KamikazeSol

I did a search, but found only opinion on the topic. I need any real facts that help to suport what is the best place to put the blow off valve. I am redoing my charge piping and am thinking about moving the valve to just after the intercooler outlet to clear up some room in the engine bay. The vlave now takes up the space that would be perfect for my boost controller box. Running out of room in the engine bay. Keeping A/C and powe steering does not make it as easy to add all the parts to support a turbo system.

BROOD

Mainly as long as it is in the system somewhere it will do its job. It sounds like you are planning to move it from "just before the throttle body" to "just after the intercooler outlet". The change is not much, if anything. Go ahead and move it if it allows better engine bay packaging.
The usual debate is between installing the BOV before the intercooler or after the intercooler, is one better than the other and which one?
There are alot of opinions/facts/info/etc but the differences are most likely negligible.

You have IM

**I choose before the intercooler, mounted directly on the inlet endtank.**


Modified by BROOD at 1:49 PM 11/24/2003

KamikazeSol

What are yoyr reasons. I am interested in different view pionts.

yellowturbo

right in the middle ... you cant go wrong !

guymosiris

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BROOD &raquo;</TD></TR><TR><TD CLASS="quote">Mainly as long as it is in the system somewhere it will do its job. It sounds like you are planning to move it from "just before the throttle body" to "just after the intercooler outlet". The change is not much, if anything. Go ahead and move it if it allows better engine bay packaging.
The usual debate is between installing the BOV before the intercooler or after the intercooler, is one better than the other and which one?
There are alot of opinions/facts/info/etc but the differences are most likely negligible.

You have IM

**I choose before the intercooler, mounted directly on the inlet endtank. I have my reasoning**


Modified by BROOD at 7:00 AM 11/7/2003</TD></TR></TABLE>

Yes, what are these reasons? I need to learn more about this subject.

ridnmyhonda

I dont think it mattes as long as it is on the pipe from the IM to the IC.

NuclearB18B

mine is right after the fmic outlet. right under the coolant resivoir tank. had to do it because you can't weld steel to aluminum...works fine though.

T4sol

back from the dead....would like to know the advantage of placing the bov before the intercooler...or on the endtank of the hotside?

PrecisionH23a

The closer to the compressor the better, since the whole point of having a BOV is to reduce compressor surge.

The other reason why it is better to have it near the compressor before hitting the intercooler is because you will be releasing hot air in the charge pipes instead of the 'cold' air going to the TB (since this air has already been cooled due to the intercooler).

kpt4321

Why is it better to release hot air than to release cold air?

You want it after the intercooler. When you are at WOT, the air is moving at a high velocity through the intake track, towards the throttle body. If the BOV is near the throttle body, the air can continue on that path and simply be diverted out to atmosphere. If the BOV is near the turbo outlet, then the air has to hit the throttle body, surge, and then you have to hope that all of the surge waves get caught by the BOV on the first pass and don't hit the compressor.

The best setup would be a BOV after the intercooler to get rid of that large volume of air, and one after that turbo so that it could "freewheel" when you are in mind-shift. However, not many people want to do that, and if you're only using one after the IC is best.

On any stock car with a BOV, it is located after the intercooler. The engineers are Subaru and Mitsubishi know what they are doing when it comes to turbo cars.

Blitzkrieg

As close to the compressor as possible.

30psi Teg

I dont think it really matters as long as its somewhere in the charge piping so that it can get rid of pressure when it builds up due to closing throttle body under boost.

kpt4321

Did you two even read my post?

BROOD

Yea, I read it.... I disagree with some of it. Last time I checked my BOV does not open at WOT. Plus I do not agree that air moves in this manner, at least it does not remain in check with what I work on everyday. But that is cool, it gets people to think about it.

Plain a simple, mount your BOV anyway you want. It is more important that it is "somewhere" in the system. Discussing the benifits of one way or another online is as close as I can figure to pissing in a fan blowing back at you. There is so much opinion and not enough measurable advantage to either one.

I chose my method for my reasons....and I'm not looking back at all.

kpt4321

If you have a counterpoint to make, then make it. Telling us "I don't think you're right" doesn't do a damned thing for productivity.

Here are some pictures of race cars:

http://www.importspeed-south.c...4.jpg

http://www.importspeed-south.c...1.jpg

http://www.importspeed-south.c...1.jpg

Those are just the first three pictures of full race cars designed from the ground up with intercoolers and BOV's that I found on Google. You tell me why they ALL have the BOV's mounted AFTER the intercooler.

On the cars without intercoolers (methanol) there was no obvious attempt to put the BOV close to the turbo, in fact, the all seemed to be closed to the throttle body.

BROOD

Chill out I never said "you are not right" but rather that I did not agree. Get used to it. Your on an open forum where contradicting points of view help think about the ideas.
Sorry, I'm too old to feel that a pissing match is in order with a 18yr old. I've done my time, earned a degree, build my cars, and have made my mistakes.

Besides, I'm not building a race only car or a meth car and I doubt the majority of the people here are doing so either. Street cars is probably the main focus. Like I said it is more important that the BOV is in the system....the difference in "where" would be minimal and difficult to quantify for comparison.
I could probably go find pictures of street car with BOTH bov mounting methods....what would it solve/prove? Probably not much.

If you want to discuss more feel free to IM me.

falcongsr

I have yet to hear any decent explanation as to where to put a BOV and why.

so anyone arguing where to place it probly isn't basing it on any facts, cause i havent seen any advantages to putting it anywhere specific.

kpt4321

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by falconGSR &raquo;</TD></TR><TR><TD CLASS="quote">I i havent seen any advantages to putting it anywhere specific.
</TD></TR></TABLE>

Read my post.

falcongsr

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kpt4321 &raquo;</TD></TR><TR><TD CLASS="quote">

Read my post.
</TD></TR></TABLE>

ok fine thats a valid theory. not putting it where you said has what consequence exactly?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by kpt4321 &raquo;</TD></TR><TR><TD CLASS="quote">If the BOV is near the turbo outlet, then the air has to hit the throttle body, surge, and then you have to hope that all of the surge waves get caught by the BOV on the first pass and don't hit the compressor.
</TD></TR></TABLE>

hope. you used the word hope. surge waves? we're dealing with a low frequency damping system here. this isn't rocket science.

i still maintain there isn't and valid reason to put it one place or another. show me a case where BOV placement caused a problem.

i am willing to bet that manufacturers that do factory turbos with BOV's place the BOV in the location for packaging advantages and to minimize routing of vacuum lines etc. remember they're building 10-20,000 cars. so they'll make compromises on things like BOV location to save 20 cents per car on vacuum hose.

kpt4321

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BROOD &raquo;</TD></TR><TR><TD CLASS="quote">Chill out I never said "you are not right" but rather that I did not agree. Get used to it. Your on an open forum where contradicting points of view help think about the ideas.
Sorry, I'm too old to feel that a pissing match is in order with a 18yr old. I've done my time, earned a degree, build my cars, and have made my mistakes.

Besides, I'm not building a race only car or a meth car and I doubt the majority of the people here are doing so either. Street cars is probably the main focus. Like I said it is more important that the BOV is in the system....the difference in "where" would be minimal and difficult to quantify for comparison.
I could probably go find pictures of street car with BOTH bov mounting methods....what would it solve/prove? Probably not much.

If you want to discuss more feel free to IM me. </TD></TR></TABLE>

I'm not sure where you're going with this. Not once did I try to start a "pissing match," I just stated outright what I knew, and then I found some pictures which backed up my thoughts.

I agree that it probably doesn't matter where you put it on a street car. However, the thread was specificially asking where was best, and not only that, but the location was the point on which you and I disagreed, and thus I looked into it further.

I gave examples of street cars earlier, and you said that street cars weren't good examples due to all the other things that are taken into consideration when a street car is designed. I certainly agree with this, which is why I went and found pictures of the cars that would be the best example, race cars. It had nothing to do with building a race car, it was just an example of where the "pros" put it.

Please don't judge me because of my age, although I know it is easy. While stereotypes may be true, I would much prefer to be judged by what I do and what I say. If you decide those things are not favorable, then I'm sorry.

BROOD

I was not using age as a put down. I appologize if you felt it was in that way. Different opionons and theories are not bad things at all.

Falcon GSR "i am willing to bet that manufacturers that do factory turbos with BOV's place the BOV in the location for packaging advantages and to minimize routing of vacuum lines etc. remember they're building 10-20,000 cars. so they'll make compromises on things like BOV location to save 20 cents per car on vacuum hose."
It still floors me that this is so prevalent in oem auto manufacturing/design, and I have been in the middle of it for some time now. It kinda took the ohh and ahh's out of working around a engine design division. But at least everything has turbos around here....everything

RGAZ

Read maximum boost by Corky Bell. He discussed BOV placement.

My OPINION: Place the BOV as close as possible to the TB plate.

Reason: The column of pressurized air from compressor to TB is moving at high velocity and has some mass. When the TB slaps closed, the column of air smacks the TB and begins to travel backwards. It is best to catch this wave as soon as it begins to travel backwards and there should be a pressure gradient in the column that allows the BOV to see the HIGHEST pressure and the compressor to see the LOWEST pressure all the while maintaining a minimal increase in pressure in the column of air. Thus, closest to TB and most direct run to ATM.

Now, in reality, there is no appreciable negative to putting it closer to the turbo. the only MINOR positive is the that you can vent the air from turbo and IC at the same time. The negative is that the column of air in the charge piping after the BOV will be turbulent (and moving towards the compressor) when the BOV closes again. Thus, you must expend compressor energy to stop the air or "re-fill" the charge piping from BOV to TB. Thus, a slight (unnoticable) lag added.

Feel free to argue if you want, its a free net. But that is my reasoning and my opinion.

Later,
Randy aka RGAZ