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  1. #1
    Senior Member Two Rings starfriend's Avatar
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    Replacing the N75 with a MBC? no?

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    Hi,

    Can i replace my N75 with a MBC by simply removing it, and clogging the hole in the TIP with a bolt or something? will the n75 need to remain connected in a loop system or what? How will this work with my Revo software? (default settings right now, and i dont have a sps).
    My guess is that i can just hook the MBC, and leave the n75 connected in the tip open as it is without limp or anything? but how will this affect my boost? if i set the MBC wide open so it charges to like 20psi?

    - star

  2. #2
    Veteran Member Four Rings old guy's Avatar
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    Re: Replacing the N75 with a MBC? no?

    Run it in parallel. See post #9: Clicky click

  3. #3
    Senior Member Two Rings starfriend's Avatar
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    Re: Replacing the N75 with a MBC? no?

    Well, yeah, but still using the N75, wont that kind of kill some of the point with MBC? to have it spool and respond a bit faster? thanks for the link btw!

  4. #4
    Veteran Member Four Rings old guy's Avatar
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    Re: Replacing the N75 with a MBC? no?

    give it a try and see if you like it. I think you will find that it becomes "all or none" with the boost and the car will be harder to modulate. It may also throw it into limp mode quicker.

    Edit: to answer your original question: Leave the N75 hooked up electrically. Leave the line from the N75 to the TIP intact. Remove the other two lines in and out of the N75 and insert the MBC there. Run a loop to connect the in/out ports on the N75 (keeps dirt out for when you hook it back up after you decide the MBC sucks!)

    Have fun!
    Last edited by old guy; 08-29-2008 at 05:32 AM.

  5. #5
    Veteran Member Four Rings dougyfresh's Avatar
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    Re: Replacing the N75 with a MBC? no?

    Quote Originally Posted by old guy View Post
    Edit: to answer your original question: Leave the N75 hooked up electrically. Leave the line from the N75 to the TIP intact. Remove the other two lines in and out of the N75 and insert the MBC there. Run a loop to connect the in/out ports on the N75 (keeps dirt out for when you hook it back up after you decide the MBC sucks!)

    Have fun!
    Correct. I have my N75 plugged in but no lines running to it. This avoids a CEL and allows me to run my EBC.
    -Doug



    2001 A4 Avant [silver on black]
    2002 A4 Avant [denim blue on platinum/black]

  6. #6
    Senior Member Two Rings starfriend's Avatar
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    Re: Replacing the N75 with a MBC? no?

    thank you for your reply old guy, one more thing, what happens if the MBC is wide open and the boost is at full? will the fuel adjust somehow or will my car be runnig lean as hell? if so, im not even gonna try.. fine adjusting it will probably be a PITA

  7. #7
    Veteran Member Four Rings old guy's Avatar
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    Re: Replacing the N75 with a MBC? no?

    Quote Originally Posted by starfriend View Post
    thank you for your reply old guy, one more thing, what happens if the MBC is wide open and the boost is at full? will the fuel adjust somehow or will my car be runnig lean as hell? if so, im not even gonna try.. fine adjusting it will probably be a PITA
    Your fueling should be OK.

  8. #8
    Senior Member Two Rings starfriend's Avatar
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    Re: Replacing the N75 with a MBC? no?

    what? really? like, i can use this to run high boost (like 20psi) till i get my SPS? (loading about 12now from factory, REVO tune GTRS) if so, this could not have been cooler. I thought that stuff was "fixed" tho. (preset)

  9. #9
    Veteran Member Four Rings A4Dit's Avatar
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    Re: Replacing the N75 with a MBC? no?

    Be advised, the N75 regulates boost more conservatively and gives it to you more linear; smoother I should say. The MBC is does away with this, the way boost comes will come on is very sudden and strong. I prefer the N75 but everybody is different.
    BetaAlphaTauMember #39 GTRS Powered/Revo Tuned

  10. #10
    Veteran Member Four Rings A4Dit's Avatar
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    Re: Replacing the N75 with a MBC? no?

    Quote Originally Posted by starfriend View Post
    what? really? like, i can use this to run high boost (like 20psi) till i get my SPS? (loading about 12now from factory, REVO tune GTRS) if so, this could not have been cooler. I thought that stuff was "fixed" tho. (preset)
    The Revo tuner preset your car to run 12psi when he tuned it? You can run 20psi w/o any problems.
    BetaAlphaTauMember #39 GTRS Powered/Revo Tuned

  11. #11
    Senior Member Two Rings starfriend's Avatar
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    Re: Replacing the N75 with a MBC? no?

    Quote Originally Posted by A4Dit View Post
    The Revo tuner preset your car to run 12psi when he tuned it? You can run 20psi w/o any problems.
    yeah, thats default from tuner afaik (12psi var roughly calculated from 0.7BAR), isnt it T3 and B5 when i get it? i have been waiting so long for the SPS to get the boost going and i can just use the MBC.. god damnit;) 1hour til im off work, guess what im gonna do today? :D

  12. #12
    Veteran Member Four Rings texasboy21's Avatar
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    Re: Replacing the N75 with a MBC? no?

    just leave it plugged in the hole in the tip and place the lines onto the mbc, thatll work great

    barrett
    2003 A4 1.8TQ
    APR stg2+, 240mm clutch, 12lbs flywheel, MTM 420cc injectors, EuroCode FMIC, PSi testpipe, Techtonics Tuning downpipe, Forge TIP, Hyperboost DV, B5S4 calipers, Goodridge SS lines, Stern snub, motor and transmission mounts, JHM SS shifter, solid linkage, stabilizer bushing and weighted knob, Vogtland Jr. Cup Kit, RS4 Rear sway bar, Team Dynamics Motorsports lightweight wheels

  13. #13
    Veteran Member Four Rings 500HPS5's Avatar
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    Re: Replacing the N75 with a MBC? no?

    leave the N75 in the TIP and just remove the boost signal lines, loop the input and output with a 6mm vacuum line.

    If you run a MBC without being on boost 9 with the SPS your requested boost will be lower than your actaul boost, the car will not run on the sweet spot of the MAP but it will run fine. You will not see maximum power potential.

    On boost 9 with the SPS the requested will be 2540 at all times, this is the maximum the software allows (constraints of ME7)

    I run a EBC set at 20psi for pump gas and 22 or 25 for race gas, it took a bit to tune the duty cycle but my boost is very smooth and linear.

  14. #14
    Senior Member Two Rings starfriend's Avatar
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    Re: Replacing the N75 with a MBC? no?

    im not after full potential ofc, i just want more juice till i get the SPS.. but i dont quite ge ti,

    you want me to leave the outlet on the turbo, and the wastegate niple left wide open? and most of all, is the thing i was planning to in the last post dangerous to my car?

  15. #15
    Senior Member Two Rings starfriend's Avatar
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    Re: Replacing the N75 with a MBC? no?

    Quote Originally Posted by starfriend View Post
    im not after full potential ofc, i just want more juice till i get the SPS.. but i dont quite ge ti,

    you want me to leave the outlet on the turbo, and the wastegate niple left wide open? and most of all, is the thing i was planning to in the last post dangerous to my car?
    and how does it NOT matter if i boost 2psi or 20psi, when it comes to the fueling? what measures that?

  16. #16
    Veteran Member Four Rings 500HPS5's Avatar
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    Re: Replacing the N75 with a MBC? no?

    No, you need to have an actual boost controller or you will peg boost and cause issues

  17. #17
    Senior Member Two Rings starfriend's Avatar
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    Re: Replacing the N75 with a MBC? no?

    What i've figured, but is the fueling only depending on the MAF? hmm.. always thought there where more balls in the air ;-)

    Oh well, ill try looping the N75 tomorrow, and using a MBC for the rest, to try it out:)

    Thanks for your help and replies.

  18. #18
    Senior Member Two Rings starfriend's Avatar
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    Re: Replacing the N75 with a MBC? no?

    tried to install the MBC today, by leaving the N75 plugged in the tip, and running a hose in loop "inlets\outlets" on the n75.

    The mbc seemed to not have any effect (i take it turn it against "-" is less boost? a forge unos).. first i thought it was because i plugged the wg\pressure wrong, so i swapped pos, but that didnt change anything.. unless i actually plugged them back where them was.. which would be embarrasing... ideas? is "+" less boost? what am i missing?

    btw, is this mbc reliable? and what will happen if it "breaks" and i overboost without noticing it? (i have a gauge tho:p)
    A4/B6-2001 [Eurospec]
    430cc Genesis //GTRS// REVO //ATP// CUSTOM 3" EXHAUST w/ Magnaflow Mufflers //BSR OPTIFLOW INTAKE// FORGE SPLIT-R //Neuspeed Xtreme TIP// Racetec FMIC //Hitachi E//

  19. #19
    Veteran Member Four Rings Molotov's Avatar
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    Re: Replacing the N75 with a MBC? no?

    + is more boost. not certain and probably way off, but i think 4 clicks is 1 psi...again i'm probably wrong
    - Scott

    Das Build Thread

    Performance parts for sale:
    PTE 6262 V-Band - 42DD Stealth Catch Can - MagnaFlow Race Muffler - Vibrant 4" Filter - MAF 4" Housing

  20. #20
    Senior Member Two Rings starfriend's Avatar
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    Re: Replacing the N75 with a MBC? no?

    that sounds just about right, cause there is a million clicks;) well, then i dont know what the hell i did wrong.. it boosts +1bar ( i lay off there ) and its turned all the way on "-"...
    A4/B6-2001 [Eurospec]
    430cc Genesis //GTRS// REVO //ATP// CUSTOM 3" EXHAUST w/ Magnaflow Mufflers //BSR OPTIFLOW INTAKE// FORGE SPLIT-R //Neuspeed Xtreme TIP// Racetec FMIC //Hitachi E//

  21. #21
    Senior Member Two Rings starfriend's Avatar
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    Re: Replacing the N75 with a MBC? no?

    Quote Originally Posted by starfriend View Post
    that sounds just about right, cause there is a million clicks;) well, then i dont know what the hell i did wrong.. it boosts +1bar ( i lay off there ) and its turned all the way on "-"...
    tried swapping the hoses, and having it to "-" all the way, nothing works, so it must be broken.. damnit the f...
    A4/B6-2001 [Eurospec]
    430cc Genesis //GTRS// REVO //ATP// CUSTOM 3" EXHAUST w/ Magnaflow Mufflers //BSR OPTIFLOW INTAKE// FORGE SPLIT-R //Neuspeed Xtreme TIP// Racetec FMIC //Hitachi E//

  22. #22
    Veteran Member Four Rings Molotov's Avatar
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    Re: Replacing the N75 with a MBC? no?

    what psi are you trying to obtain? youre talking about setting it all the way to "-" but why? Didn't it come with a print out for the orientation on install? I have the same mbc, no problems with it.
    - Scott

    Das Build Thread

    Performance parts for sale:
    PTE 6262 V-Band - 42DD Stealth Catch Can - MagnaFlow Race Muffler - Vibrant 4" Filter - MAF 4" Housing

  23. #23
    Senior Member Two Rings starfriend's Avatar
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    Re: Replacing the N75 with a MBC? no?

    im trying it all the way "-" to insure that it works before i start tuning, i cant just put it in the middle and floor it, that would blow the shit off the turbo. And all the way turned on "-" should not surpass 1.2bar (like 15ish psi). So thats why. I want to use it so i can run 20psi (n75 only does 10psi now, due to the chip, waiting for my SPS).

    Print out or not, i have tried it both ways, so it shouldnt matter.
    A4/B6-2001 [Eurospec]
    430cc Genesis //GTRS// REVO //ATP// CUSTOM 3" EXHAUST w/ Magnaflow Mufflers //BSR OPTIFLOW INTAKE// FORGE SPLIT-R //Neuspeed Xtreme TIP// Racetec FMIC //Hitachi E//

  24. #24
    Registered Member One Ring
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    So wait does your chip not let you go over 10psi or is your N75 bad or possibly are you running stock software? I realize me asking the stock software part maybe a little foolish but that is about what a stock setup does also IF you are chipped to only run x amount of boost and you decide to go to +x with a MBC then how does fuel keep up?

  25. #25
    Veteran Member Four Rings MikTip's Avatar
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    I get 21 psi all the time with an N75 "J" and APR K04 tune

    034906283J.

  26. #26
    Veteran Member Four Rings texasboy21's Avatar
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    You need a better boost controller of you want to run it independent of the N75. Our cars need a ball and spring/bleed valve combo style mbc, like the TurboXS HPBC.

    http://turboxs.com/shop/boost-contro...ontroller.html

    You will also need to log your car in all sorts of boost situations (low speed/RPM cruising, WOT through various gears, etc.) to have a solid understand of your current boost onset. Your MBC will have to mimic those boost threasholds by + or - 300mbar, because if there is any more variance than that you will hit limp mod, your fueling will go to shit, and you will run lean as hell until your engine blows.

    Now, all that said, your REVO tune should most definitely boost more than 10PSI. You either 1. have something wrong with your car that needs to be address; slapping on a MBC is literally the worst thing you can do or 2. need to go back to your REVO tuner and have they adjust your tune's setting bc they did not set it correctly.

    Get our car all buttoned up, and/or your revo tune issue addressed, then think about the MBC.
    2003 A4 1.8TQ
    APR stg2+, 240mm clutch, 12lbs flywheel, MTM 420cc injectors, EuroCode FMIC, PSi testpipe, Techtonics Tuning downpipe, Forge TIP, Hyperboost DV, B5S4 calipers, Goodridge SS lines, Stern snub, motor and transmission mounts, JHM SS shifter, solid linkage, stabilizer bushing and weighted knob, Vogtland Jr. Cup Kit, RS4 Rear sway bar, Team Dynamics Motorsports lightweight wheels



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