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Thread: Ambient Air Density and Manifold Air Density like Bank IDash

  1. #1
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    Ambient Air Density and Manifold Air Density like Bank IDash

    After reading about Bank IDash 1.8 and watching some youtube videos on how the Boost gauge is dead, I have had a play around with some User Maths parameters for VCM Scanner and I've had some success so I thought I'd share for anyone else interested.
    Reading Manifold Air Density (MAD) is far superior reading compared to manifold pressure or a boost gauge as it references a standard day.
    [15.5degC, 0% humidity, 101.32kpa baro]
    Here is some further reading:
    https://www.dieselarmy.com/engine-te...d-about-boost/
    Why the boost gauge is dead - Youtube

    Now since we don't have a humidity sensor we can't get an accurate reading of the air density so all comparisons are with humidity of 0%.

    aadmadbad.jpg

    This is a screen shot from my ute. You can can & paste these formulas into User Maths Parameters.
    On the bottom chart is:
    AAD - Ambient Air Density
    100*((([50032.91]*1000)/(287.05*([50008.241]+273.15)))/16.02*1000)/76.4
    MAD - Manifold Air Density
    100*((([50030.91]*1000)/(287.05*([50011.241]+273.15)))/16.02*1000)/76.4
    BAD - Boost Air Density
    (100*((([50030.91]*1000)/(287.05*([50011.241]+273.15)))/16.02*1000)/76.4)-(100*((([50032.91]*1000)/(287.05*([50008.241]+273.15)))/16.02*1000)/76.4)
    math.jpg
    This is an example so you get the idea....

    Its very interesting to observe whats happening in relation to Intake Air Temperature and the days barometric pressure.
    You would think because intake manifold pressure is 198kpa and boost is 14.2psi that I would have approx double the amount of air going into the engine.
    But when you take into consideration that the days ambient pressure is only 94% and the high intake temps (51C) that I'm only getting 80% increase in cylinder volume! Now if I had a decent water/air intercooler and I could get the air temps down to 9c then the MAD would be 200%!!!

  2. #2
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    Well done!!!

    Added to my scanner, getting the values but not the graph.

  3. #3
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    Very good stuff.

    Reading the last sentence always reminds me of this though lol. (not sure how many will get the picture though)

    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  4. #4
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    I have attached some files to help.
    Attached Files Attached Files

  5. #5
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    Quote Originally Posted by Hano View Post
    Well done!!!

    Added to my scanner, getting the values but not the graph.
    Can you be more specific of whats happening? Is it the chart on the bottom right not showing the trace? or can you share a screenshot? I forgot to add that you need to be logging these channels in the left column first.
    My ecu is a BF. It may not work on a BA. Should work on a FG though.
    I'll help you get it working if you want.

  6. #6
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    Okay
    Graph is working now
    So my MAD% is working 100%
    AAD seems constant , as it should
    But BAD seems to be not reacting and also constant straight line

    I cheched the Math parameters
    Will see if its running on the left hand

    Thanks

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  8. #8
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    Quote Originally Posted by Hano View Post
    Make sure you are also logging ambient air temp in lh column.

    I can see that you are missing the unit for AAT.
    Looking at the expression for that I can see an error.
    You have (50008.24) instead of 50008.241

    Cut and paste the formula again then you should see C Celsius for the unit.

    I've just upgraded my intercooler from a BF FPV factory cooler to a 600x300x100.
    I'm interested to do some comparisons to see how much improvement there is in air density.

  9. #9
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    Ah, Great !
    Got it in now and can see Celcius.

    I have a 450 X 300 x 76mm in
    With watermeth injection

  10. #10
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    Did a log today with the parameters
    Noticed my throttle position pegg at 74%

    image (2).png
    Last edited by Hano; 04-06-2019 at 06:37 AM.

  11. #11
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    Quote Originally Posted by Hano View Post
    Did a log today with the parameters
    Noticed my throttle position pegg at 74%

    image (2).png
    You're better off logging throttle angle in degrees. It should be around 80-82 degs at WOT. You can double check with the ignition on/engine not running.
    I've seen on my car throttle clipped to 75deg when torque is exceeded - usually trans truncation.
    Looks like you are putting a decent amount of boost pressure in there.
    You must be running on petrol? Spark advance is very low.
    Last edited by luke111; 04-06-2019 at 06:57 PM.

  12. #12
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    Yes 95 petrol
    Boost is 12 psi but it does over shoot on gear change, but for some unknown reason(torque management) spark goes into the negatives on change over, and I think thats why it over boosts there.
    I will look into this throttle angle thing.