Noob BOV question

[str33tpr3p]

I know its a noob question to ask this but ive been looking around and reading lots but i cant seem to find the better answer.. What side to mount a BOV onto on my sr20det blacktop. The pros and cons between hot pipe and cold pipe, also which one is which i know its a noob question but still. Also if its better to run it recirc or atmospherically.

Thanks

[tabasco122]

Hot is between the turbo and inter cooler, cold is between the inter cooler and throttle body.

[Edwin562]

You haven’t searched hard enough; On MAF based turbo-charged recirculating the BOV is strongly recommended. Basic turbo 101, Best placement for the BOV would be 6” away from the TB on the cold pipe. A lot of Sr owners do place the bov on the hot pipe but its all in the owner’s preference.

[str33tpr3p]

i really appreciate it guys. Helps me out alot, well thats what i figured was on the cold side, why do many owners place on hot pipe? is there a major difference between them both?

[4x4le]

If they are going to recirc its closer to the turbo inelt. If its on the cold pipe the air dont have to change directions making it work better though.

[Kingtal0n]

The best place for the bypass is generally as close to the turbocharger as possible. Recirculated on a maf vehicle for best performance.

[KiLLeR2001]

Hot side for me. That way you don't have to run a long ass hose back over to the intake pipe after MAF for recirculation.

[4x4le]

The best place for the bypass is generally as close to the turbocharger as possible. Recirculated on a maf vehicle for best performance.

2 people already said hotside, close to the throttle body and gave reasons why. You decide to go against this with another one of your ignorant posts and give no explanation why.

My car ran good with it on the cold side first, not recirculated, and then i moved it to the hotside, not recirculated, and it does even better. I didnt have any problems with it dipping too low below idle when off throttle or wanting to die ever, the gain i noticed when switching sides was when i would go on and off throttle back to on the responce was much better because the air didnt change directions and the turbo didnt have to refill as much of the volume of the piping and intercooler with pressure again.

People always seem to ASSume that all maf cars are pullthrough. There is no need in recirculating a blow through setup. If you have a blow through setup its pointless unless you put the maf before the bov. Most of the time the maf is on the coldside so many people put the bov on the hotside. You may have room on the cold pipe before the maf, you could put it on the cold tank on the intercooler ect.

Saying it needs to be as close to the turbi as possible is just an uneducated answer. Break that down for me, why exactly would putting as close as possible to the turbo be best?
Dont say because thats whats making the boost, because when the throttle is shut its no longer being driven enough by the exhaust to make boost. What your trying to blow off is the pressure thats (not quite so) trapped in the pipes, without the bov the compressor would be the easiest way out and thats bad because air is reversing flow and your forcing the turbo past its surge line. Putting the bov close to the compressor only helps one of those problems, and having it real close to the compressor is actually asking for some surge when you come back on throttle because your rushing air tword the compressor and when you open the throttle your closing the bov before the turbo has a chance to become effecient again.

[Kingtal0n]

2 people already said hotside, close to the throttle body and gave reasons why. You decide to go against this with another one of your ignorant posts and give no explanation why.

My car ran good with it on the cold side first, not recirculated, and then i moved it to the hotside, not recirculated, and it does even better. I didnt have any problems with it dipping too low below idle when off throttle or wanting to die ever, the gain i noticed when switching sides was when i would go on and off throttle back to on the responce was much better because the air didnt change directions and the turbo didnt have to refill as much of the volume of the piping and intercooler with pressure again.

People always seem to ASSume that all maf cars are pullthrough. There is no need in recirculating a blow through setup. If you have a blow through setup its pointless unless you put the maf before the bov. Most of the time the maf is on the coldside so many people put the bov on the hotside. You may have room on the cold pipe before the maf, you could put it on the cold tank on the intercooler ect.

Saying it needs to be as close to the turbi as possible is just an uneducated answer. Break that down for me, why exactly would putting as close as possible to the turbo be best?
Dont say because thats whats making the boost, because when the throttle is shut its no longer being driven enough by the exhaust to make boost. What your trying to blow off is the pressure thats (not quite so) trapped in the pipes, without the bov the compressor would be the easiest way out and thats bad because air is reversing flow and your forcing the turbo past its surge line. Putting the bov close to the compressor only helps one of those problems, and having it real close to the compressor is actually asking for some surge when you come back on throttle because your rushing air tword the compressor and when you open the throttle your closing the bov before the turbo has a chance to become effecient again.

I didnt give a reason why because i like to keep posts short when possible. If someone happens to ask me a question, "WHY", I will HAPPILY give reasons and data to support my words. I would never supply information for which I have done no research... All of my posts and advices are given from personal experience and/or proper research.

2 people already said hotside, close to the throttle body and gave reasons why. You decide to go against this with another one of your ignorant posts and give no explanation why.

None of the "reasons why" given so far are backed by any actual mathematical data... only speculation and assumptions. Your "reason why":
My car ran good
speculation, no data. Did you even check the differences in visible plug characteristics over the course of varied series of driving styles?

I didnt have any problems with it dipping too low
Not everybody uses the same bypass valve as you and so experiences with this will vary- your "reason" here is a blanket statement that assumes every individual has the same exact engine/parts are you do. ex. Some bypass will hang open during vacuum situations (such as a greddy type-s that is set "loose") and the idle will dip and the car will not run right, not even at idle, as that particular bypass will hang open during idle if set loose.


There is no need in recirculating a blow through setup.

I do not recommend blow-through setups for our community due to the complexity involved with turbocharged vehicles. I believe that if Nissan felt the engine would be best served with a MAF after the turbocharger- it would be there.


Saying it needs to be as close to the turbi as possible is just an uneducated answer. Break that down for me, why exactly would putting as close as possible to the turbo be best?

Ok, Excellent question, and here is a question in response to get you thinking:
What is the purpose of a bypass valve?


Answer: Protect the compressor wheel from unnecessary wear and tear.

How can we best achieve this?
Short answer: Evacuate the plumbing as fast as possible during a potential "surge" situation.

Long answer: Pressure in the plumbing above atmospheric will drive the net flow of molecules in the path of least resistance. When the engine is presenting such a path, the molecules flow into the engine and are used to drive the process of combustion. When the throttle body shuts the engine is no longer an opportunity for easy escape- instead the compressor wheel becomes the path of least resistance. Air molecules that escape past the compressor wheel cause a situation known as "Surge". The invention of the bypass valve was intended to provide a solution to this situation. When the throttle body shuts, hopefully the bypass will open, and air molecules will be presented with a better path of least resistance- one that will not potentially damage the compressor wheel.

-The speed of the evacuation depends upon what?
the size of the hole that the bypass presents, the size of the plumbing, the pressure ratio inside the plumbing above atmospheric, the kinetic energy of the molecules themselves, and more. We can speed the process by making the hole bigger, right? more molecules can fit through a larger hole at identical pressures. What else can we do? Move the hole closer to the compressor? Imagine we move the bypass farther and farther from the compressor, and make a chart of the pressure in the plumbing after the bypass opens. As you move the bypass an infinite distance from the compressor, you will find that the pressure drop occurs more and more slowly at the compressor, simply because there are more and more molecules of air that need to be evacuated on the side of the compressor that eventually will result with a drop in pressure.

[Croustibat]

Stop your masterbating party, any place is ok as long as you recirc it.

The op is not going to run 4 bar boost so why even bother ...

That is one of the most obvious troll on boosted engines BBS, wake up guys ...

[4x4le]

when the throttle is shut its no longer being driven enough by the exhaust to make boost. What your trying to blow off is the pressure thats (not quite so) trapped in the pipes, without the bov the compressor would be the easiest way out and thats bad because air is reversing flow and your forcing the turbo past its surge line. Putting the bov close to the compressor only helps one of those problems, and having it real close to the compressor is actually asking for some surge when you come back on throttle because your rushing air tword the compressor and when you open the throttle your closing the bov before the turbo has a chance to become effecient again.

This still super seeds your explanation.

drive the net flow of molecules
give me a break, air is air. Volume or pressure is fine, no need to get down to molecules, atoms, or what gasses are making up the air, your just trying to sound smart to help your case.

When the throttle body shuts the engine is no longer an opportunity for easy escape- instead the compressor wheel becomes the path of least resistance. Air molecules that escape past the compressor wheel cause a situation known as "Surge"

once again, air would have sufficed. No one would have got confused at all if you just said air. Anyways if you look at the post of mine that I quoted I bolded a statement that you pretty much just re worded to act like you are telling me something.

the pressure ratio inside the plumbing above atmospheric

once again trying to use words to throw other off to make yourself sound smart. You do this every time I disagree with you on something.
Pressure ratio is a figure you get from pressure and atmosphere pressure. Saying pressure ratio above atmospheric is redundant and incorrect.

Move the hole closer to the compressor?
Why, you have said it yourself that it is the path of easiest evacuation of air (assuming no bov). This implies, and it also is a fact that without the exhaust driving the turbine the compressor does not have the energy inputted into it in order to compress air. The compressor is not what is in need of relief, its that air that it ALREADY compressed and sent into your pipes before you shut the throttle.

Imagine we move the bypass farther and farther from the compressor, and make a chart of the pressure in the plumbing after the bypass opens. As you move the bypass an infinite distance from the compressor, you will find that the pressure drop occurs more and more slowly at the compressor, simply because there are more and more molecules of air that need to be evacuated on the side of the compressor that eventually will result with a drop in pressure.

Physics owns you. Your wrong.
Lets humor your hypothetical situation of a very long distance of pipe. One the pipe being long will help cool the air and that is why the pressure drops the further it gets away. It will be just as if not more dense than the higher pressure air closer to the compressor. Lets also keep in mind the air is flowing in one direction, and that is away from the compressor. Hot dense air also wants to flow to cold less dense areas. Putting a bov at the end of your really long pipe will still out perform the bov being near the compressor. It will make the lower pressure air at the end of your really long pipe less dense and cool quick as it moves through the bov. It will be making a very easy path for the hot dense air to move to and it will continue flowing in the correct direction. The compressor is not being driven enough to overboost or go past the surge line.

Now compressor surge at closed throttle really isnt THAT big of a deal because there is such little load on the turbine or compressor, the surge that is terrible is while your on the throttle. Putting the bov close to the compressor is actually asking for this kind of surge. When you put it there your asking all of that air to change its direction of flow. During a quick shift it haults, flows backwords, then when you quickly get back on the throttle the the bov closes and that air has to change direction fast. The compressor takes back off quick too and the air actually slams into each other creating a pressure spike that is likely to put your compressor past the surge line.






Something you may not know, im not just talking about what works for me. I tune cars professionally. I have seen many examples of many different setups. I have never needed to recirculate the bov on a pull through maf car. If your able to tell the computer you dont need fuel over X rpm if the throttle is closed there isnt any more of a rich condition than you get from slamming the throttle shut on a N/A car. Where you tell the ecu you do need some fuel even with the throttle shut you tell the iacv to be ready to modulate its throttle and to not let the rpms dip. Its really that simple.

Also with your comment about blow through mafs and nissan would have done it if they thought it was needed or whatever. Fuck what nissan thinks really. If that were the mentality we wouldnt modify the cars at all.
The reason nissan didnt go blow through is for a few reasons.
The maf requires more frequent cleanings, People wouldnt want to do this.
It was cheaper for them to be made of plastic, which wont last as long holding pressure as they will just pulling in air.

[Kingtal0n]

I share a common interest in the love of high performance vehicles, and i seek only to improve life for everybody that would share this interest. My posts are loaded with love for safe, fun vehicles, that is my only intention.

We cannot move the plumbing of the compressor an Infinite Distance from it, that would be silly. In the real world, there is no static number of air molecules in the plumbing, the engine is still breathing, and the compressor wheel is still spinning. The situation is dramatically dynamic, such that it would take hours of accumulation of exact numerical data to perfect actual predictions of current running engine characteristics. When you are not touching the gas pedal, and the engine is decelerating, there is a much different situation inside the plumbing when compared to full throttle high boost. My example is only intended to give a snapshot of one possible situation, a most probable one as I deemed fit to describe the relationship between the distance of the bypass to the compressor- which relates to the original question: where to install the bypass?

Obviously, a real world example should be used for two situations to describe the bounding of this relationship. The first would be a real world bit of plumbing. A tire is a great example of a bit of plumbing, for it does contain AIR molecules, and they are trapped at some PRESSURE above our atmospheric, if the tire is intended to support a typical vehicle. Let us compare the SIZE of the tire to the SIZE of the plumbing- that is, bigger tires hold more air molecules at similar pressure/temperatures than smaller tires, and as compared to the NON-REAL WORLD EXAMPLE of Standard Pressure and Temperature: 22.4Liters, exactly, for an ideal gas, at Standard Temperature and Pressure.

Now put a hole in your tire. You may find through experience that a LARGER HOLE will drain the air quicker than a SMALLER HOLE. Simply, because more air molecules can fit through a larger hole during one such recorded slice of time as integrated by a function of time that describes the hole's appearance in the tire! For instance, if the hole is created slowly, then at very first instant there will only be very few air molecules escaping to our atmosphere, Followed by more as the hole gets larger and larger. And in the REAL WORLD, there is no HOLE that can just appear instantly, so it is necessary then to not only describe the size of the hole but also it's very appearance, shape, and characteristics (Is it flat or does it obstruct the exit of air molecules from the plumbing because of it's shape or design?)

Clearly, much goes into a real world example if it is to be used. So far we have agreed that the size of the hole, the shape, the way it is revealed, the temperature and resulting pressure of the gas itself, the pressure of the atmosphere into which the gas seeks to escape, even many physical underestimated and unforeseen values that play incidental roles such as the resulting deformation of the tire or plumbing due to the pressure, seemingly insignificant unrelated calculations all play important roles in the final real world result, which is why they have things like STP- real world example are often tedious to calculate with exactly accuracy. Often it is favorable to call on theoretical "perfect" examples and relate these to the real world problem in question.

In my perfect example the air pressure and molecules begin as a static time slice in which a hole appears infinitely fast, suddenly, presenting the static number of air molecules an exit the plumbing. If you merely chart the resulting decline in pressure of a tire you would find that the pressure appears to drop evenly within the tire, since gas molecules are always in constant motion at STP they are moving to take the place quickly of any escaping molecules and providing unique, constant pressure to the entire tire, even if such a pressure is in decline.

Realizing this would require a further explanation I induced the improbable situation of the bypass moving an infinite distance from the compressor. If you were to increase the size of the tire suddenly, the pressure would simply drop because no new air molecules are entering the tire. This is not the case with our real world example of the plumbing after a turbocharger: New air molecules are constantly being moved into the plumbing not only by our atmosphere (due to the demand of the engine) but also because of the compressor itself, which is probably (hopefully) spinning and applying a vector of magnitude M force to specific air molecules within it's grasp, and all of the air molecules downstream of the compressor are supposed to experience some of this force with the end result of moving more of them (QUANTITY of air molecules, which is directly related to horsepower output) into the engine.
We are once again dealing with an infinite number of calculations, some of the most "perfect" of which are assumed and given in the form of a compressor map, which you may have heard of.

The compressor map, among many thing, attempts to explain one relationship between impeller speed, temperature, and capability where regarding a situation known as "Surge" in which the compressor can no longer operate effectively do one of it's designated jobs, which happens only to be called for during certain situations. A compressor is not always applying enough force to air molecules that it will effectively compact them and create a pressure- despite the impeller speed being high enough to do so. Also, the compressor maps do not surge at exactly "XX,XXXrpm" The calculations used to derive those numbers are also "perfect examples" like the one I created because real world examples would require much more data-

So static assumptions with this "perfect" compressor assume that speeds of the impeller that would result in pressure ratios (as deemed by the engine's demand for air molecules, which is affected by the throttle body (also called air valve)) in which the compressor wheel would experience a potentially degrading/damaging situation, are achieved. What is the point of considering situations that would not damage the compressor wheel, such as idle? At the speed of the impeller during idle there is not a sufficient situation to damage the compressor wheel so operation of a bypass would not be as important- HOWEVER, that does not mean that a bypass valve could not function during idle! Nissan seems to feel, that during idle, the bypass valve should be open! Excess air molecules entering the plumbing should be allowed to bypass the compressor during their exit from the plumbing- they should return to the inlet where the pressure is atmospheric! Excess pressure there will retard the entry of atmospheric air molecules, and it will also help keep the compressor spinning. If air is forced to exit via the compressor it will apply a force to the compressor wheel opposite to that of the nature of the turbocharger's design- the EXACT situation that can potentially DAMAGE the compressor wheel when it happens during other instances.

Regardless of whether the bypass functions at idle, the main concern for most of us is preserving the life of our compressor wheel with a bypass valve the best we can. My example uses the perfect bypass, one that opens impossibly instantly, with a reasonable size hole. Reasonable of course, with respect to the situation. it would not due to have a hole the size of a peanut open up during a transition shift between 1st and 2nd gear in my car. The air in the plumbing could not expect to effectively exit quick enough due to the size of the hole.

Using a Silvia, Nissan, SR20DET Engine, OEM equipment.
Real world example "impossible" variables being considered:
Proper plumbing diameter(1.8"-2.5"), proper bypass hole diameter/position(1
-3"), proper engine displacement(1.5-3.0L), proper compressor(20lb/min +/- 50lb/min compressor), etc... with all values being subject to appropriate disagreement, for instance some of you may feel that a 100/lb/min compressor is also proper, and that would be an appropriate argument, whereas a 5lb/min compressor is simply ridiculous and would not be appropriate. So in the end even my "proper, perfect" experimental settings are subject to change, they are only set to mostly agreeable values, the same way STP is set around a general, agreeable atmospheric pressure-




Now, Returning to this point knowing all of this:
In my perfect example the air pressure and molecules begin as a static time slice in which a hole appears infinitely fast, suddenly, presenting the static number of air molecules an exit the plumbing. If you merely chart the resulting decline in pressure of a tire you would find that the pressure appears to drop evenly within the tire, since gas molecules are always in constant motion at STP they are moving to take the place quickly of any escaping molecules and providing unique, constant pressure to the entire tire, even if such a pressure is in decline.

If our real world plumbing was just like a tire, then it would not matter where you put the bypass valve, since a tire experiences a force from the air molecules contained within it evenly. You could put it anywhere after the compressor and before the throttle body: hotpipe, coldpipe, doesnt make a difference.

So now I am going to add a new variable to our tire: We are Filling it, and Draining it, at the same exact time. If the same exact numbers of air molecules is entering the tire AND leaving the tire, the number of air molecules in the tire will remain constant, and the pressure will neither increase nor decrease over time. Now let us consider our situation in detail:


In order for air to be moving into the tire, there must be a greater pressure outside the tire. Likewise, in order for air to EXIT the tire, there must also be a lower pressure outside the tire. Let us position a compressor at one hole, and a atmosphere at the other hole to meet these conditions. If the pressure in the tire is to rise, the net movement of air molecules going into the tire will be greater than the number of molecules that is exiting the tire. Once the pressure on both sides of the entry is the same, the pressure in the tire stops increasing, but air molecules are still moving through the hole. That is, air molecules are still moving through the hole but an equal number of them is both exiting and entering the tire, so the pressure remains constant. Remember that the air molecules are in constant motion! The inflation of a tire is due to this very motion- the combined magnitude of the forces of all the collisions of air molecules with the insides of the tire is what maintains the shape of the tire and keeps it from collapsing!

Now, I present two situations bearing the application of this knowledge:
If the entry of the air molecules into the tire is positioned very close to the exit, then the pressure immediately near the entry point and exit point for air molecules will be higher than the pressure on the 180* opposite side of the tire.

If we did position the exit hole on that 180* opposite side, it will have the lowest pressure of the entire (symmetric circle) tire, and because of this fact, it will have fewer air molecules exiting the tire when compared to the exit that is placed directly near the entry point for air molecules. It is for this reason that I will recommend placing the bypass valve as close as possible to the entry point, the compressor wheel, for air molecules that would seek to induce a pressure in the system.

/thread

[4x4le]

Your right, it will function on either side. All i tried to explain is how it works better on the cold side due to the fact that air flows toward the throttle body and the compressor is done creating pressure the instant the throttle is released. It is spinning fast enough to create pressure but it does not have anything driving it. That is what causes surge, the turbine not powering the compressor enough to hold in the pressure its creating in.

Your analegy with tires dont work because they are round, the air is not super heated, and then cooled resulting in a pressure drop, which brings me to my next point, the air is dencer and at a lower pressure on the cold side. Your bov can flow more air "molecules" (thanks for even bringing that word into this, i never would have thought to use it against you) out in less time of being open.

[KiLLeR2001]

Whenever there are debates like this I think to myself. "How did Nissan set it up originally?"

Answer: Hot side.

I think the closer to the intercooler on the hot side the better.

[4x4le]

maf vs map: everyone should run maf's
wheels: everyone should run 15x6.5's or 16x7's
no more twin disk clutches, nissan had it right with singles
vlsd vs clsd: oem is better, even if it dont work for long
Paper headgasket or mls: paper
cast pistons or forged: cast
electronic boost controller or just hook up the wastegate: just hook up the wastegate
front mount or sidemount: sidemount
cat converter and quiet muffler with crush bent pipes, or free flowing exhaust: restrictive
gauges that monitor things: dummy lights are just fine
short throw shifter: slop is better
Intercooler pipe material: everyone should use plastic
s15 front end on s14's? Nope, nissan wanted s14 front ends on them
z32/r32 brakes on s13/s14? Nope, if nissan thought we would ever need them they would have gave them to us.
Oil cooler: we would have one if we needed one
Coilovers or struts/springs: strut/spring combos, ride is better and they are cheaper


How did nissan set it up originally? In a way that was cheap to produce, easy to produce, comfortable to drive ect.

The t25 is so little there is probably little difference what side its on. The piping and intercooler is so small as well. Either side will WORK, but if you understand the physics of compressed air flow, at different temperatures you will understand the cold side makes more since.

[AdamR]

This thread has been lulzy. The psuedo-scientific posts killed me. It's funny how nobody on this forum ever listens to people who actually know what they are talking about.
A basic understanding of physics would tell you the cold side is better.

[4x4le]

Yea and I just found this on another forum. Says almost exactly what I said
I especially like that part that I bolded
This is one of those topics that's always up for debate, so you'll have to read some peoples opinions and form your own from there.

The BOV being mounted close to the throttle body makes the most sense to me. All that pressurized air is moving very fast through the intercooler piping, then the throttle plate slams shut. If the BOV is closer to the turbo and on the hot side, the air has to completely stop and reverse direction to exit the valve. If the BOV is closer to the throttle on the cold side, the air can keep flowing forward through the pipes and exit the valve just before the throttle.

On top of that, if the BOV is on the hot side and recirculated, you're venting hot air back into the intake.


Also to answer Killers question about what side did nissan put it? Depends on what car, they have done it both ways actually. Probably which ever side the coin landed on.

[Walperstyle]

Hilarious in here.

An intercooler will have about a 1psi pressure drop. (on average, all depends on a lot of factors). That said, a MAP sensor in the intake plenum will be able to detect this and correct accordingly what kind of pressures your intake is seeing.

that said...

I can't speak for everyone, but this is why some of us go stand-alone and MAP. Either way, its not a big deal, and you probably won't notice much difference how you plumb your BOV. Either way, cold side for me, mostly because buddies in the industry have been doing that.

[KiLLeR2001]

On top of that, if the BOV is on the hot side and recirculated, you're venting hot air back into the intake.


Also to answer Killers question about what side did nissan put it? Depends on what car, they have done it both ways actually. Probably which ever side the coin landed on.

Ah yes, recirculating warmer air back to a turbo which gets over 1000F that's going to be cooled by the intercooler anyways.

[4x4le]

Yes, everything makes the most minimal difference. Every argument anyone can make including myself is minor when it comes to this subject. So all we can do is weigh the pros and cons and look at how everything works and flows. Op asked for pros and cons.

"your cons dont matter" dont work, especially when the the pros for having it on the hot pipe actually dont work.

If you have the choice to put it on the cold pipe, put it on the cold pipe. If you already have it on the hot pipe dont loose sleep about it. I had one on the hot pipe for a long time. After tuning some cars with them on the cold pipe and noticing I liked how much easier it was to tune for atmospheric bov, and noticed throttle responce on and off throttle was better I changed mine to the cold side and I noticed a difference instantly. I never gave it much thought before then but it made me think out what was happening. It is best to have it on the cold side.

If you dont believe me,
molecules, kenitic energy, tires, holes, visible plug characteristics,

[AdamR]

Ah yes, recirculating warmer air back to a turbo which gets over 1000F that's going to be cooled by the intercooler anyways.

This old argument. I suppose a cold air intake doesn't do any good on a turbocharged car?
But what 4x4le said is right, either side will work, but the best location is as close to the throttle body as possible.

[Kingtal0n]

I understand there are many points of view;
Another reasoning for the "hot side" from the point of view of maximum horsepower as opposed to protecting the compressor wheel:

The main purpose of an intercooler is to remove heat from the air, right?
Where does the heat go?

Well, it is absorbed by the aluminum material of the intercooler, first, then hopefully distributed to the atmosphere and lost.

So, if heat is absorbed by the intercooler, as air is passing through the intercooler, then more air flowing through the intercooler would make the intercooler hotter, right?

So, if you are going to discharge air from your plumbing, where will you place your blow-off valve:

A: Before the intercooler, so that the intercooler does not absorb the heat from the air that is simply being discharged.
OR
B: After the intercooler, where the heat has been absorbed by the intercooler, increasing the temperature of the intercooler.

You will find that a bypass valve on the hot-side will reduce intercooler temperatures, and therefore, reduce Cold-Side Temperature, which is the point of using an intercooler to begin with. Why cool air that is going to be discharged?

[AdamR]

^ Just stop.

[Kingtal0n]

^ Just stop.

Stop what? Stop making reasonable observations? Stop having an intelligent discussion? Stop using Zilvia.net for what it is designed?


I am only helping us see both sides of the issue. I, for one, could not care where you put YOUR bov- I know where MINE is. So far I have given several very good reasons to use the bov on the HotSide- Before the intercooler. And I have YET to see ONE good reason to install it on the COLD side.

I have ever more good reasons to use it on the hotside, but I am saving them for when my previous good reasons are shot down.
There is even math, diagrams, pictures and personal experiences to share. So bring it on, the proper discussion without personal attacks.
Use the scientific method.

[AdamR]

If you are not seeing one good reason, read the thread again.
You are invoking science obviously far beyond your comprehension.
When the throttle is shut, the turbo continues spinning at a speed that is creating positive pressure. IF your valve is right after the turbo, you have pressurized air rushing from two different directions (throttle plate and turbo) rushing to get out the one valve. This effect may be relatively minor, but the main reason is not.
When your pressurized air has to turn around to get out, it induces lag when applying throttle again, because it then has to reverse again.
With a throttle body mounted valve, the turbo can keep spinning, pushing air through the piping until the valve closes and it can resume building boost.

If a .1 degree difference is more significant that that, you need to rethink your core design or duct It better.

[4x4le]

cant argue with stupid. cant make the blind see. cant make the deaf listen

[cotbu]

cant argue with stupid. cant make the blind see. cant make the deaf listen
Not True!
I heard the formula was unicorn blood and the sweat of Chuck Norris!

[KiLLeR2001]

Alright, I've read enough bullshit here. Time to lay down the facts.

We all can agree Garrett is the leader in turbocharged systems and they have done extensive research in the field...

Garrett Recommends the BOV to be mounted close to the turbo.

"MAF (Mass Air Flow) sensor uses a recirculation (bypass) valve for best drivability.
* Connect signal line to manifold source
* Position valve close to the turbo outlet for best performance (if valve can handle high temp).
* Surge can occur if valve and/or outlet plumbing are restrictive."

You can view this document here... http://www.turbobygarrett.com/turbobygarrett/sites/default/files/PDF/Garrett_Turbo_System_Optimization.pdf

[Kingtal0n]

Alright, I've read enough bullshit here. Time to lay down the facts.

We all can agree Garrett is the leader in turbocharged systems and they have done extensive research in the field...
Garrett Recommends the BOV to be mounted close to the turbo.

"MAF (Mass Air Flow) sensor uses a recirculation (bypass) valve for best drivability.
* Connect signal line to manifold source
* Position valve close to the turbo outlet for best performance (if valve can handle high temp).
* Surge can occur if valve and/or outlet plumbing are restrictive."

You can view this document here... http://www.turbobygarrett.com/turbobygarrett/sites/default/files/PDF/Garrett_Turbo_System_Optimization.pdf

You spoil all my fun :D

You guys are welcome to stay and ask questions and learn about air molecules if you wish. FWIW, there is no significant "reversing" of air when the throttle body shuts... Just because the air valve is closed does not mean the engine stops breathing all together.
Even an engine at idle requires a significant quantity of... thats right: Air molecules.

[AdamR]

If you read that Garrett paper, it says that on a MAP system to put it close to the throttle body. Ask questions from an internet physics professor? No thanks, I have actual engineering classes to get back to.

[4x4le]

Alright, I've read enough bullshit here. Time to lay down the facts.

Ok, so just because you cant understand what I have said its not fact? 4 sentences from Garret is easier for you to understand I guess.


We all can agree Garrett is the leader in turbocharged systems and they have done extensive research in the field...


They are laying down blanket information. Something that will work no matter what. Something they could get out in 4 sentences. They make turbos, not ecus, not tuning, they make turbos and rely on the manufacturers of cars to make the car work with the turbo. They watched what car companies that use mafs commonly do and just repeated it.

Your saying I havent done extensive research? Your discounting the amount of cars I have had my hands in. Your trying to act smarter than someone that can think for themselves just because you have followed old past practices and read a 4 sentence guide for dummies put out by garrett.


You can view this document here... http://www.turbobygarrett.com/turbobygarrett/sites/default/files/PDF/Garrett_Turbo_System_Optimization.pdf

Read it. Funny you took out of context the information so you and kingtal0n could stroke each others egos.

Here is what I read
Blow Off Valves (BOV)
Using the proper blow off valve (BOV) affects the system performance. There are two
main types to consider.
MAP (Manifold Absolute Pressure) sensor uses either a vent-toatmosphere
valve or a recirculation valve.
- Connect signal line to manifold source
- Surge can occur if spring rate is too stiff
MAF (Mass Air Flow) sensor uses a recirculation (bypass) valve for
best drivability.
- Connect signal line to manifold source
- Position valve close to the turbo outlet for best performance
(if valve can handle high temp).
- Surge can occur if valve and/or outlet plumbing are restrictive.

They said there are 2 things to consider. You left out the information about map based cars. If it were crucial to the turbos performance or life they would have mentioned under map cars that it needs to be put close to the compressor outlet as well, but they didnt.

Now under the maf based cars it was mentioned that it needed to be as close to the compressor outlet as possible. The reason for this is because the turbo outlet is close to the compressor inlet right? The shorter the distance for recirculation the better, if your going to be recirculating, otherwise its a waste to even bother recirculating.
As a matter of fact my first post in this thread mentions this point and you try to come back this much later to use a point I made (while thinking for myself) quoting something from garrett in order to somehow tell me Im wrong? Your going to have to step your game up if you want to argue with me.
If they are going to recirc its closer to the turbo inelt.
Wait, you also said the same thing earlier on, and gave the exact same reason. And that was not disputed
Hot side for me. That way you don't have to run a long ass hose back over to the intake pipe after MAF for recirculation.

What you and garret are not taking into consideration is there is more than 1 type of ecu, and more than 1 method of tuning. If you are able to tell the ecu that when the throttle is shutting fast or shut, no fuel is needed over X rpm then recirculating is more of a determent to your turbo system than a benefit. Some people dont know how to tune or their ecu is not capable of it so they recirc (no huge deal).


You spoil all my fun :D


Nope, and your IQ is lower than I predicted if you think a moot point that was intentionally taken out of context that I actually originally brought up in my first post is somehow going to prove me wrong.


You guys are welcome to stay and ask questions and learn about air molecules if you wish.
Even an engine at idle requires a significant quantity of... thats right: Air molecules.
Yea tell me more about how you add the word molecules to the end of very normal words in order to sound smart. I will drink a glass water molecules in case I get thirsty while you do so.


FWIW, there is no significant "reversing" of air when the throttle body shuts... Just because the air valve is closed does not mean the engine stops breathing all together.

Bull. Lets break this down. If you were to run no bov and monitor pressure in your cold pipe when the throttle snaps shut you would see a spike in pressure for a second or 2. With a bov, mounted anywhere you please, lets just put it on the hot pipe, you will see pressure drop instantly.
That pressure, that air IS REVERSING. It is going somewhere else, which is to your bov. Without your bov, even though your engine is consuming some air the pressure will spike, which goes to show that it isnt consuming ENOUGH air for your point to be valid.


there is no significant "reversing" of air when the throttle body shuts...

Lets break this down. First you quote "reversing" like it is just a theory. Well its a fact. If your going to use scientific terms such as molecules and kinetic energy why dont you gain some knowledge about physics before you try to disprove everything there ever ever was about fluid dynamics.

If that pressure isnt going somewhere, the bov isnt doing its job, but if it is going somewhere the air is reversing. If the air is reversing, then its reversing. You say SIGNIFICANT reversing, if that air so much as stops flowing or goes back in the other direction then you are making it harder on your turbo to do its job, your inducing lag in throttle response by now not only having to re pressurize the pipes (which you would have to do anyways) but you have air slamming into each other in different directions making this process slower while creating turbulence which is also counter productive to flow characteristics.

[4x4le]

If you read that Garrett paper, it says that on a MAP system to put it close to the throttle body. Ask questions from an internet physics professor? No thanks, I have actual engineering classes to get back to.


my response took too long. Seems like we had the same thing in mind about destroying scientific fact with failed hypothesis that came 20 years too late.

[KiLLeR2001]

They said there are 2 things to consider. You left out the information about map based cars. If it were crucial to the turbos performance or life they would have mentioned under map cars that it needs to be put close to the compressor outlet as well, but they didnt.


I think you need to re-read the first post of this thread. It was about which side is best for a blacktop SR20DET which I'm sure you are aware is a MAFS-based system. Thus why the hot side is better.

Now if you want to argue whats best for MAP-based systems then go right ahead, I could care less and you would only be preaching to 10% of the population on here. You're better off making a new thread though.

Here's my advice to you:

- Stop wasting your time.
- Stop insulting others intelligence.
- Get off your high horse.

[Kingtal0n]

If you read that Garrett paper, it says that on a MAP system to put it close to the throttle body. Ask questions from an internet physics professor? No thanks, I have actual engineering classes to get back to.

I can read, and it does *not* say that. And if it does, I am sorry, but please quote where it does?


MAP (Manifold Absolute Pressure) sensor uses either a vent-toatmosphere
valve or a recirculation valve.
- Connect signal line to manifold source
- Surge can occur if spring rate is too stiff

I Just don't see it.

[Kingtal0n]

I think you need to re-read the first post of this thread. It was about which side is best for a blacktop SR20DET which I'm sure you are aware is a MAFS-based system. Thus why the hot side is better.

Now if you want to argue whats best for MAP-based systems then go right ahead, I could care less and you would only be preaching to 10% of the population on here. You're better off making a new thread though.

Here's my advice to you:

- Stop wasting your time.
- Stop insulting others intelligence.
- Get off your high horse.

Thank you! Regardless of what he wants to say, it can be SAID without degrading others intellect!
There is NO REASON to Insult someone while trying to make a point if you have a valid discussion.
Unprofessional, Childish.

[CeezS13]

I'm running a MAF based set up on my black top, I set the BOV close to my Throttle body and it dips low sometimes and when I let off throttle it feels like it wants to die then comes back to perfect idle, so the cold side isn't working for me. gonna relocate it to the hot side and see where it goes from there.

[4x4le]

I think you need to re-read the first post of this thread. It was about which side is best for a blacktop SR20DET which I'm sure you are aware is a MAFS-based system. Thus why the hot side is better.

Now if you want to argue whats best for MAP-based systems then go right ahead, I could care less and you would only be preaching to 10% of the population on here. You're better off making a new thread though.

Here's my advice to you:

- Stop wasting your time.
- Stop insulting others intelligence.
- Get off your high horse.

hot only works better IF your recirculating for the reason of shorter recirc pipe. if running a longer pipe across your engine or if your turbo inlet and maf are somewhat close to your cold pipe then cold side is fine there.

Also as I have mentioned, for flow characteristics regardless of it being maf or map cold side is better. With maf there are things you can do with tuning so the maf is not effected by the wasted unmetered air.

Thank you! Regardless of what he wants to say, it can be SAID without degrading others intellect!
There is NO REASON to Insult someone while trying to make a point if you have a valid discussion.
Unprofessional, Childish.

I cannot help it that it hurts your feelings that I point out that your wrong and that you have no clue how to use the scientific terms your using properly.

I'm running a MAF based set up on my black top, I set the BOV close to my Throttle body and it dips low sometimes and when I let off throttle it feels like it wants to die then comes back to perfect idle, so the cold side isn't working for me. gonna relocate it to the hot side and see where it goes from there.

You can either do some more tuning to make it not care about the maf reading on a quick shut of the throttle body, or you can recirculate. Recirculating will help and may mean to put it on the hotpipe, but the hotpipe by itself is not the answer and will not help.

[GhostlyCoupe]

It's probably worth noting that the guys at Nissan are pretty smart fellas and placed the valve at a certain location from the factory.

End thread.

[4x4le]

On different nissans its placed on different sides. Where ever they had room or it was easier for them to recirc it or cheaper or easier for assembly. If you would have read any of this thread you would see that was mentioned.

Its sad you even bring up this point, are people so incapable of thinking for themselves anymore? Is it just ok for you to assume others are smarter than you so to do it the way they did it?

If nissan did everything right we wouldnt bother modifying the cars they made. You have to keep in mine all of the agendas they have, not everything they did was performance based.

And there is no reason to end the thread. Members are having intelligent conversation which is what forums are for. No rules are being broken.
Every point that anyone can think of bringing up about bov location being best on hot pipe can be shot down by me with a scientific approach with the exception of: recirculating makes it easier to pipe, and if there is no room on the cold pipe.

Its very sad that it seems that the majority of the members are unable to comprehend the physics behind it, but just because its unpopular for me to tell the truth does not mean Im incorrect.

[4x4le]

And the only reason the "valve" was placed there and recirculated from the factory is because the factory "valve" is more than just a bov. It is a diverter valve or a recirc valve. It does not seal up at idle like a bov would. Under boost it is prone to leaking unlike a bov, and nissan DID NOT use a proper front mount intercooler, they used a tiny sidemount with plastic tanks that is very prone to heatsoak so running as little hot air through it as possible is beneficial in a stock setup.

I dont know anyone using the factory plastic pipeing and plastic intercooler. Everyone I have seen in person is using larger diameter aluminum or stainless piping, larger front mount intercoolers with aluminum end tanks.
If your going to redesign that system you should look at what else you might have effected and what else may need modified due to that. Now you have allot more air your moving in the wrong direction if your bov is on the hot pipe.

NISSAN did NOT take that into account.

[cotbu]

http://img.tapatalk.com/4a67b061-1887-553c.jpghttp://img.tapatalk.com/4a67b061-1894-2e1f.jpg

These images suggested that the bpv\bov be on the cold side.
These are from the s14 and gtr r32 fsm

Sent from my Highly Tuned Vibrant!!!

[4x4le]

that they are.
And if I had to speculate, its because these engines are making higher hp than the s13 sr, and of a later design. So nissan learned that it was better to put them on the cold side, and they learned that with more air flow that it was of a benefit.

Not too many people waste their time swapping in a sr to just run the stock turbo, they upgrade to something more powerful than the s14/15 t28 as well.

cold side is BEST. But by all means, you other guys can do what you want with your cars. Just dont try to spread false information in order to kill everyones throttle response that may read your post.

[GhostlyCoupe]

On different nissans its placed on different sides. Where ever they had room or it was easier for them to recirc it or cheaper or easier for assembly. If you would have read any of this thread you would see that was mentioned.

Its sad you even bring up this point, are people so incapable of thinking for themselves anymore? Is it just ok for you to assume others are smarter than you so to do it the way they did it?

If nissan did everything right we wouldnt bother modifying the cars they made. You have to keep in mine all of the agendas they have, not everything they did was performance based.

And there is no reason to end the thread. Members are having intelligent conversation which is what forums are for. No rules are being broken.
Every point that anyone can think of bringing up about bov location being best on hot pipe can be shot down by me with a scientific approach with the exception of: recirculating makes it easier to pipe, and if there is no room on the cold pipe.

Its very sad that it seems that the majority of the members are unable to comprehend the physics behind it, but just because its unpopular for me to tell the truth does not mean Im incorrect.

I think it's even more sad that there is always someone who thinks they know better than a company that invested untold millions into designing the car exactly how they did.

Even aftermarket companies that made aftermarket bolt-on kits such as ARC no doubt have many engineers and a lot more knowledge than you do and still chose to use the hot pipe on the S-chassis.

So basically what you are saying is you know better than Nissan, ARC, and Greddy who all placed it on the hot pipe.

[Walperstyle]

^Underground Racing. I've seen BOV's Cold, hot, and on a condenser.

[4x4le]

I think it's even more sad that there is always someone who thinks they know better than a company that invested untold millions into designing the car exactly how they did.

This goes for everyone that modifys any car. Is yours 100% stock? You do know they invested untold millions making it the way they did right? So nothing needs changed.

Even aftermarket companies that made aftermarket bolt-on kits such as ARC no doubt have many engineers and a lot more knowledge than you do and still chose to use the hot pipe on the S-chassis.
So, thats still not a worthwile argument. So a bunch of people do it wrong, and? Just because major companies do something does not mean its BEST, which is still what the question was.


So basically what you are saying is you know better than Nissan, ARC, and Greddy who all placed it on the hot pipe.
First of all, nissan changed to the cold side later on. You fail at reading
2nd
You said that, not me. You do not know who I am, so you have no basis to say that ARC has more knowledge than me.
I have have had my car with the bov on both sides. I have had friends with bovs on both sides. I have tuned tons of cars and I have seen them on both sides. I have made my mind up based on my observations.
I can tell you that I know about this subject better than you. You hear greddy, arc, nissan and just assume they are right. Come up with a real reason that hotside is better. Explain to me how the compressor works and how the low input from the turbine during shut throttle effects the compressor. Then tell me how its better for it to be on the hot side.
Its not. I have listed countless reasons and you and others want to discount that because name brand companies do it differently in their KITS. I guess people buying kits are easy to fool anyways, otherwise they wouldnt be buying KITS.

On my own engine, I have designed a turbo system that does not exist to be purchased in a kit. I cannot wait to get it finished up to have some results on that.
On my last engine I was able to make more power than anyone else has ever been able to make with a 2871r on a sr.
I have tuned a ka24de that was well built to make more power n/a than a stock s13 sr makes.

Do not under estimate what I know or can do. You dont know me from Adam for you to think just because Im not backed by a major company that Im wrong. Also, you dont know how many contacts I actually do have with some major companies, how many other tuning shops Im in contact with constantly.

-----------------------------------------------------------------------

If anyone else really wants to act as Im wrong, think for your self or at least bring some real evidence that its better for it to be on the hot side. I have made plenty of points and all anyone has been able to do so far is say other brands do X or Y. Do some physics, look at it from that point of view. Switch sides and compare results. Asking me to explain why other companies do something that I dont agree with is just a cheap way of trying to set me up. How would I know why they made a less than best decision?

BTW ARC and Greddy have both in the past filed bankruptcy and I never have. Nissan was headed in that direction and Renault merged with them saving their ass.
Maybe you should file bankruptcy it must be smart if greddy, arc and nissan........

[AdamR]

Still so many logical fallacies in arguments here.
I admit i was wrong about the Garrett paper. I may have thought of something else.

Either way, nobody that said the hot side is better has given any good scientific info or data to prove it.