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Thread: MBC install

  1. #1
    crazydriver81's Avatar

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    MBC install

    Hi VR-4 pros!

    I need an advice, where to fit my MBC. Does it matter, how lond the vacuum lines become?

    I have got myself a Forge Unos manual boost controller (ball&spring type). The plan is to fit it on the engine bay wall, next to the resistor pack for the injectors. I need to put it between the intake ellbow and OEM boost solenoid. When installing the MBC on the fire wall behind the engine, I need to use longer vacuum pipes (from intake ellbow to MBC and from MBC to OEM boost solenoid).

    Will there be any effect on boost build up or boost response of the solenoid?
    Would it be better to keep vacuum lines short or doesn't it matter at all how long they are?

    Any info is highly appreciated. I'd rather look for another place to put the MBC, as having troubles after intsallation.
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  2. #2
    Chris.W's Avatar

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    Is it not supposed to be fitted before the boost solenoid?

    Between the waste gate actuators and the solenoid? Thus bleeding off the pressure before the solenoid see's it allowing you to produce a higher boost.


    Don't think it maters how long the vac lines are aslong as they are secure and not leaking.
    Not sure, I have completely bypassed my original boost solenoid in favour of an electronic boost controler which has a replacement solenoid anyway.

    I'm sure someone who knows more about this stuff will be along shortly.
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  3. #3
    adaxo's Avatar

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    I don't think that length of pipe will make much difference, look how long is dv pipe, as long as pipe is firm you should be ok to go on to bulk head with your MBC
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  4. #4
    crazydriver81's Avatar

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    Quote Originally Posted by Chris.W View Post
    Is it not supposed to be fitted before the boost solenoid?

    Between the waste gate actuators and the solenoid? Thus bleeding off the pressure before the solenoid see's it allowing you to produce a higher boost.
    Interesting. According to what I have found, the red tipped pipe at the inlet ellbow is the one to Play with. The solenoid will get the pressure from there to recognize, when to move the actuators. Changing the pressure there will lead to a later detection of boost and later reaction of the actuators - leading to higher boost. Or am I completely wrong now?

  5. #5
    Nick Mann's Avatar

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    No, that's right Stefan.

    Most MBCs are plumbed in there. Remove the red tipped pipe from the inlet elbow, put a new pipe on the inlet elbow and stick your MBC in between.

  6. #6
    Chris.W's Avatar

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    Was me that was confused not you. Was thinking of the instalation of my EBC, but then that completely removes the factory solenoid.

    Anyway, told you someone smarter and more awake would be there to answer.

  7. #7
    crazydriver81's Avatar

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    Thanks a lot! I am out into the garage now

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    Quote Originally Posted by Nick Mann View Post
    Remove the red tipped pipe from the inlet elbow, put a new pipe on the inlet elbow and stick your MBC in between.
    Is plumbing in an MBC as easy as that then?

    My mate has a TurboSmart boost 'T' but has no confidence to fit it. Can it just then be adjusted by turning it down from fuel-cut?

  9. #9
    Nick Mann's Avatar

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    Fundamentally, yes.

    All you are doing is bleeding off some pressure before it gets to the boost solenoid, so the control is done the same but the actual pressure is higher, offset by the MBC.
    Increasing boost always has a potential risk, you can minimise that risk by doing it on a rolling road so that AFR and knock is being monitored. However there are MANY cars on here that have had the boost increased with an MBC and just turning it up until fuel cut is hit then backing it off again.

  10. #10

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    Excellent.

    Next time I see him, we'll give it a go.

  11. #11

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    Quote Originally Posted by Nick Mann View Post
    Fundamentally, yes.
    On the front of the MBC it says "Wastegate -->"

    Does the arrow point at the intake elbow or away from it?

    I know it sounds dumb, but I'd rather check than do a massive wrong'n on my mates car!

  12. #12
    crazydriver81's Avatar

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    Away from the ellbow, towards stock solenoid

  13. #13

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    Quote Originally Posted by crazydriver81 View Post
    Away from the ellbow, towards stock solenoid

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    Cant belive it is that easy installing a MBC

  15. #15
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    yes very simple, it is the setup that has to be done correctly start low and build the pressure up slowly until you hit fuel cut then back it off a bit.

    unless you have capability of flashing the ecu then you can raise the fuel cut level and set the boost to whatever level you want. but if you can do that why would you not use the factory boost solenoid and set the required boost level via the ecu.

    Bye for Now!

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