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dumb MBC question

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Old Apr 15, 2012 | 08:09 PM
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Default dumb MBC question

Alright I know this sounds like a dumb question I just wanna be sure so I don't over boost my motor and blow it up. OK I'm wondering if my MBC should be closed off for no boost gain, i would be teeing off my current WG signal line and running it to my MBC then to the top port of my WG. I am assuming I want the MBC in the closed position so it does not put pressure on the back side of the diaphragm,then you start opening it to increase boost
pressure. Is this correct?
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Old Apr 16, 2012 | 12:12 PM
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Anyone?
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Old Apr 16, 2012 | 12:32 PM
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depends on the boost controller you are using... most manual boost controllers interrupt the reference line to the bottom of the wastegate, by utilizing a ball and spring to increase resistance and offering up more boost.

or they Bleed the reference so the wastegate sees less...

what boost controller are you using...
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Old Apr 16, 2012 | 12:33 PM
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mine is closed...then to open

you need boost pressure from the turbo to put pressure on the waste gate in order to keep it closed...mbc closed = no extra pressure
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Old Apr 16, 2012 | 12:37 PM
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Normally you would reference the intake manifold to the bottom port of wastegate. When intake pressure = spring pressure you stop making more boost. The manual boost controller goes in that line. It normally passes all signal through. To increase boost you increase pressure on the check valve. This limits the amount of pressure getting sent to the WG and raises boost accordingly.

This only applies to a simple ball check valve type controller.
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Old Apr 16, 2012 | 01:04 PM
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Originally Posted by 01Z28Camaro
Mine makes 10 psi with MBC turned all the way out, then 17 with it all the way in. That's at the bottom port. Now to go higher then 17, do I change it from bottom port to top and start with MBC turned all the way in? Would it start at 17 psi and go up as I turn it out?
correct, T off your intake or compressor reference, and then goto both ports, should be 17lbs just like when your MBC is topped out...

then you can reconnect it to the bottom line from the T to the bottom of the WG and you should be able to get another 7psi most likely
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Old Apr 16, 2012 | 01:41 PM
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Or run a stiffer spring.
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Old Apr 17, 2012 | 12:13 AM
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Already got 2 springs in my gate. But I want to turn it up more for tuning purposes so I can put a eboost in later. I honestly don't remember the brand its basically a old school air pressure regulator mbc.I was thinking the best way is to
put resistance on the the top of
the diaphragm hence the
question. Inline on my
reference line is obvious. I'm
gonna try the way denmah was mentioning. Right now I'm at #10 but wanna work my tune up to around #18ish.
Thanks
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