So...Where's your BOV?

[Trppen37]

Ive seen some people put the BOV BEFORE the intercooler and and some AFTER the intercooler. Im considering welding it to the charge pipe and putting it before the intercooler .... i got a starion intercooler... also for the vacuum lines where did you hook it up to? thanks...

[gyfer]

I see you have a SOHC.Just before the throttle plate, on the throttle body, I disconnect the line, and hook it up with boost gauge. Not sure if this is a good place to hook it up with wastegate or not.... but I did on mine.

[Trppen37]

do you have a KA24E?? so u hooked the BOV to the boost gauge which then goes to the TB right? and your BOV is AFTER the intercooler am i correct?? Ive been reading that the closer to the TB the better...but ey I dont know jack lol..wheres everyone else?

[gyfer]

I guess it is still too early for everyone else..

Yes, I have a KA24E. Just finish my turbo proj and putting my bumper on yesterday ( is a bi.tch) I will answer your most question while my memory still new.

I got a vacuum-T from auto store. I spit it to boost gauge and wastegate.I don't think BOV line is before throttle plate. It should be after the throrttle body, which mean from "intake manifold absolute pressure". BOV works when you lift your acceleration, which close your throrrtle plate, and create a vacuum inside intake manfild( nagative BAR ), and sending the signal to BOV to open the valve ( or get ready to open ), so when the wave hit back, the BOV will open up and psssst of extra pressure ( instead of hitting your turbo turbine )

[Trppen37]

well im in Kuwait so its not early for me lol! yea the bumper is a bi0ch took me almost a day just to switch from a 90 bumper to a 91 bumper! as for the BOV Line if its after the throttle plate , where would this vacuum line be? im thinking somewhere in the intake manifold??

[gyfer]

There is one...err.. next to power steering pump.Unhook that one and use it ask "vacuum" line ( not boost ).

[gyfer]

But your info said you are from North Dakota.in Military ?

[Trppen37]

Yes United States Air Force ! whoo hoo..... :oface

[Xero]

the ideal place for the BOV is just after the throttle body, since it'll let off air before it backs up to the intercooler, since if you're running insane boost, the interooler COULD (probaly not, but the possability is always there) blow up. Lots of people put it just after the turbo 'cause it's easiest to do, for a lower boost situation, both works, but the air is backing up from the TB back towards the turbo, and you're trying to save the turbo, so the closer to the TB the better,

[C-Kwik]

I'd love to see some technical data. I've thought about this before.

My thoughts: before the I/C.

Reason 1: Heat. Putting a BOV after the I/C means the I/C has to cool air that will never see the motor. I'd rather not add more heat to the I/C then is effective and necessary.

Reason 2: This is more speculation and a contradiction to what some of you have stated. But the point of a BOV is to prevent or reduce compressor surge. The surge takes place within the turbo. Pressure is also higher near the turbo. Mounting the BOV closer to the T/B would allow pressure to get higher near the turbo. As far as response, it has more to do with the vacuum signal vs boost pressure. Since boost pressure is higher in the hot pipe, I would speculate faster response closer to the turbo. Though, if the BOv is closer to the TB, the boost response after shifting may be a bit faster since more of the piping may stay charged. I'd assume there are compromises to both locations. And again, I'd love to see some technical data to support different theories.

As far as intercoolers blowing, I'd probably only worry about factory intercoolers having problems with this. Most aftermarket units sport welded aluminum end tanks and should be able to support relatively high pressures with ease.

[Xero]

well, think of it this way. When air is flowing at WOT, its at teh same pressure throughout the piping. When you slam teh TB shut, it's going to 'cause back up from the TB 'cause that's the variable that changed, so air is going to stat backing up from the TB, not the turbo. so ideally the BOV should be closer to the TB.

Your concern about IC strain is something I didn't really think of, but what would you rather blow off into the engine bay, hot air or cool air? the hot air will go straight to the intake and then it'll get even hotter, so the IC will have to cool it anyway. ESPECIALLY if it's a recirc valve, it'd need to be on the TB side, so it's already cool,

[huguetpj]

Xero does have a point, since I'm gonna go with recirc most of the time... gonna go atmospheric only when I want to make some noise... would I want to recirc hot air or cold air? But then you would have to take into consideration heat soaking the intercooler since you would be recircing the air through the heat source several or at least a couple of times.

I don't think response would be an issue since it'll probably be less than .5 seconds difference between the two places.

I'm still thinking of going cold side, about 6" before MAF if going blow through or next to TB if going draw through, just because the surge wave initiates there.

Although as C-kwik says, some technical data would be great, don't really think we're gonna get any :pface

[huguetpj]

well, think of it this way. When air is flowing at WOT, its at teh same pressure throughout the piping.

Pressure through out the piping will not be the same since you do have pressure drop alog the pipes and mainly at the intercooler.

[Xero]

^^I know that, but using my example if I would have thrown that into the mix it would have gotten alot more confusing,

[cnichols]

Run one in both places...problem solved.

[erich]

Right here on the cold pipe:

[C-Kwik]

I agree that recirculating does set a new set of issues, but in actuality it should be somewhat negligible in terms of heat. Recirculating hot air will increase heat by the efficiency of the boost and there for be about 20-30% hotter. If it continues to recirculate the same air, it would keep heating itself up. Of course some of it will be diluted by incoming fresh air. But regardless, the hot air would eventually have to go through the intercooler.

If mounted on the cold side, the intercooler will have cooled the air down, but have absorbed some heat in the process. Either way, ultimately the same heat (energy) would have to be absorbed by the intercooler.

As far as venting hot air into the engine, it will be diluted by the air that is already there. I'd suspect as long as the BOV is not aimed right into the filter, a very small percentage of it would be taken in by the motor. Some careful locating of the filter and BOV and perhaps some trick piping or baffles may reduce or even eliminate this effect.

If I were desiging a race turbo motor, it would incorporate a open BOV though.

I understand what you mean about the TB. I picked up my June issue of SCC and in the Compressor Bypass test they did, they mention the TB side is better, but offer no technical reasong as to why. So it's a possibility the TB side may be better, but I still speculate that the higher pressure of the hot side may pose more surge. If a BOV releases based on pressure differential between the vacuum signal and the pipe pressure, I would think you would want to release from the point where pressure builds the fastest. But again, this is where technical data would be useful...

As far as the I/C, I highly doubt an engineer was thinking to use a BOV to keep a I/C from blowing up. If an I/C does fail, it was either poorly made or just seeing pressure beyond it's design. The BOV is really a fix for the compressor surge problems. Turbos got a bad rap with early turbo motors because of frequent turbo failures.When factories started using DV's(BOV's) in their turbo motors, reliability went way up.

[SingleCamSam]

So is there anyway you can mount your BOV and have no problems? Or are you going to get stumble with both blow and draw-through MAF locations?