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BOV Vacuum Source

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SlickPyro

10+ Year Contributor
226
6
Jun 5, 2008
South Euclid, Ohio
Before I start, I have been searching and reading for an hour. I have seen alot of ms paint pictures of bov and mbc routings and I guess I just don't get it.

Here is my setup. Before I had a joeP mbc and it was run from the vacuum source on the left side of the intake which also went to my 1g bov. So it was T'd. I had no issues.

I installed a hallman pro mbc and just routed it the way I had it with the T and I noticed bov flutter. So I want to run a line from the intake right to the hallman pro. But that leaves me without a vacuum source for the bov. Can I use a nipple on the throttle body for the bov? And if so which one?

Also I have a punishment racing fmic and really do not want to drill a hole and tap a nipple into the j pipe for the mbc so i can use the intake source for the bov. So any help would be appreciated. Thanks!
 
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You want to run your wastegate directly to the MBC via the closest pipe/source to the compressor.
You want to run the BOV directly to the intake manifold, after the throttle plate.
 
Ok I drew a really crappy picture. I understand what you are saying as I read plenty of threads on this subject. I understand that the mbc should be run to a nipple on the j pipe but as I stated I have a punishment racing fmic and it has no nipple and I do not want to drill and tap one in. So it is running right to the manifold which as I read is just fine. But that leaves me with no vacuum source to the bov and I read that it is not supposed to be T'd.
 
I understand that the mbc should be run to a nipple on the j pipe but as I stated I have a punishment racing fmic and it has no nipple and I do not want to drill and tap one in.
If you don't want to do it right, don't ask how to do it right, just do it wrong.
 
I personally run the BOV as well as MBC off the intake manifold. Reason to NOT run it off the compressor/j-pipe is that the air is presumably changing temp/pressure after the intercooler, so the most consistent place to run your MBC from is the intake manifold.
 
I personally run the BOV as well as MBC off the intake manifold. Reason to NOT run it off the compressor/j-pipe is that the air is presumably changing temp/pressure after the intercooler, so the most consistent place to run your MBC from is the intake manifold.

That would be what I did whenever I installed my Joe P. Just get a small cap to put on the nipple on the J Pipe.
 
If you don't want to do it right, don't ask how to do it right, just do it wrong.

If it was meant to be done this way, your "right" way, I'm sure punishment racing would have put a nipple on the J pipe.

cjridert1 said:
I personally run the BOV as well as MBC off the intake manifold. Reason to NOT run it off the compressor/j-pipe is that the air is presumably changing temp/pressure after the intercooler, so the most consistent place to run your MBC from is the intake manifold.

This is helpful. Thank you. Do you have them T'd together on the same line? because this is the way I had it with the joeP and had no flutter but then switched to halman pro and noticed flutter. Just trying to make sure everything is runnin right.

DarkOne57 said:
That would be what I did whenever I installed my Joe P. Just get a small cap to put on the nipple on the J Pipe.

there is no nipple on the J pipe or I wouldnt have any issues. Thanks.
 
This is helpful. Thank you. Do you have them T'd together on the same line? because this is the way I had it with the joeP and had no flutter but then switched to halman pro and noticed flutter. Just trying to make sure everything is runnin right.

I have 4 vacuum fittings on the intake manifold. I have the more 'insignificant' things T'd (fpr, boost gauge, whatever) and the BOV and MBC each have their own vacuum port.
Shouldn't make a huge deal running a T in any of them, I assume those vacuum blocks distribute pressure reasonably. Try giving the BOV it's own line, can't hurt right?

Before I had a joeP mbc and it was run from the vacuum source on the left side of the intake

What does this mean? The 'P' port on the TB is a viable option or any port on the intake manifold is good news.
 
So u have an aftermarket intake. And Joe p is a type of mbc. Brass and looks like it was made at home depot. I had it run to the port on the intake that is on the front on the left like right behind injectors 3 & 4 and the had the bov t'd into the same line. I'm trying to figure out how people run it with a stock 1g intake. Thanks for the replies!

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If it was meant to be done this way, your "right" way, I'm sure punishment racing would have put a nipple on the J pipe..

Not at all! Most IC kits dont come with a nipple on them like that because most turbos have the pressure source coming off the compressor housing. So, IF you want to do this the correct way, you'll have to either take your compressor housing off and drill and tap a hole something like this guy did with his 16g > http://www.dsmtuners.com/forums/articles-turbo-system-intercooler/387331-adding-boost-source-16g-turbo-compressor-outlet.html . Or take your J pipe off and put a pressure source there.. If not, like Absit said if you dont want to follow the correct advise dont even ask.
 
I think ill email PR and see what they say. It's the 1g kit designed for 14b and 16gs. And those don't have pressure sources on the compressor housing. I read threads that said it was better to go to the intake because the mbc is using the actual pressure that the engine is seeing instead of before the intercooler and pressure drop. Id link to them but I'm on my Droid. That's a cool link, thanks for sharing that. I'd rather T it again and do some more driving before taking my J pipe off to tap it. I understand it might not be the right way but I'm sure many dsmers are running it with a T and no problems. I'm just trying to see how people are running there vacuum lines.

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My punishment kit had a nipple on the "L" pipe that connects after the J pipe...as with every other punishment kit I've seen...


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I personally run the BOV as well as MBC off the intake manifold. Reason to NOT run it off the compressor/j-pipe is that the air is presumably changing temp/pressure after the intercooler, so the most consistent place to run your MBC from is the intake manifold.
Except the consistency will be similar. The only way this would make a difference is if you were measuring your boost before the intercooler. A MBC is a dumb tool, it doesn't care what it gets, it's going to do what it does.

If it was meant to be done this way, your "right" way, I'm sure punishment racing would have put a nipple on the J pipe.
You don't seem to understand that Punishment sells that kit as one of the cheapest kits you can get, not one of the best.

The reason you don't want to T your MBC in to anything else is because an MBC is an intentional adjustable vacuum leak. Anything that's connected to it will be affected by it.
 
My punishment kit had a nipple on the "L" pipe that connects after the J pipe...as with every other punishment kit I've seen...


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Mine didn't and i never seen any kits from them that did, cause I have seen many threads like the op's.

I did something similar to what crash89 posted.
 
As mentioned, connect the MBC to the closest dedicated vacuum/boost source to the wastegate. If you have a nipple on the compressor cover, use it. If no nipple and you have a J-pipe, drill and tap a nipple onto the pipe. Same goes for a turbo without a j pip, just drill and tap onto the outlet pipe.

BOV needs a dedicated line and should be ran from the intake manifold just like how it came from the factory. Boost gauge generally gets teed into the FPR vacuum line unless you have enough free post TB ports to incorporate the factory PVC line and brake booster, as well as the aforementioned lines needed.
 
After reading through all of this I think you've titled your thread incorrectly, are you talking about the MBC here or the BOV? Assuming its your MBC read the below...

Remember, the closer the boost source is to the turbo the better so put it on the j-pipe or LICP just before the FMIC. Will "t"ing it into another vacuum/boost source off the IM work? Sure, but you'll experience boost spike and poor boost control. Do it the right way!

The tools you need to get the fitting into the IC pipe are a 1/8" to 1/2" step drill bit, drill, and a tap set. Any vacuum fitting will work and can be bought a Home Depot or any car parts store, I suggest getting a 1/8" NPT vacuum fitting similar to the one pictured below. Then just drill and tap a hole in your LICP and thread in the vacuum fitting (use RTV on the threads) and put the pipe back on and connect your vacuum line to the bov.

Heres what a step bit looks like...
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Heres what the 1/8" NPT fitting looks like...

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:dsm:
 
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^ good info. When I did he comp cover on my 16g, I found the source nipple and hen went to ace hardware and bout he tap and appropriate matching drill bit and did that way.
 
Thanks for all the replies I guess shoulda titled it bov and mbc vacuum source. I can probably squeek my 14b compressor housing out of there and put a nip on it. I'm assuming it has the same hole as the 16g pictured that can be used.

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I would agreee with Crash89. Follow the link he gave you to put a boost source on the compressor housing.

I did this to my old 16g and its worked great ever since. The OP of that tech write up actually came to me for advise on what else to incorporate in his write up. Id highly suggest doing it that way or tapping into the jpipe/LICP if you dont feel comfortable drilling into the compressor housing..
 
Doing it the way Tom (crash89) suggested is great! However, it requires you to remove the turbo and in most cases its already installed so doing it on the j-pipe or LICP is a lot easier.

:dsm:
 
If you put it on the J-Pipe, don't tap all the way down the tap or you can make the hole too big.
Test the fit a few times along the way.
Also, I always put some jb weld on the threads when screwing a fitting into thin-walled tubing for extra insurance.
 
I'm gonna go look at my turbo tonight. If the c clip is accessible ill do the compressor housing. If not ill pull the j pipe and tap it there. Thanks for all the help. Also I'm assuming I should get a new j pipe gasket too right? They aren't reuseable are they? I'll probably end up doing the j pipe regardless of the position of the c clip.

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The easiest is he jpipe if I is still on the car, other wise the turbo more then likely has to come out, mine did to find the clip ends and get a good position on it.
 
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