CD Ignition and its Superiority in Overcoming Shunt Resistances

Discussion in '206/246' started by Fred Winterburn, Dec 6, 2018.

  1. Fred Winterburn

    Fred Winterburn Karting

    Jan 27, 2015
    Carby, Your guess is as good as mine. I simply do not know. I have seen a haze around the main spark with powerful inductive ignitions firing through air but I always assumed that was the arc welder effect that occurs at low voltage once the initial high powered part of the spark event was over. You don't see this effect with a CDI in air, so maybe what you are seeing really is fuel igniting. I have no idea as that is way beyond my home grown testing ability. You will definitely get a much more intense spark with CDI by using a low inductance and low resistance coil. However, mine is designed to work best with some inductance as that prolongs the spark event at the expense of some lost energy and spark power. Some resistance is necessary too with mine to keep the switch from going up in smoke if someone selects the unit to STD. I have not tested the Crane unit but I have tested the older analogue MSD 6 CDIs. Those have a short duration spark of about 40µS with a full 1mS pause between spark events. IMO that 1mS is too long to be of any benefit above idle rpm. Fred

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