M&W (please, do you have a name?). Once again with regard to spark plug life, that is a function of CDI power. Too much spark power past a threshold causes excessive erosion of conventional spark plugs. I have coming on to 60 years of CDI experience from two generations that proves it and more recent experimental proof that explains why. Small engine CDIs(magneto type) aren't generally hard on plug electrodes either for the same reason. Sure, racing CDIs are going to be hard on plugs with the higher energy, and very efficient coils giving high spark powers. No question there. (although a few vintage racers are using my voltage limited CDI with success). I'm sure M&W makes a quality product built well for its intended purposes. However with regard to spark plug erosion, well yes, facts are indeed facts. Fred
Edit: By way of an explanation for those that really want to know, My CDI will erode spark plugs quickly if paired to a low inductance, low resistance 'CDI' coil. When paired with a conventional inductive coil, for which it is specifically designed to use, there is double or more resistance on the secondary winding. That's not a good thing but is easily worked around with enough applied energy, but that resistance does limit current to the spark gap. The second thing about an inductive coil is that after the spark gap breaks down and current starts to flow heavily, the large inductance acts like a series reactor to limit the peak current. That's a good thing because the inductance is not nearly as wasteful and actually stores energy in the magnetic field, a portion of which is given back to the system. So, using a conventional inductive coil for both the added resistance, and the series reactor effect, along with limiting the available energy, all work together to keep spark power below the erosion threshold. Fred
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Originally Posted by M&W Ignitions
Dannobee you are correct, there are a number of Top Fuel Harleys currently running our 1,000mJ Max system and more coming online. The results so far are showing significant improvements in combustion consistency and combustion quality.
Now that engines have moved away from distributors dwell is not so much an issue. Our systems were used exclusively for 15 years on the Australiain premiere V8 supercar class which which were a relatively high revving v8 and limited to distributor ignition at the time. Prior to this the inductive ignition started to run out of power above about 6,000 rpm where as the cdi used could maintain full ignition energy to just above 10,500 rpm.
We try not to voice opinions just facts, the reference made to spark plug life being a/the major limitation to OEM use came from Bosch engineers we were working with at the time. We have also seen significant plug life issue during our work on continuous running large stationary and heavy vehicle engines.
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