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Thread: Calculating Instantaneous Net Power

  1. #11
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    The calculated graph from efilive is smooth on the dyno, but when run on the street is very erratic... Get me now? .

    The way I see it is, since there are lot less variables on the dyno its easier to apply the force to the drum than to the street.. wheelspin? different waves of air?? maybe if instead of logging 24PIDs one logs 3 or 4 would get more frames per second and provide a much much smoother curve.

    With the AT123 V2 I am getting 9.4 frames per second... I got with more PIDs 10frames/s out of an OBDI!!!! So.. I dont understand.
    "All that is needed for the triumph of evil is that good men do nothing..."

  2. #12
    EFILive Developer Site Admin Blacky's Avatar
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    Quote Originally Posted by The Highlander
    The calculated graph from efilive is smooth on the dyno, but when run on the street is very erratic... Get me now? .

    The way I see it is, since there are lot less variables on the dyno its easier to apply the force to the drum than to the street.. wheelspin? different waves of air?? maybe if instead of logging 24PIDs one logs 3 or 4 would get more frames per second and provide a much much smoother curve.

    With the AT123 V2 I am getting 9.4 frames per second... I got with more PIDs 10frames/s out of an OBDI!!!! So.. I dont understand.
    Select "Generic" scan mode and only have a single PID (SAE.J1979.VSS} or {SAE.VSS} selected.
    You should get a frame rate of about 20 frames per second in V5, and up to 40 frames per second in V6.

    OBDI (ALDL) is way faster than OBDII - always will be.
    OBDII has too much overhead.
    Typical ALDL frame contains 4 bytes of header and 64 bytes of payload.
    Typical OBDII frame contains 6 bytes of header and only 6 bytes of payload.
    So the OBDII data transfer rate is effectively halved by the top heavy J1850 protocol.

    Regards
    Paul

  3. #13
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    The other thing is if I use the fast dynamic can I log faster using a lot less PID's??? LMK

    I want to beta test a v6, but have not gotten a response... is it possible to get ahold of a V6?
    LMK

    THanks
    "All that is needed for the triumph of evil is that good men do nothing..."

  4. #14
    Joe (Moderator) joecar's Avatar
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    I thought EFILive V6 was available in the download section of this website.

  5. #15
    Joe (Moderator) joecar's Avatar
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    Quote Originally Posted by joecar
    I thought EFILive V6 was available in the download section of this website.
    Oh, I was wrong, sorry. :oops:

    You may have to contact Blacky (Paul).

  6. #16
    EFILive Developer Site Admin Blacky's Avatar
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    Quote Originally Posted by The Highlander
    The other thing is if I use the fast dynamic can I log faster using a lot less PID's??? LMK
    THanks
    Fast dynamic is fixed at 24 bytes of data at 5 or 10 frames per second by the PCM. Selecting less PIDs just means reducing the number of data bytes - it does not increase the speed.

    Regards
    Paul

  7. #17
    EFILive Developer Site Admin Blacky's Avatar
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    Quote Originally Posted by The Highlander
    The calculated graph from efilive is smooth on the dyno, but when run on the street is very erratic... Get me now? .

    The way I see it is, since there are lot less variables on the dyno its easier to apply the force to the drum than to the street.. wheelspin? different waves of air?
    Here's two example charts showing Joe's hp calculations

    The first chart, from a dyno run, is a supercharged LS1 and is fairly smooth. The dyno was a hub mounted dyno which provided very fine speed control over the engine.



    The second chart, from a road run is a normally aspirated LS1 and is very erratic, during the run the rear tyres were "complaining" - they were on the limit of adhesion - maybe a little wheelspin.


    [/img]

  8. #18
    Joe (Moderator) joecar's Avatar
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    Paul,

    Hmmm.... :?

    On those 2 traces, expand the scales for VSS, RWHP, run time, and then replot with VSS and run time right above RWHP, and then repost (centre the traces around an upward slope mostly, and expand to fill most of the chart);

    Please send me a table of MPH vs time points for the linear upward portions of each trace; I'll do some approximate calculations on paper....

    Both traces seem to show the correct RWHP wiggles (matching the VSS wiggles), but the values seem too high.

    Like I said, "Hmmm.... :? "

    There's an explanation for "not-round", and we'll find it.
    Joe

  9. #19
    EFILive Developer Site Admin Blacky's Avatar
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    Quote Originally Posted by joecar
    Both traces seem to show the correct RWHP wiggles (matching the VSS wiggles), but the values seem too high.

    Like I said, "Hmmm.... :? "

    There's an explanation for "not-round", and we'll find it.
    Joe
    You were right Joe, the values were too high.
    V6 had a bug causing it to use kmh instead of mph
    (Thanks for finding the bug).
    So instead of calculating at 100kmh it was calculating at 100mph.
    I have updated the charts with the "correct" calculations.

    Paul

  10. #20
    Lifetime Member emarkay's Avatar
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    Paul, this would be a great "line item" in V6. A preset chart that uses this data and displays... Interesting idea....

    Preset modes for specific applicaions - not just a PID display, but a calculated representation of an event.....

    Or maybe It's too early in the morning for rational thoughts? :?

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