Question..... Why bov on cold pipe vr. hot pipe

[Delearious02]

Well that is my question..... why do i see some BOVs on the hot pipe and others on the coldpipe? Just wondering.... im no tech wizzard.... so help me out would ya? anyone?

[Nicksemianiw]

Mostly preferance, but the closer the bov is to the turbo outlet the less stress is put on it from a boost surge.

[kingtal0n]

Dont forget there will always be slightly more pressure on the hotpipe side than the cold pipe side... therefore a push type bov (like the type-S) will have that much more chance of leaking on the hot-side.

On the other hand, response will be better on the hot-side mainly due to the high-velocity and smaller pipe size (most fmic manufacturer use smaller hotpipe diameters) -

The closer the bov is to the turbo the better response and surge prevention will be.

[Nismo_Freak]

On the other hand, response will be better on the hot-side mainly due to the high-velocity and smaller pipe size (most fmic manufacturer use smaller hotpipe diameters) -

LOL, the size of the pipe has little to do with how quickly the BOV depressurizes the system. It's simply a hole in a pipe once it opens and pressure is vented very quickly.

You aren't trying to purge the entire system you are trying to reduce the pressure after the compressor. As long as you don't hear audible surge the BOV is doing it's job.

[2_Liter_Turbo]

So if the BOV being as close as possible to the turbo is the best, then why is that the DSM cars run their BOV's after the intercooler and before the throttle body? Is it just that it's a bad design, or is their a reason behind it? Also, aren't the factory SMIC on SR20's blowoff valve locations right after the intercooler?

[cyfiro]

Ideally the BOV should be after the intercooler and before the throttle body. The DSM cars have the perfect setup. Less stress on the BOV because it's sitting after the intercooler and away from the hot charged air of the turbo. Being closer to the throttle body will result in quicker throttle repsonse and less of a chance of compressor surge and thus less stress on the turbo itself.

[compression]

Ideally the BOV should be after the intercooler and before the throttle body. The DSM cars have the perfect setup. Less stress on the BOV because it's sitting after the intercooler and away from the hot charged air of the turbo. Being closer to the throttle body will result in quicker throttle repsonse and less of a chance of compressor surge and thus less stress on the turbo itself.

he is on the right track....

when your throttle body slams shut a pressure wave is created right there and it travels backward through the system, then smacks into the turbo (surge).Putting the BOV right by the throttle body (where the pressure wave is created) is the most effective place.

But we are splitting hairs here, put it wherever it fits and is not exposed to high heat anything like that. Your car will run exactly the same.

[2_Liter_Turbo]

So Ideally you would run your BOV on the cold pipe near the throttle, and recirculate it back to the intake. But most people run it on the hot pipe because it is easier to recirculate, because the cold pipe is way on the other side of the engine bay.

If that is the case, what is the most effective way to route the plumbing to recirculate the BOV off of the cold pipe?

[Scooby24]

So Ideally you would run your BOV on the cold pipe near the throttle, and recirculate it back to the intake. But most people run it on the hot pipe because it is easier to recirculate, because the cold pipe is way on the other side of the engine bay.

If that is the case, what is the most effective way to route the plumbing to recirculate the BOV off of the cold pipe?

Recirculate the BOV back to the intake pipe AFTER the MAF but BEFORE the turbo.

The air has already been metered so you don't want to have it metered again by going back through the MAF a second time...would run lean.

The recirc pipe does not need to be metal since there isn't a huge amount of pressure on it. If you can find some silicon tube use that.

[turbo_lover]

ive heard you keep it on the cold-pipe, like, 12-13 inches before the throttle body.

[Scooby24]

ive heard you keep it on the cold-pipe, like, 12-13 inches before the throttle body.

FYI from the factory an STi's bypass valve is about 4 inches from the throttle body on the cold pipe.

If a factory car puts it on the cold pipe a few inches from the throttle body that's where I'd stick with it.

[tgm]

On the cold pipe would be ideal, the closer to the surge i.e. throttle body, the better, why would you want a surge to go through your intercooler and then to the bov, that seems counter productive to me.