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Thread: Different LS1 IFR's

  1. #1
    Senior Member Sid447's Avatar
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    Smile Different LS1 IFR's

    Why were there three different IFR tables {B4001} for the LS1 V8's that were made after 2001?
    In fact counting the 2001/2 Camaro there would be four.

    All of these engines were fitted with both the LS6 intake manifold and the LS6 28lb injectors, so were mechanically much the same.

    What effect would this have on the VE table and maf sensor frequency?

    By 2005 Holden switched to using the same IFR table that GM had been using all along since 2001 (in fact the 2005 and 2006 Holden factory tunes as a whole, had much more in common with the earlier GM tunes).

    Yet VE tables were still different and in spite of using the same 85mm maf-sensor in all 2005-on LS1 production, there were still differences in the maf-cal.

    Not so much an exact science, then? ....An example of more than one way to get the same result?

  2. #2
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    This has been pointed out in the past when someone insists there's only one way or one right way to skin this cat.

  3. #3
    Senior Member Sid447's Avatar
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    What effect,

    for example do the different IFR tables have. I notice early Holdens had the table starting at 3.55 and rising to 4.63 @ 80Kpa, with others starting at the same value and rising to 4.41. Does this have a direct effect on values in the VE table and also Grams/Cylinder {GM.DYNCLAIR_DMA}?
    In what way would they be different to the standardised LS1 values from 2005-on of 3.67 @ 0, rising linearly to 4.02 @ 80Kpa.

  4. #4
    Joe (Moderator) joecar's Avatar
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    For those to achieve the same wideband AFR during the same conditions using the same injectors, then the VE table will be directly affected.

    i.e. when IFR is bigger than injector's ability, the VE must also be proportionally bigger, this calculates a larger airmass which calculates a larger fuelmass.

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