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'Re[2]: Spark Advance Help OT'
1998\06\15@112215 by Martin Green

    There are high performance electronic ignitions available that spark
    considerably more than twice for each power stroke (I don't know what
    the upper limit is but I've read of ones that fire at least 4-6
    times). To be effective they must use multiple ignition coils since
    the coil needs a finite amount of time to build up enough flux in the
    coil to generate a spark when dumped. This is different than the
    multi-coil setups in modern engines.

    The modern systems that use one coil for each 2 cylinders are used to
    avoid the need for a distributor, and have longer to build up the flux
    than the multiple spark units. They rely on the fact the when a given
    cylinder is ready for the power stroke (and spark), the opposing
    cylinder is ready for the intake stroke, and the spark going through
    the plug in this cylinder has no effect. It's kind of like those
    built-in pushbutton BBQ ignitors. One end of the peizo goes to the
    main burner spark gap, and the other end of the peizo goes to the side
    burner gap. Both gaps always spark when you push the button (at least,
    that is what is SUPPOSED to happen), but only the one with gas coming
    out has any effect.

    Incidentally, there is a new technique that seems to work even better
    than multiple sparks. In this system the cylinder is designed so that
    at the time of the spark, a sizeable air stream is flowing past the
    plug (perpendicular), which stretches the spark shape out to the side
    in a long arc. Much more gasoline than normal comes into contact with
    the spark this way. Initial test show considerably higher power,
    better fuel consumption, and especially important in these eco-nazi
    days, significantly lower emissions.

    CIAO - Martin.

______________________________ Reply Separator _________________________________
Subject: Re: Spark Advance Help OT
Author:  pic microcontroller discussion list <spam_OUTPICLISTTakeThisOuTspamMITVMA.MIT.EDU> at
Date:    6/12/98 12:07 PM

I believe that those engines that spark twice really only spark once.   The
just have two outputs (one spark plug on each end of the secondary
windings) so each
trigger fires two plugs simultaneously.

Problem with this is that one spark plug the center electrode is positively
charged, the other
negative.  Forget which way is preferred, but one of the plugs wears out
faster in the dual
firing/single trigger setup.

>The other problem (more serious imho) is more wear on the HV section (coil,
>etc).  If you're running 6000 RPM, that's 12000 sparks/minute on a 'normal'
>firing setup.  24000/60 = 800 sparks/second.  Not many non-racing ignition
>systems can handle that speed AND deliver a hot spark.

1998\06\16@073110 by Janet and Carl McIver

   I've been listening in on this thread with interest, and there is a
product that you simply replace your existing plug wires with these
"HotWires" and get a decent boost in all desired factors.  I created a
homemade version of these at the same time I found out about it.  On my car,
I never knew a TR7 with over three hundred thousand miles could have this
much power from the stock mill!  Check it out at
Well worth your time!

{Original Message removed}

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