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The higher the pressure in the cylinder, the greater the
dielectric strength, which means it will take a higher voltage to jump the gap.
Get the pressure high enough and the spark can't jump it, but if there is any
weakness in the plug wires, contaminated cigarette in the plug, or a
better breakdown path in the mag rotor or coil windings, there will be a
mis-fire. That's why rough-running sometimes occurs at full throttle. With
sparks jumping the rotor or the coil windings, there can be carbonizing paths
that will eventually cause mag failure! That's why it is necessary to
pressurize the magnetos and use the H-version plugs with the wider well at
higher altitudes. One thing that hasn't been mentioned yet is that once the plug
fires, it takes 1/6 to 1/8 less voltage to jump the gap. In the Plasma II,
with bi-polarity sparks lasting 20 deg. , that should provide plenty of
over-lap for the lower gap breakdown-voltage resulting from the
ionized gases at the other plug for the mag to fire into. BTW.
Klaus' Plasma has been approved in France for a production heli. Watch for the
press release!
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