The interesting thing about ignition systems is that they will only produce
enough voltage to start the spark across the gap of the plug , then the
voltage tapers off VERY quickly cycling down to nothing . If you put a 10
million volt coil on the car and it only takes 10 thousand volts to jump the
gap then it only makes 10 thousand volts . Of course this makes for many
interesting arguments about whether a coil with more headroom is better , you
know Ohm's law makes the whole electrical situation a zero sum gain . You must
trade off amps for voltage , that's where a capacitive discharge ignition does
something different , by stepping up the primary voltage , several hundreds of
volts to the primary side of the coil instead of battery voltage , they can
increase the output of the secondary side of the coil . But only up to the
point that the spark starts across the gap , it still only creates enough
voltage to jump the plug , once the electricity starts moving it continues to
do so very easily . If you need 10 thousand volts then you'll get 10 thousand
volts . Some ignitions are able to expend their energy over a longer time than
others , which may be helpful , but they give up something in max voltage ,
which might be totally meaningless . I use a distributorless ignition that
uses stock GM coils , very high resistance plug wires , because the system is
very sensitive to RFI , and I shift the car between 8 and 9 thousand every
shift , this system probably produces thousands less volts than the CDI
ignition that I had , but this system made the single biggest improvement in
driveability of any component on the car . My conclusion , spark control is
much more important than spark energy . Control the spark as carefully as you
can , that will give the most return for your investment . That's just my
opinion .
Sorry for the long-windedness .
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