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Thread: ignition values in Tunecu

  1. #1
    apriliaforum Member laszlo__'s Avatar
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    ignition values in Tunecu

    Dear All,
    Hope a wise internal combustion expert can answer my question.
    Any of the tune maps let it be Futura or Caponord, shows lower and lower ignition advance values as the engine load increases.
    In my understanding as the engine load increases, more and more fuel injected into the combustion chamber and more fuel requires higher ignition advance to perfectly burn up all of the injected fuel in time. It means, the spark discharge must happen sooner before the TDC.

    Contrary Tunecu shows less and less ignition advance as the load increases. (Not the rpm !!)
    Can somebody give me explanation for this phenomena?
    60 V2 ..... best ever.....

    2013- APRILIA ETV1000
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  2. #2
    apriliaforum prov-nov Kennibear's Avatar
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    Under partial load the mixture in the combustion chamber is not as easily lit. But under high loads (maximum volumetric fill) the mixture is just about ready to detonate/diesel anyway so the flame front moves away from the spark plugs pretty fast. Lower loads the flame front proppagates much slower so the ignition needs to be advanced. Ford's early stratified charge experimental engines used something like 60 degrees BTDC to light off.

    KB

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  3. #3
    apriliaforum expert brmbrm's Avatar
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    1950's and 1960's bikes had an ignition retard lever to retard the ignition when under high load eg full throtle hill climbimg.
    To prevent pre-ignition/knocking.
    I assume this is a digital version of that.
    My name is Dave,
    bike's name is Black Betty.

    When you're traveling, you are what you are right there and then.


    Caponord - Douglas Dragonfly - 1942 Harley back again
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  4. #4
    apriliaforum expert catfish's Avatar
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    Low-density mixture (1/8 throttle) burns slow; needs more advance. High density (WFO!) burns fast, so needs less advance.

    Goal is always peak combustion pressure just after TDC.


    Catfish ...

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