Where to install BOV?

[dustyk]

I just got a new blitz BOV and Im planning on welding the flange onto my intercooler piping. The question I have is where should I weld it on? I know that most people run thier BOVs on the hotpipe but Ive also seen the BOV on some cars right near the throttle. Is there benefit to either setup? SHould I install the BOV near the throttle body or the turbo?

[SR20DETPoweredS14]

I beleive the hotpipe is the only place to weld on a flange for a blow off valve but im not 100% sure... so far ive only seen BOV's placed on the hotpipe including the one that i also installed but if you do end up finding a way to put it near the throttle body try and get some pictures of it up because ive never seen them installed that way

[robbbby]

They can go on the hotpipe, or after the intercooler before the TB, it doesn't matter, it is the same charged system. I'd personally put it closer to the throttle body.

[Hijacker]

mine is set up to recirculate from the cold pipe (at elast that's what i call it since the air should be cold after passing through the IC). The main benefit I see from setting it up closer to the TB is responsiveness since you don't have to wait for the pressure build up to go back through the intercooler before it reaches the BOV. Of course, if you're venting, I guess it really doesn't matter where you place it.

[nismostate]

the advantage of having it closer to the tb is that it lets most of the air out at each blow off. otherwise it'll bounce back and you can risk compressor surge. definitely put it up close to the tb if you can. the bov on the hotpipe,imo, is just for show.

[PantherRacer]

I've seen them mounted in all sorts of places, good to know where to put one. for real.....closer to the tb will stop a wave of air from back flowing...mostly

[ultimatuc]

mine is on the hot pipe just before the ic. no problems here.

[RMiller]

the advantage of having it closer to the tb is that it lets most of the air out at each blow off. otherwise it'll bounce back and you can risk compressor surge. definitely put it up close to the tb if you can. the bov on the hotpipe,imo, is just for show.

That doesn't make sense to me. The air is pressurized everywhere in the system, it doesn't need to "bounce back" once it hits the throttle plate. There is pressurized air, even more so, right after the compressor. I dont believe the placement makes any significant difference. Put the bov wherever is most convenient. If I redo my setup I'll put it near the throttle body because I have more room over there and I can run a shorter vacuum line.

[floppycheif]

Air is pressurized everywhere in the system, correct. But it is not all the same pressure throughout the entire system. Throttle response is whats at stake here. Putting the bov on the hotside of the IC is imo the "wrong" place to put it. Let me explain.... Pressure is built right after the turbo, when the dv opens and the air escapes, the is a "dead spot" of air in your intake system, so pressurized air needs to fill that zone. Thus there is a short delay before the pressure fills that dead zone and the air is pushed into the throttle. As you can imagine, placing the bov/dv closer to the throttle body as a distictive benifit or anywhere on the intake path. (For those of you just reading and not thinking yet, bov closer to the throttle body means that the "dead zone" will have a fully {close to fully} pressurized system ready to blast the air into the tb with an almost instantanious response).

Hope that helped, and oh yes Hello Nico!

[89SilFourtysSR]

i have mine on the cold pipe too. works fine for me.

[240dreams]

i have mine about 6 inches away from the TB. I dont think it is as responsive as the hot pipe. but i do get slight compressor surge on low boost from it - i didnt have compressor surge on the stock recirc valve. Im going to redo my IC setup and put the bov on the hot pipe to recirculate.

[RMiller]

Welcome to NICO!

I still don't follow this logic. It sounds to me by the "dead spot" theory that having a bov right next to the throttle body would be worse for response because you would be missing out on air right where air is needed most.

I also forgot that putting it on the hotside makes it much more convenient for recirculating the exiting air. I have to do this since I use a pre-turbo maf.

I guess we could look to see what hardcore people do, like drag racers/track hounds and the like. What they do is probably the best.

[gtune4]

put mine right before the tb, works great.

this is where the air is stopped. this is where the piping begins to feel the surge. shortly there after(very shortly) the air pressure will reach the turbine, causing surge etc...

my thoughts are tb side is better for your sys and pipes, but it makes the throttle a little more touchy on the on off side of things.

hot pipe side seems to make the tb less touchy, but the over pressure that your bov has to recieve to open has to go through your pipes and intercooler first before hitting the bov every time.

[Gold Digger]

I am on my second turbo vehicle, and both of them have had the stock BOV close to the TB. The Eclipse had it on the cold pipe, and the Laurel, with the RB20 has it about 6-8 inches from the TB. I am still learning all the theories of turbo engines, and by no means an expert, but in most cars that i have see that have stock turbos, the BOV is always on the cold pipe.

This is a pic of my engine, and the bov is off to the side of the intake pipe going over the valve cover. That is not the stock bov, but it's the stock location.

[gtune4]

I am on my second turbo vehicle, and both of them have had the stock BOV close to the TB. The Eclipse had it on the cold pipe, and the Laurel, with the RB20 has it about 6-8 inches from the TB. I am still learning all the theories of turbo engines, and by no means an expert, but in most cars that i have see that have stock turbos, the BOV is always on the cold pipe.

This is a pic of my engine, and the bov is off to the side of the intake pipe going over the valve cover. That is not the stock bov, but it's the stock location.

this has been my experience too.

[RMiller]

Well, if oem puts it close to the throttle body that's probably the best place. But it makes it hard if you want to recirculate and have a front mount.

[drifting240]

i would put it next to your throttle body...it gets a better response and lets the air go faster...

[Gold Digger]

Well, if oem puts it close to the throttle body that's probably the best place. But it makes it hard if you want to recirculate and have a front mount.

What would make it hard to recirc, just run a rubber hose back to the intake side of your turbo...thats easy....my RB had one stock, but the owner before me removed it and pluged the hole in the intake tube.

[justmerging]

Well, if oem puts it close to the throttle body that's probably the best place. But it makes it hard if you want to recirculate and have a front mount.

Correct me if I'm wrong but isn't the OEM BOV on an SR motor on the hot pipe directly before the intercooler, or even on the actual intercooler itself.

I don't think it matters one way or the other as long as the BOV is tuned properly(for aftermarket).

[NIGHTfall_240sx]

[hannibal]

Ive thought about this before, but was never comfortable with my conclusion. I think the cold pipe is better. Here's why...Without a BOV, the air in the system will stop the moment your TB closes. Now imagine placing a BOV on the hotpipe. All the air past the BOV (bottom half of the hotpipe all the way to the TB) stops dead in its tracks beacuse it has nowhere to go. Only the air between the turbo and the BOV continues moving.If the BOV is on the coldpipe, all the air from the turbo, the hotpipie, the IC, and the lower part of the coldpipe continues to move. The only air caught in a 'dead spot' is between the BOV and the TB.So when you open the TB and the BOV closes, you have a large volume of pressurized air pushing a small amount of dead air into the intake. With the BOV on the hotpipe, you would have a small volume of pressurized air pushing a large volume of dead air.

Now that I write this, I realize this is exactly waht floppy was saying...