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Wasted spark?

Discussion in 'Technical Q&A' started by fastradio, Aug 29, 2008.

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  1. fastradio

    fastradio F1 Rookie
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    #1 fastradio, Aug 29, 2008
    On your typical 1981 on 308, equipped with two Digiplexs, is there just one spark per cylinder revolution, or is there an additional "wasted spark" on the exhaust cycle as well...

    I'm working on some technical white papers, and need some addition insight as to the system's functionality..

    Thanks,
    David
     
  2. luckydynes

    luckydynes F1 Rookie

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    #2 luckydynes, Aug 29, 2008
    no waste spark .. . one spark per two cylinder revolutions
     
  3. smg2

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    #3 smg2, Aug 29, 2008
    yep yep, just one per rev, the Otto cycle is 720* :D
     
  4. fastradio

    fastradio F1 Rookie
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    #4 fastradio, Aug 29, 2008
    Last edited: Aug 29, 2008
    Maybe I'm just having a brain dead moment...but:

    I understand the Otto cycle
    And the 720* degrees to be back at TDC

    But...if we look at just one bank on the 308, and treat it as a 4-cyclinder engine and,
    There are two ignition triggers on the flywheel, with one trigger for each bank...

    Looking at this configuration, as in 720* of crankshaft rotation, the sensor "sees" the magnet on the flywheel...the Digiplex receives two triggers; hence fires twice...No?


    Ooooooops: Nevermind, I forgot about the distributor. Duh!!!!
     
  5. smg2

    smg2 F1 World Champ
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    #5 smg2, Aug 29, 2008
    OKay,
    I was mistaken on the previous post in the flywheel thread, the ECU does read the teeth count for rpms. it uses three sensors, bank 1~4 and bank 5~8 along with RPM. now I don't have the ECU 'flow chart' but I'd suspect it uses the crank angle computation based upon one cycle. the WSM shows the exact degrees the two sensors sit based on TDC of bank 1~4. there is no documentation that I'm aware of for the calculation of the system, but shouldn't be to hard to reverse engineer.

    an early version of crank & home signal but two banks instead.
     
  6. fastradio

    fastradio F1 Rookie
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    #6 fastradio, Aug 29, 2008
    Scott,

    I'm all set on this now...I just need to eat breakfast first, before I post these questions. Thanks for all the input.

    David
     
  7. Artvonne

    Artvonne F1 Veteran

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    #7 Artvonne, Aug 29, 2008
    Perhaps digiplex and functionality shouldnt be used in the same sentence, lol.
     
  8. fastradio

    fastradio F1 Rookie
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    #8 fastradio, Aug 29, 2008
    I should know better...Sorry!
     

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