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Help with MBC, cant add more boost

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Old 06-27-2007, 11:25 AM
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Default Help with MBC, cant add more boost

So last night I tried to turn the boost up, here is the boost controller I have

http://www.jegs.com/webapp/wcs/store...0002_315228_-1

Also there are 9psi springs in the gates

First we turned it up 6 clicks, and the boost went up a little, next 6 more clicks, nothing, then 10 more clicks, nothing.

Here is how we have it setup

Manifold Pressure ---> Boost T ---> T --( two lines )--> Waste Gates Low Side

AFRs were in the 11.4 area timing 20deg
Old 06-27-2007, 11:45 AM
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Which gates are you running? If it's Tial it needs to go to the side port not the bottom port.
Old 06-27-2007, 12:00 PM
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There is one port on the top and one on the lower side - i call that the bottom.

They are tial 44 vband
Old 06-27-2007, 12:31 PM
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Depends how the gates are mounted as to top/bottom...lol...

The port in the center of the removeable cover should be vented to air.

The other port takes the pressure reference.
Old 06-27-2007, 12:53 PM
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Here is how its hooked up
Attached Thumbnails Help with MBC, cant add more boost-tial_44mm_cross.jpg  
Old 06-27-2007, 03:09 PM
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Originally Posted by Boostaholic
Here is how its hooked up
Thats the problem it seems like.

Tial's website shows the line coming off the top of the gate goes into the MBC, then the outlet of the controller goes into a T where it joins up with the line for he side of the gate. The T also has a reference line to anywhere on the pressure side. Check this out and click on wastegate install diagram:

http://www.tialsport.com/techincal.htm
Old 06-27-2007, 04:53 PM
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I was under the impression that a boost controller bleeded off pressure from the bottom, I'll try it the other way tonight and post up the results.
Old 06-27-2007, 05:23 PM
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You may be overcoming the 9lb spring if you have a lot of exhaust pressure. Meaning that the wastegate may be opening solely because of that. What you CAN do, and I stress that this would have to be done EXTREMELY carefully, is just to test, pull the boost reference off the wastegate. Then slowly get into boost... if you see the boost going higher than you want, let off right away. If the boost goes higher than it would with the MBC attached, then the spring is not your problem. HOWEVER if boost will not go any higher that what it was with the MBC connected, the you are pushing open the wastegate with the exhaust and need stronger springs.

Once again be EXTREMELY careful if you decide to test it in this manner, and I take no responsibility if you overboost and blow stuff up
Old 06-27-2007, 05:43 PM
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I know the dangers of running with a unreferenced waste gate, and we might try that if hooking up the mbc different does not work.
Old 06-27-2007, 05:48 PM
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Run a bleeder type regulator to the top of the gate. We ran references from the turbo outlets (or in your case the manifold) directly to the side (which is what is normally reffered to as the 'bottom' of the gate). Then we ran a simple Turbonetics manual boost controller off of manifold pressure to the top of the gate (the one you currently have open to atmosphere). All it does is bleed off some of the pressure and put the rest on the top of the gate which makes it harder for your bottom/side port pressure source to lift up the valve (ie more boost). My pressure never varied more than a half psi once we got to the regulating point.

Hydrostream is on the money with the exhaust back-pressure unseating the valve.

The one you have now acts a lot differently because it doesn't allow any pressure to pass until you get to the threshhold you have it set to. This means if you have enough exhaust back-pressure, you will unseat your wastegate valve and be unable to make any more boost.
Old 06-27-2007, 06:43 PM
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ok ltl im going to go give it a shot in a bit here, just leaving the office in a few minutes.

thanks for the tips
Old 06-27-2007, 07:17 PM
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Originally Posted by Boostaholic
ok ltl im going to go give it a shot in a bit here, just leaving the office in a few minutes.

thanks for the tips
Do you have the other style of boost controller? The one you have won't work exactly the way I described.
Old 06-28-2007, 01:54 AM
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It did not work, so I unhooked the bottom ports on wastegates and it still only just came up to 10.

I'm pretty sure at this point I have a big exhaust leak in one of my gaskets some of the bolts are loose on the driver side manifold I noticed after I thought about exhaust leaks.
Old 06-28-2007, 02:46 PM
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I'd be willing to bet you're pushing the WG open... how much boost do you want to run? A 9psi spring vs a 1 bar spring is a HUGE difference in resistance, and will probably solve your problem as long as you can run ~1 bar or more all the time.
Old 06-28-2007, 05:27 PM
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Originally Posted by HydroStream6
I'd be willing to bet you're pushing the WG open... how much boost do you want to run? A 9psi spring vs a 1 bar spring is a HUGE difference in resistance, and will probably solve your problem as long as you can run ~1 bar or more all the time.
I'm still going with hydrostream's line of thinking even knowing you had a small leak.
Old 06-28-2007, 09:40 PM
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Ok I ordered 1 bar springs
Old 06-28-2007, 09:50 PM
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Originally Posted by Boostaholic
Ok I ordered 1 bar springs
Let us know. It's Chris right?
Old 06-28-2007, 11:38 PM
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Yep, Chris.

Also got the new exhaust gaskets so I think I'll put them on too and see what it does.

It also seems like its spooling a lot slower than it did last year, but I could just be getting used to things too. Kind of like how my R1 felt insanely fast when I first got it but now its just normal.
Old 06-29-2007, 07:25 AM
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Originally Posted by Boostaholic
Here is how its hooked up

That's the correct routing.
Old 06-29-2007, 07:40 AM
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If you're thinking a R1 is just normal then you are a speed junkie. They are nothing but normal!


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