two ignition ideas

[Chris Conlon]

Hi eveyrone,

A couple of people (on my other lists) have mentioned various engines
with 2 plugs per cylinder. (Not even counting rotaries, diesels, etc.)
Apparently in some designs the second plug fires much later, and helps
reduce emissions significantly. This led me to a couple of weird ideas
for ignition systems.

First, take a basically stock ignition system, and build a small
inverter to supply 3kV-5kV at a few mA, and a HV capacitor of hopefully
several hundred mF. Using some HV diodes, wire this in parallel with
the existing ignition system. The idea is to have the main spark fire,
and then have the inverter/capacitor continue a lower-current, long
duration spark across the now-ionized gap. (You'd need one per cylinder,
or some kind of icky switch, etc etc.)  Hopefully you'd get more
complete combustion, reliable ignition, maybe a bit lower emissions.

Has anyone tried this? The idea seems simple enough that I imagine
it's been tried and discarded for some reason or other. (No major
benefits over a well-done normal ignition, would be my guess.)


Second, something made me think that it would be clever/cool to use
short-wave UV light to ignite the charge. It generates ozone, after
all, which ought to ignite things nicely. I'm not sure how you'd
make part of the cylinder head transparent (a quartz glass plug?),
or how you'd generate the UV pulses reliably. (Some kind of solid
state laser is probably the only thing reliable enough that I can
think of. Are there long-life UV flashlamps?)  A drawback or
benefit is that the charge would no longer be ignited from a single
point, but rather a whole region would be ignited. You could
control this somewhat by altering how the light shines through
the port in the head. Would it be good or bad to have the whole
charge ignite at once? I have no idea. A likely benefit is
very thorough ignition/combustion, which is where the idea came
from in the first place.

Anyway, just a couple of wild ideas to stir things up.

   Chris C.