I understand you want the BOV to be as close to the throttle body as possible correct? My 'JDM' motor came with a blitz bov right above the turbo, stock location Im guessing. But I am putting in a front mount intercooler, which would place the bov about as far away from the throttle body as possible. Is this going to give me any problems? I am only going to be running 10psi for a while, but down the road lets say 16-18psi, any issues then? Thanks

 

I don't think you will have any problems, as long as the BOV is working. Heck, its been argued that BOV's aren't even necessary. You should be able to weld or have a bung welded onto the piping that will mount your blitz BOV anywhere you want. Mine was placed between the intercooler and the throttle body and I was running 14psi with no problems.

 

number one, blow off valves exist because they are 100 percent necessary.

also, placement of the bov is, and some high hp guys can argue it all day, but for daily street drive, right where the stock location is 100% fine.

 

it doesn't really matter where the bov is.(hot or cold side of the pipe routing)

 

/\ +1 I prefer it on the hot side to get rid of air that has not entered the intercooler yet.

 

Ok thanks for all the replies guys. I was just imagining all the pressure in the system trying to go back the way it just came to the bov. I appreciate the replies.

 

Air is still going to backtrack. If the bov is on the tb side you don't have to wait for the intercooler to fill again.

I was always one for the turbo side, until I read this:

Rule of thumb is always put it as close to the TB as possible. Throttle plate is what causes surge, so dump it at that point or close too. If you dump right after the turbo, its gotta work a little harder to fill the IC and cold pipes (lag).
Best way to put it, if you dump on the hot side, the air that runs into the Thottle plate is still gotta make a 180 degree turn and come back down stream. If you dump right before the throttle, you get rid of that 180 degree turn.

 

The BOV will work best if it is installed in a high-pressure/low-velocity area, which means either near the turbo or near the throttle body. It will still work in the middle of the piping, but just not quite as well.

Most people who install a large front-mount intercooler tend to place the BOV near the throttle body so that the intercooler hopefully doesn't need to refill after the BOV vents. Most people who are still using the airflow meter and are running their engine properly with a recirculating bypass valve (very few people are smart enough to do this, lol) tend to mount the valve near the turbo in order to reduce the length of pipe back to the turbo. However, I think either method is fine.

Actually, a BOV is not necessary for many applications. A recirculating Compressor Bypass Valve (a.k.a. Air Bypass Valve) is necessary in order to keep an engine equipped with an airflow meter from running rich between shifts and bogging, but the engine will still run in this condition. If you look in the factory service manual, you will see that the stock air bypass valve simply "reduces sound of intake air from turbocharger relieved through air flow meter during deceleration". It is a good idea to install a BOV or CBV on high-boost engines in order to reduce the chance of surging which may damage a turbocharger's thrust bearings over time, but it is still not 100% necessary.

 

Wow, sorry about that. I remember reading somewhere on here that compressor surge is not that bad of a deal when it happens every once in a while. Sorry to pass on bad information...

 

You are correct, a little compressor surge isn't going to hurt anything unless you have one of those cheapie Mexican or Chinese Ebay turbos that are glued together. However, it's not such a bad idea to install a good bypass valve once you start upping the boost level because stronger-pressure surges can cause problems with the turbo.

 

I don't think placement of the BOV is that big of a deal. In OEM applications I've seen it before the intercooler and after. The FC and the FD both have it before the intercooler. The FD air bypass valve comes off the Y pipe which is bolted to the primary and secondary turbo compressor outlets. Yet the 3000GT has the BOV after the intercoolerand so do all the newer Subarus like the 06+ WRX and Legacy GT. The new Taurus has twin electronic BOV's before the intercooler, but the R34 RB25DET skyline has it after and so does the s14 SR20DET. Just about all these cars may be running at least 10-12psi for 100k+ miles without turbo problems if they aren't modded in any way. It seems that the OEM's put the BOV wherever it fits best given the packaging constraints.