Boost Questions (MBC, BOV dump tube)

[Araesk]

I've been looking into how to upgrade my 95 GST, and I went to detach the Boost Control Solenoid restrictor from my car and when I got to it I realized there are no hoses attached to it. After reading around I learned that people disconnect it when they add a MBC. Anyway I continued on and removed the restrictor from the solenoid anyway and reconnected it and plugged it back in again (it was plugged in before i touched it.) So I decided to look if there was a MBC on my turbo, and followed the line and found this before the Y splitter.

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I'm not sure if this is a MBC or not.

Then after that, i find the Y splitter, one going to the BOV, and the other to the top of the intake manifold. I just am not sure if I need to go pick up a MBC if I want to try to push more boost.

Also I heard that detaching the dump tube from the BOV would increase the pressure build up by the turbo resulting in more boost, and I am not 100% certain if this is it; and if it is, how I would go about plugging it when detached.

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(sorry for the low quality picture on this one)

Thanks for taking the time to read this fairly lengthy post and giving me some input!

 

[iBoostDSM]

That looks like a mbc, not a nice one, but looks like one.

And that "dump tube" is to recirculate the bov back to the intake. DON'T TOUCH IT! Taking it off will give you nothing but problems and in no way any performance increase. Before turning up the boost I would get a boost gauge (if you don't have one), a wideband and a fuel pump.

To help us give you better advice on your car, update your mods list in your profile.

 

[Kyle's_91TsiAWD]

The first picture is probably an old mbc or a homemade one. Your mbc should not be tapped into your bov line. the line from the the top of your bov should go to the intake manifold. Your mbc should have one hose going to your wastegate and the other going to a boost source either j-pipe or intake manifold. As for the vent for your bov you should leave it how it is.

 

[Lofty]

Get a new MBC. That one looks like garbage. Get a nice one. Do not turn your boost up with atleast a good boost gauge, and a Wideband. Dumping your BOV to the atmosphere is never a good idea, your car will stall between shifts and in general not run right. If you want to vent, get DSMlink. I know it sounds cool but the performance losses are not worth it. If you want to turn the boost past 20 you will more than likely need an MLS headgasket, ARP headgasket. A fuel pump that is worth a damn, like atleast a walbro 255lph. Turn it up to 15 max and go have fun. Make sure you check for boost leaks and make sure everything in your car is up to service. Uhhhh I am not sure what else Im missing.

So yeah.

Judging by the oil everywhere in the bay, Id suggest you take care of whatever is leaking and then play with boost levels.

 

[Araesk]

Alright I was just reading up on the "Turbo: The Basics" post and saw that there should be a direct line from the turbo to the BOV. So I will get around to doing that sometime tomorrow when I have the opening. Should I bother to go on ebay and pick up a different $15 MBC?

As for the the setup for my pressure lines it should go like this:

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As for why I don't update my mods, umm, I bought the car about 2 months ago and am still figuring out what has all been done to it seeing as this is the first time I've ever decided to start working on cars. (I was big on PC's prior.)

To Lofty: I'm going to be picking up hopefully new valve cover gaskets soon and a new PCV valve. Then grab a walbro 255 and some 750cc injectors. I'd make the most out of that, and then probably from there grab a intercooler setup to replace the factory one. Maybe grab new exhaust headers. Besides that I don't know what else I would do to it, don't want to get too crazy.

 

[Kyle's_91TsiAWD]

i wouldnt hook your bov up to your turbo you should switch the bov line to the intake manifold and the line from the mbc to the turbo.

 

[iBoostDSM]

Most people run the line from the bov to the intake mani. Then the bottom end of the mbc to the turbo and the side to wastegate.

An ebay mbc is probably just as good as your current one or worse. Buy one and be done. Look into getting a Hallman Pro mbc. You'll probably be able to find one around $70 or less in the classifieds.

If you're planning on getting larger injectors you'll need something to tune with. Almost everyone will tell you to get dsmlink. Checkout the tech guide if you haven't yet.

http://www.dsmtuners.com/2g-dsm-turbo-upgrade-path

Make sure all maintenance is done first!

 

[Araesk]

So BOV-Intake Manifold| MBC linked to turbo and wastegate?

 

[iBoostDSM]

Correct

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[Araesk]

Alright I'll go ahead and take care of the lines tomorrow after school in the lot. Threw a 10mm socket wrench and a flathead in my backseat to help should i need it.
Quick side question, what is the idler pulley really do on the timing belt?

 

[Marchev]

Alright I'll go ahead and take care of the lines tomorrow after school in the lot. Threw a 10mm socket wrench and a flathead in my backseat to help should i need it.
Quick side question, what is the idler pulley really do on the timing belt?

Nothing much, its there to reroute the timing belt, take up slack etc. Its just a normal pulley