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Question regarding 3" MAF conversion

Discussion in 'A4/S4 forum(B5 Chassis)' started by B5QUAT, Aug 1, 2011.

  1. B5QUAT
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    B5QUAT Member

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    [Aug 1, 2011]
    Just been looking at FMICs in readiness for the big turbo conversion.

    A few of them seem to have 2" or 2.25" pipework. This got me thinking.

    Part of the GT28RS conversion uses a bigger 3" MAF housing but then surely reducing to a 2" pipe for the intercooler will create quite a restriction???? Don't know what diameter the throttle housing is.

    Do I need to be looking at and intercooler with 3" pipework to maintain the diameter as wide as possible for the GT28 to flow as well as it can?

    If anyone knows anything about this, be grateful to get a discussion going before I but the wrong darn cooler!
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  3. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    [Aug 1, 2011]
    Iirc the throttle body is 2.75" same as the oem MAF
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  4. Bradderz_1988
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    Bradderz_1988 Dont replace it, Upgrade it !!

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    [Aug 1, 2011]
    2.25 should be good for the gt28 the exducer is around 1.5 or 2" so your not creating any flow restriction up to the throttle body, you need a big core cooler for better flow with say the 2.25" pipework.
    Last edited: Aug 1, 2011
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  5. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Aug 2, 2011]
    well the first point is that the OEM MAF maxes out somewhere around 180-200g/sec, so 230-250hp. If you want more power you need a larger housing so the sensor can actually measure it.

    The second is that the intercooler pipework is all under pressure, ie its being forced along. Whereas the MAF is not.

    That said, larger pipework isnt going to hurt, and removes the potential for the small pipes causing a flow restriction.
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  6. B5QUAT
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    B5QUAT Member

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    [Aug 2, 2011]
    Ah, of course! d'oh! Now that makes sense. Thanks.

    I'll try to get one with the largest pipework I can find, as you say, so as not to cause a potential restriction. 2" seems way too narrow.

    Some I've seen have 2 solid pipes whereas others have 4 and more joints. The latter would seem better to me from a fitment point of view as these kits never look to fit 100% like they should.
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