BOV input needed: hot-side or cold-side?

[BlackZenkiS14]

So im finishing up my intercooler fabrication this weekend, and i was wondering which side is better for bov location? I had planned on putting it on the cold side, but i guess i should get some more information before i do it.

What is the benefit to having it on the cold side?

What is the benefit to having it on the hot side?

Any negative effects of either?

Thanks in advance for your input, and once i am finished i will post pictures of the whole fabrication process of it.

[youngmanvr4]

The best is to have it as close to the intake manifold as possible...but most 240's have them right after the turbo. The reason that its best as close the the manifold as possible is the flow of air thur the piping. The reason for a bov is to prevent back pressure on the turbo (everyone knows this), so if the air flows towards the intake manifold then when the value is open (throttle closed) then all the air the the piping will be rushing out.
Now if you place the bov before the intercooler (or right after the turbo) then some of the air will have to travel back, fighting flow, and make its way out through the bov. Remember, we're right to prevent back pressure, but when you place the bov near the turbo your actually making more back pressure per-inch of piping.

Just my 2 cents. Take it or leave it.

[BlackZenkiS14]

The best is to have it as close to the intake manifold as possible...but most 240's have them right after the turbo. The reason that its best as close the the manifold as possible is the flow of air thur the piping. The reason for a bov is to prevent back pressure on the turbo (everyone knows this), so if the air flows towards the intake manifold then when the value is open (throttle closed) then all the air the the piping will be rushing out.
Now if you place the bov before the intercooler (or right after the turbo) then some of the air will have to travel back, fighting flow, and make its way out through the bov. Remember, we're right to prevent back pressure, but when you place the bov near the turbo your actually making more back pressure per-inch of piping.

Just my 2 cents. Take it or leave it.

Thats what i was thinking as well. Thanks alot for hte input, i appreciate it. I'd also like to hear some other opinions too, so i have a well rounded understanding of it!
Im definately leaning towards the cold pipe though.

[johngriff]

I also like the bov as close to the T/B as possible. I have heard from people who have said that they get a stall after hard acceleration with the bov in this position, but I have always been able to correct for this by allowing more air in through the IACV adjustment screw.

The theory that young was trying to ellaborate on is pretty much correct, I would imagine the more irratic you made the pressure drop, and closer to the compressor wheel, the higher likely hood that could see turbulent pressure right up against the turbo. Moving it to the "cold side" would keep flow all in one direction all the time away from the turbo. You also can use a much much shorter vacum line, which I am kind of ADHD about.

[youngmanvr4]

Yup, the main thing is just to keep as much flow going the same direction as possible. That doesn't mean BOV's closer to the turbo are bad or dont work, just there is a better place for it.

I've heard the same about the stalling problem. But just like John said, it can be worked out. The only down fall is if you would want to recirculate the air then you would have to run a hose from the passenger side to the drivers side.

[projectRDM]

Exactly. On the cold side there's less negative pressure through the intercooler, but you end having to run a longer recirculation pipe.

[youngmanvr4]

But thats only if you run recirculation. A lot of 240's dont. So if your not going to recirculate and you have the choice; cold side is best. :)

[projectRDM]

True, and those cars also run slightly rich between shifts since you're loosing metered air. Nothing that can hurt though, just a note.

[youngmanvr4]

Good note to be noted.

[BlackZenkiS14]

the way its looking, i guess it's the cold side. I'll have to make sure we can fit it on the pipes though!

[youngmanvr4]

What do you mean by have to make sure you can fit it?

[NemeGuero]

Coolllldddddd

[BlackZenkiS14]

What do you mean by have to make sure you can fit it?

Well i made my own piping using pie-cuts and welds, instead of prebent sections of pipe. and i'll just have to make sure i can fit the flange onto one of the pies. You'll understand when i post pictures tonight.

[statik]

I moved my cold side when I had some down time

http://www.teamhpi.org/10-8-06/100_0447.jpg

I have noticed the car likes to stall more than when it was on the hot side

[g6civcx]

Search, please.

Cold side as close to the throttle plate as possible. If not, hot side for easy maintenance.

[jdizzy204]

is there any benefit to having two bovs? one on the hot side and one on the cold side like in this video.
http://videos.streetfire.net/search/jdmimports/0/455580db-148f-4040-b83f-78ab9b357e99.htm

[nsn240]

^No

I have mine mounted cold side with direct vac from the TB.. pretty responsive and i'll definately keep it there

[fromxtor]

I have mine setup on the cold side about 7-8 inches from the TB, and am running blow through.

[johngriff]

So, I was expecting pictures by now, its just piping and a bov! Hurry up!

[BlackZenkiS14]

Pictures are coming. We still have alot of work left to do. We just started on the cold pipe today, we are about half way done with it now. Once we finish the cold pipe, we will mount the BOV and start test drives. We should be done in a few hours. Pictures will definately be up tonight.

Im gonna make a new thread about the whole build of it later.

[kassed33]

before i installed mine i actually called HKS and asked them where they recomend putting it. They told me that it really dosnt matter which side you put it on, for mildly tuned cars pretty much which ever side you can fit it on. But they also said that most people with higher Horsepower #'s 350+ usually put in on the cold side because of the much higher psi in the piping. So i have mine on the cold side.

[youngmanvr4]

As far as stock, its really the design of the engine lay out where they put it.

The vr-4 has a very nice set up in my opinion has far as being close to the TB. Its about 5-6 inches from the TB, and still is recirculate. So it really matters on the engine layout.

[BlackZenkiS14]

done and finished. Lots of pics found here:
http://www.zilvia.net/f/showthread.php?p=1296406&posted=1#post1296406

[KwKouki]

the way ive always heard it

cold = better response
hot = better turbo life

[punxva]

mines on the cold side of my ka-t setup for better response, KwKouki, whats the explanation for the better turbo life on the hot side, since if its on the cold side it responds to the throttle closing sooner than if it were on the hot side, thus reducing compressor surge sooner?