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Manual Boost Controllers

Discussion in 'A3/S3 Forum (8L Chassis)' started by Welly, May 18, 2010.

  1. Welly
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    Welly VX220 SC Driver :)

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  2. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Fitted an Apexi to the Polo... using a Forge UNOS on my car atm... works well...

    Might look into an electronic controller at some point but would only need to be a simple one as I don't have much issue putting the power down :)

    <tuffty
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  3. Mr.G
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    Mr.G Active Member

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    Question....why do you need to run a manual boost controller? Does the ECU not set this?

    Pardon my ignorance, I'm learning :)

    G
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  4. badger5
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    badger5 RIP S3dave Site Sponsor

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    MBC is a simple device.. ball and spring..

    ecu is trying to control a frequency valve by reading map sensor input of actual boost and in turn reacting to this to control the n75's duty cycle to achieve the boost the map is asking for.

    ecu can struggle to maintain this PID control of this loop, which is why on modded cars, which no longer confirm to "factory" components, its not surprising it sometimes does'nt behave as consistently as you would like, and diving into the PIS control within the me7 ecu, is something people just dont or cant do. MBC is a very cheap yet effective mod, and is often "spike" free, which is a common issue on k0x type units which are being worked hard
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  5. Welly
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    Welly VX220 SC Driver :)

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    As Bill said above.

    As I now have a reasonably well modified engine, the N75 is no longer controlling the boost delivery the way that I want it to. With an MBC I can set the boost config to how I want it to be delivered, I am also intending on pushing the turbo harder for a furhtur 1 - 2 PSI.

    To be honest, my engine config now allows me to fiddle. I have a large port head, and forged rods meaning that larger boost pressures are less of an issue when correctly monitored. I feel that there is more to come from my standard K04 turbo on my setup, as monitoring the N75 Duty Cycle on a regular basis shows that the valve is not being 'fully' opened. This suggests that there is more boost to be delivered.

    Even if that is not the case, MBCs generally allow quicker spool up (the reason being that they simply do not open AT ALL until set pressure, unlike the N75), and they also tend to hold the boost better throughout the rev range.

    MBC on a standard engine - not really a good idea. You will get limp mode, and potential mechanical problems, such as bent rods. And thats bad. Very bad.
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  6. Welly
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    Welly VX220 SC Driver :)

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    The main reason I woul like one is that it could function as a digital boost gauge for me at the same time - which would be nice.
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  7. Mr.G
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    Mr.G Active Member

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    Thanks Badger/Welly. Useful laymans terms information. :icon_thumright:

    So on my car which has an APR remap the ECU/N75 valve are what control the boost into the engine?

    G
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  8. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Fitting an MBC to my engine has given me the boost control the ECU was struggling to cope with.... Not a fault of the N75 it should be pointed out as Bill still runs one on his race Ibiza albeit with a standalone ECU... he gives it a duty cyle and it just does it... ME7 (as Bill has already mentioned) just doesn't appear as capable once you get into the realms of fairly seriously modded engines...

    Before fitting the MBC my boost would hit and initially hold 1.7bar then as the revs increased would waver between 1.4bar and 1.6bar or occasionally hold at 1.6bar and slowly drop off higher up the rev range... now it just holds the 1.8bar I set it too all the way to the redline and the car feels much much smoother and more powerful than before...

    <tuffty/>
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  9. Welly
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    Welly VX220 SC Driver :)

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    Yarp. ECU has a MAP Sensor to tell it what pressure is in the charge system.

    ECU requests X boost from the turbo.

    MAP Sensor reads Y from the charge system.

    ECU compares X and Y (VAG COM block 115, requested vs actual).

    ECU opens N75 valve more or less, depending on what the comparison of X and Y is (i.e. more than requested, or less than requested).

    And there you have it.

    Problem with the N75 valve, is that - to a degree - it is always slightly open. The way it works is a flap inside if you like, which opens and closes. The ECU provides it with an On/Off feed, which opens and closes the flap.

    More can be read here: http://www.seatcupra.net/forums/showthread.php?t=10170 as I'm just retyping what has already been written, and I am too hung over for that.... LOL.
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  10. jim s3
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    jim s3 Member

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    I have the aem boost controller gauge and it easy to wire in works a treat as well
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  11. Welly
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    Welly VX220 SC Driver :)

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    Link me..... :)
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  12. jim s3
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    jim s3 Member

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    Can't on my phone search it on google
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  13. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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  14. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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  15. Welly
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    Welly VX220 SC Driver :)

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    Yeah, I saw that one as well to be fair. Although I must admit, it does look a bit 'Casio'.

    I like the 4 boosst presets though - that would be useful for motorway journeys and the like.

    I'll prob get a Ball and spring one to begin with, then move up to a digital one.

    Fitting an MBC closes what I consider to be a boost leak in the first place - the N75 to TIP. I'm expecting to see 1 PSI from that to be fair.
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  16. Welly
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    Welly VX220 SC Driver :)

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  17. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    He will have to be good then, I got game...

    [​IMG]

    <tuffty/>
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  18. Welly
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    Welly VX220 SC Driver :)

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    LOL I have used most of the above on Call Of Duty....
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  19. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    I have used all of the above on consenting adults ;P

    <tuffty/>
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  20. JD09
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    JD09 I'm not modding, I'm improving

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    Getting the big guns out, eh Paul.

    Sorry.

    Thanks for the info in the thread, started on this site with no idea what MBC actually stood for! Now I know what it actually does!
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  21. Welly
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    Welly VX220 SC Driver :)

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    LOL, every day a learning experience on ASN.... :thumbsup:
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  22. Plunky
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    Plunky Member

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    so do you guys use the MBC on its own? or in series with the N75?
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  23. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    On its own at the moment... an MBC can be used alongside an N75 to prevent boost spikes and smooth out the boost curve..

    I may try it with the N75 at some point but the main reason I am using one is because the ECU does not appear to be able to control boost well with it so not sure it will help plumbing it back in for me..

    <tuffty/>
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  24. badger5
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    badger5 RIP S3dave Site Sponsor

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    yes, same as factory settings controls yes

    Consider the swing from std N75 operating duty cycle and target boost of standard to remapped tho.. Remapped is operating in a whole different range
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  25. Chlippo
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    Chlippo Member

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    Interresting...
    I like to have the forge manual one as its precise and i like the look.
    If i did understand well...can we remove the N75 and get an MBC instead? or there is a sort of bypassing?
    this wont be effective unless you have a modded car...i mean 270 + right?
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  26. Plunky
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    Plunky Member

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    I'm looking at using an MBC in series with my n75 to cut out some of the boost surges im getting.
    Where abouts would i plumb it in? between the acutator and n75?
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  27. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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  28. Plunky
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    Plunky Member

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    cheers mate! can you not put the mbc in series then? does it have to be parallel to the n75?
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  29. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    From what I have read then the way to control boost spikes is to run it in parallel... not tried it personally but I would advise having a quick google on the subject as this will help...

    <tuffty/>
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  30. Plunky
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    Plunky Member

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    just had a little read up on this.... appears that running the 2 in series only allows you to increase boost
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  31. Matt82
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    Matt82 Active Member

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    by the sounds of it, wouldnt any ko3 or ko4, even standard benefit from one? the boost spike and the way it tails off as standard is so stupid
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  32. badger5
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    badger5 RIP S3dave Site Sponsor

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    all depends on how the map is... if you log 118 block and see 95% or more its max'd out "shut" and turbo is flat out at that point
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  33. Plunky
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    Plunky Member

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  34. Welly
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    Welly VX220 SC Driver :)

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    Nope, thats a bleed valve - a totally different thing. Not good for engines with air flow meters.

    A bleed valve does what the name surgests, it bleeds a set (set by a screw) amount of boost away from the actuator. An MBC masks all of the boost until a set point (set by up by user again) using a ball and spring arrangement.
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  35. Plunky
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    Plunky Member

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    ah! thanks mate :D
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  36. Chlippo
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    Chlippo Member

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    why not just removing the N75 and getting a MBC like tuffty one.
    lol the engine might knock but then we know we have to lower the boost
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  37. Welly
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    Welly VX220 SC Driver :)

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    That's a bit of a risky arrangement mate to be honest.... I wouldn't do what we're talking about without supporting mods.

    If you're mapped, got rods and suitable VAG COM and engine knowledge then go for it! :thumbsup:

    If not, don't just slap one in and hope for the best - it has the potential to end in disaster. :(
    #37
  38. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Couldn't have put it better myself... I went logging straight after fitting my MBC to see what timing/boost/fuelling was doing....

    <tuffty/>
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  39. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    For the benefit of this thread here are some pics of the Forge UNOS MBC fitted to my car...

    [​IMG]

    ...and with the cover back on..
    [​IMG]

    <tuffty/>
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  40. Welly
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    Welly VX220 SC Driver :)

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    That looks really good dude, love the work on the install. Top work as usual. :thumbsup:
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