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MBC... Tee'd to BOV!

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I don't get why people tee into the bov line AT ALL, but especially not for a gauge. Thats just silly. You want boost and vac typically, and that will not give vac. You need a manifold source for the most accurate boost and vac. But then again, what do i know. I only listen to all the wisemen and mods on this site that have been doing this shit for years and years.

Edit, running without pvc is also kind of silly but thats a whole new thread.

Teeing it into the bov line...

You guy's are about the third big shop now that has mentioned hooking it up that way.

Both.. Robert and Brian @ FP told me that they tee off of the bov line, as well as Robert from Road Race Engineering, so when you have big shops telling you that, I think I would tend to believe them.

There are so many heated debates about that subject on here it's not even funny. :)



These guys all seem to agree with my opinions, and i bet they have been doing it longer than some wisemen and mods. ;)


Joe
SBR
 
I have had good luck with the FPR line as well, but I prefer leaving that on its own. I would say the FPR line or the P on the TB, anywhere else just seems a bit senseless. And the PCV line is wicked bigger than the other vacuum lines so thats not that practical.



Joe
SBR

If I were to try to tap to the pcv port in the manifold Id try to come up with some kind of threaded fitting or jet that allows it to match the vacuum hoses size. But since Im lazy I will just tap to the FPR as I did on my gst set up, it seemed to be fine there...

staticbrainwash said:
I don't get why people tee into the bov line AT ALL, but especially not for a gauge. Thats just silly. You want boost and vac typically, and that will not give vac. You need a manifold source for the most accurate boost and vac. But then again, what do i know. I only listen to all the wisemen and mods on this site that have been doing this shit for years and years.

Edit, running without pvc is also kind of silly but thats a whole new thread.

Tapping to the bov line isnt my work, as I mentioned I bought the car with it that way, but the owner I bought it from didnt have any issues with it there...

And as for running stock pcv setup, it just causes a boost leak. Most pcvs even new, dont seal high boost pressure no matter how many you buy. Also this lasers engine has some blow by because the catch can collects, and that would just be another reason to make the car smoke if It was left in the intake manifold... A lot of ppl have gone this route and ditched the pcv, and some have came up with check valve which is even better...

http://dsmtuners.com/forums/showthread.php?t=229338&highlight=no+pcv
http://dsmtuners.com/forums/showthread.php?t=242123&highlight=no+pcv

Some says running it like that dirties up the oil, but not much of a change here and I change my oil quite often
but I was considering running the v/c vent line back to the intake arm w/ a fuel filter and leaving the pcv line hanging but this is for a different thread...
 
These guys all seem to agree with my opinions, and i bet they have been doing it longer than some wisemen and mods. ;)


Joe
SBR

Even though those two particular shops seem to be among the most experienced shops in our community, they aren't above making mistakes or being misinformed. I'm not taking sides on this one, I'm just saying that it's not always the best idea to "follow the crowd".
 
"Spouting"? Oh yeah, there's no proof of this if you search.

Compressor surge because of tapping into the bov line. Boost spike. Hope you don't get a boost leak in the system before the mbc either because then you'll overwork the turbo leading to premature failure.

How is any of that good? And how hard is it to search for this? It's been talked about a lot. Look for posts from oldman on this. And how lazy do you have to be to not tap into the compressor outlet elbow or compressor housing. Seriously, i would rather leave my bov line untapped. Safer and there's proof of it.

Don't believe me? Have fun and don't cry to me when you bust something because of it.



Oh I will. My car has run the same MBC off the BOV line since 03. I've never had a problem with surge, flutter, spiking or anything else you mention. Guess I must have a freak. :rolleyes: I never said it was hard to search for, I never bothered since I don't have a problem. I just wanted to know what you're basis was and apparently it's following the crowd, not doing what works for you and your application.
 
So we're lazy? Thats cool. Like it was said, practically every upgrade path, mbc install instruction tells you to tee into the line. Its not lazy dude, its the way its been done I suppose. I'm sorry if you had problems with your car because of teeing into that line...but what is good for one guy's car may not be good for another, especially when its ONE car. And reputable DSM shops tee their bov line.

Not to be a douche, but I'm still waiting for your proof. If its convincing enough, I may seriously consider using my compressor fitting, which I already have tapped. : )
 
Im with marq95gst . I have yet to see any hard proof of one being better than teh other and for the most part, people agree that they have had better luck off the bov line. But at this point its almost like arguing that vanillia ice cream id better than chocolate. Opinions.


Joe
SBR
 
Exactly, which is why i said before, to run how you want. I don't need to show proof for anything, because no one has given proof to me why the bov line is better either. And it's not like it would matter anyway. Everyone just keeps saying "well it works for me". And thats great, try it my way too just for kicks maybe. I've had it both, and i prefer it from as close to the turbo as i can get.

And i didn't mean you're all lazy, i just meant it's easier to tee into the bov than it is to use the compressor outlet or housing. (even though i bet there's even a boost source still there from the stock bcs).

Do what you want. I'll run how things helped me.
 
Exactly, which is why i said before, to run how you want. I don't need to show proof for anything, because no one has given proof to me why the bov line is better either. And it's not like it would matter anyway.

Well i was stating wanting proof mainly in regards to your "it could be deadly comment."




Joe
SBR
 
And i tried to explain about compressor surge from interrupted bov vac, over boosting from running the source from so far along the system, and over boosting then can also be an issue to a motor if too much air goes through unregistered. Now i imagine the motor is the LAST thing that could be a big issue. But i can see this as being a MAJOR issue if things got bad for a turbo.
 
And i tried to explain about compressor surge from interrupted bov vac, over boosting from running the source from so far along the system, and over boosting then can also be an issue to a motor if too much air goes through unregistered. Now i imagine the motor is the LAST thing that could be a big issue. But i can see this as being a MAJOR issue if things got bad for a turbo.


Compressor surge is a condition caused, generally when a car with a turbo has a BOV that fails (or no BOV at all). When the driver slams the throttle plate shut, there is still compressed air in the charge pipe that gets slammed into the compressor wheel, creating a "backspinning" effect.The other way surge can happen is if a compressor wheel is required to move a volume of air far beyond its capacity. A similar situation occurs, except instead of backspinning the pressure generated by the turbo will oscillate. Neither which could be affected by the BOV line being tapped unless you have some SERIOUS vaccuum leaks, and at that point it will be so bad the car would barely run and/or boost. :thumb:


Joe
SBR
 
SBR Joe said:
Compressor surge is a condition caused, generally when a car with a turbo has a BOV that fails (or no BOV at all). When the driver slams the throttle plate shut, there is still compressed air in the charge pipe.The other way surge can happen is if a compressor wheel is required to move a volume of air far beyond its capacity. A similar phenomenon occours, except instead of backspinning the pressure generated by the turbo will oscillate. Neither which could be affected by the BOV line being tapped unless you have some SERIOUS vaccuum leaks, and at that point it will be so bad the car would barely run and/or boost. :thumb:


Joe
SBR








And what hard evidence do you have available to support your statement about any negligible effects when tapping into the BOV vacuum line for an MBC source?
 
And what hard evidence do you have available to support your statement about any negligible effects when tapping into the BOV vacuum line for an MBC source?



The hard evidence i have is derived from me doing this to more cars than i can count, and having pysically tested between the two sources and found more consistently, having better results with a manifold pressure source. The question to be asked is what evedence do you and your comrades have to support the fact that it is not ok to have it this way?



Joe
SBR
 
I had it work wonders on my car. Fixed my crappy bov response, cured my weird boost setting issues, and is much more accurate. All i did was change the boost source. So there's personal experience.
 
I had it work wonders on my car. Fixed my crappy bov response, cured my weird boost setting issues, and is much more accurate. All i did was change the boost source. So there's personal experience.

Well we all know that there is no consistency between dsm's. So what works for you may not be the best for someone else. So theres no real "correct" way to do this, just therioes and opinions...like stated before. Thus this thread is going in circles, and everyone considering either of the two argued methods should try both, and which ever works better for you, then go with it. Point made is it will not "hurt" anything doing it either way.:thumb:


Joe
SBR
 
Er, I'm working with Robert over at RRE to get the engine they built fixed up... asked him about the BOV tee/compressor housing thing, and he said to use the compressor housing nipple if at all possible.
Teeing off the BOV line is the lazy/old way, if you don't *have* a compressor elbow vac fitting, and don't want to take the time to install one. As I understand it, Voodoo put the BOV tee installation into their instructions as not everyone has a compressor fitting, and they didn't want to get people calling in all the time asking about it and bothering them.
Slower wastegate response, slower BOV response, dead turbos come a lot faster when that charge washes back thanks to the slower BOV.. even a little bit will add extra strain on your turbo. Only thing you lose is the quick slam shut of the wastegate under vacuum, but the spring should be more than enough to get things buttoned up, unless you need a new wastegate.

Don't think I'll be listening to SBR for any of my part installs. If you just think about it logically, it's pretty obvious that teeing into the BOV line is a crap way to do it. And if they're pushing this method for wastegates, who knows what'll come out on a more immediately vital part?
 
Er, I'm working with Robert over at RRE to get the engine they built fixed up... asked him about the BOV tee/compressor housing thing, and he said to use the compressor housing nipple if at all possible.
Teeing off the BOV line is the lazy/old way, if you don't *have* a compressor elbow vac fitting, and don't want to take the time to install one. As I understand it, Voodoo put the BOV tee installation into their instructions as not everyone has a compressor fitting, and they didn't want to get people calling in all the time asking about it and bothering them.
Slower wastegate response, slower BOV response, dead turbos come a lot faster when that charge washes back thanks to the slower BOV.. even a little bit will add extra strain on your turbo. Only thing you lose is the quick slam shut of the wastegate under vacuum, but the spring should be more than enough to get things buttoned up, unless you need a new wastegate.

Don't think I'll be listening to SBR for any of my part installs. If you just think about it logically, it's pretty obvious that teeing into the BOV line is a crap way to do it. And if they're pushing this method for wastegates, who knows what'll come out on a more immediately vital part?



Oh well, it works fine for me so ill stick with it, doesnt mean you have to follow. :thumb:


Joe
SBR
 
Er, I'm working with Robert over at RRE to get the engine they built fixed up... asked him about the BOV tee/compressor housing thing, and he said to use the compressor housing nipple if at all possible.
Teeing off the BOV line is the lazy/old way, if you don't *have* a compressor elbow vac fitting, and don't want to take the time to install one. As I understand it, Voodoo put the BOV tee installation into their instructions as not everyone has a compressor fitting, and they didn't want to get people calling in all the time asking about it and bothering them.
Slower wastegate response, slower BOV response, dead turbos come a lot faster when that charge washes back thanks to the slower BOV.. even a little bit will add extra strain on your turbo. Only thing you lose is the quick slam shut of the wastegate under vacuum, but the spring should be more than enough to get things buttoned up, unless you need a new wastegate.

Don't think I'll be listening to SBR for any of my part installs. If you just think about it logically, it's pretty obvious that teeing into the BOV line is a crap way to do it. And if they're pushing this method for wastegates, who knows what'll come out on a more immediately vital part?

Thank you, exactly what i was trying to convey. And also nice to know that not "all dsm vendors" tell you to install in the bov too. I'm happy to see that changing.
 
With what I was asking before,
is there anything not right about tapping the boost gauge feed to the bov line? Theoretically of course since I realize this thread is 90% opinion based...
I normally tap to the fpr, but the awdlaser I have already had it tapped to the bov line and I never messed with it, and just left it how it was...
 
With what I was asking before,
is there anything not right about tapping the boost gauge feed to the bov line? Theoretically of course since I realize this thread is 90% opinion based...
I normally tap to the fpr, but the awdlaser I have already had it tapped to the bov line and I never messed with it, and just left it how it was...

I guess there isn't, but the fpr line seems much easier and closer to the firewall and cleaner. But still though, personally, i wouldn't mess with the bov line.
 
Logical deductions, teeing off the BOV line for wastegate actuation, pros and cons by part:
-BOV
Con:
Increased vacuum system volume leads to slower actuation, allowing more positive charge to backflow to the turbo. A boost leak only exacerbates the problem, as there is more overall charge in the intake tract to back-flow. Turbo lifespan will be shortened before rebuild/replacement becomes neccessary.
Pro:
Drilling/tapping a vacuum fitting into the compressor housing/outlet elbow is not neccessary, if one is not preexisting.

-Wastegate
Con:
Increased vacuum system volume slows wastegate response, increasing the likelihood of boost spike. BOV line is a manifold pressure source, ensuring that regardless of boost leaks your manifold will always receive the set pressure, even if the turbo must overspin its efficiency map to provide that pressure, resulting in hotter charge temperature (and over-rich running in the case of a boost leak). Operator will NOT be warned about the potential presence of the boost leak by a 'low boost' read on aftermarket boost gauge. Turbo lifespan will be lowered by consistent and continued overspin.
Pro:
Slightly faster wastegate closure on throttle-off due to effective 'vacuum-assist' of wastegate actuator spring, potentially providing minimal reduction to spool time on hard shifts or in a road racing environment.


If there's a flaw in my thinking, please feel free to point it out. Otherwise, there is very little gain (aside from the lazy factor) in the 'old' method, and a potential for markedly decreased overall turbo lifespan, especially in the case of a boost leak. Which also is less likely to be noticed by the driver, until the turbo craps itself.
 
Logical deductions, teeing off the BOV line for wastegate actuation, pros and cons by part:
-BOV
Con:
Increased vacuum system volume leads to slower actuation, allowing more positive charge to backflow to the turbo. A boost leak only exacerbates the problem, as there is more overall charge in the intake tract to back-flow. Turbo lifespan will be shortened before rebuild/replacement becomes neccessary.
Pro:
Drilling/tapping a vacuum fitting into the compressor housing/outlet elbow is not neccessary, if one is not preexisting.

-Wastegate
Con:
Increased vacuum system volume slows wastegate response, increasing the likelihood of boost spike. BOV line is a manifold pressure source, ensuring that regardless of boost leaks your manifold will always receive the set pressure, even if the turbo must overspin its efficiency map to provide that pressure, resulting in hotter charge temperature (and over-rich running in the case of a boost leak). Operator will NOT be warned about the potential presence of the boost leak by a 'low boost' read on aftermarket boost gauge. Turbo lifespan will be lowered by consistent and continued overspin.
Pro:
Slightly faster wastegate closure on throttle-off due to effective 'vacuum-assist' of wastegate actuator spring, potentially providing minimal reduction to spool time on hard shifts or in a road racing environment.


If there's a flaw in my thinking, please feel free to point it out. Otherwise, there is very little gain (aside from the lazy factor) in the 'old' method, and a potential for markedly decreased overall turbo lifespan, especially in the case of a boost leak. Which also is less likely to be noticed by the driver, until the turbo craps itself.


The flaw in your thinking is that your assuming that by teeing off the bov line that the bov isn't opening as fast as it would be if you weren't t-ing off the wastegate. 99% of the time the bov will still operate as designed. I have a tial style bov(50mm piston pretty much the biggest you can get for a dsm) I T off the bov line and my bov works flawlessly. The only time what your talking about is the case is when your line off the manifold is compramised. The distance between T off the BOV line and the mbc is about 6 inches I think my system is strong enough to accomidate the extra 6 inches.
 
Originally posted by oldman said:
Taking the pressure source from the j-pipe fitting has many benefits.

1. The main reason why alot of mbc instructions and some tech articles suggests to tap from the BOV line is because it's connected to the intake manifold, the argument is that this is more accurate because it's the same pressure the engine sees. In reality this is a non issue because the boost gauge is tap to the intake manifold no matter where you tap your mbc so there is no advantage in tapping the bov/manifold pressure as previously thought.

2. The proper functioning (opening and closing) of the bov depends greatly on the accuracy of the pressure in the vacuum hose you're thinking of tapping on or off boost so it's best to leave it connected directly to the manifold without any interference.

3. Tapping off the compressor/j-pipe offers the shortest vacuum hose route which greatly reduces the chance of boost spike.

4. In the case of boost leaks, tapping off the compressor/j-pipe will help prevent over boosting the turbo.

5. Hooking up a bleeder type mbc like the TurboXS standard mbc to the bov line will result in a vacuum leak as well as affect the working of the BOV.

Pay attention to #2 and #5, as they are directly related. I can think of more threads where moving the pressure source from the BOV line to the compressor/IC pipe fixed all the OP's problems than I can count.

Leave the BOV line alone. If Joe wants to run it that way, fine. Something tells me that nothing anyone says will change his mind about anything.
 
Pay attention to #2 and #5, as they are directly related. I can think of more threads where moving the pressure source from the BOV line to the compressor/IC pipe fixed all the OP's problems than I can count.

Leave the BOV line alone. If Joe wants to run it that way, fine. Something tells me that nothing anyone says will change his mind about anything.


Noone telling me to change my mind will do it, if it physically makes a positive difference then its enough for me, and going off the compressor hasnt so im still doing it the way that works for me. And i dont know why you singled me out, im not the only one that runs it that way and prefers it. But who am i to say.


Joe
SBR
 
Because you're a representative for a fairly major DSM shop, Joe. Instead of just another screwhead. You kinda should be expected to know your stuff better than the average newbie, if you want to portray the shop as experienced and knowledgeable.

Slippi, basic physics says it's not opening as fast. You sound like one of the 2Gers who insist that venting their BOV doesn't impact car performance, when they're only going on butt-dyno. It's simple physics that with a larger volume vacuum system, operation of the entire vacuum system will lag behind source conditions. This isn't hydraulics, it's just air. Air plays by certain rules. You may not be able to *notice* the problem as-is. That doesn't mean a problem doesn't exist. Try lengthening your vacuum lines by ten or twenty feet. Coil 'em up in the engine bay, and you'll see why having more volume than neccessary in a vacuum system, especially one with a single vacuum source is a bad thing. Just so you can notice/accept that there is a problem.
 
Pay attention to #2 and #5, as they are directly related. I can think of more threads where moving the pressure source from the BOV line to the compressor/IC pipe fixed all the OP's problems than I can count.

Leave the BOV line alone. QUOTE]

Hmm.. Makes sense, enough said for me.
I will move the boostgauge tap off the bov line to the fpr like how it is on my other dsm.
 
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