Splitfire plugs (was Ig. Book)

[Danny Wallace]

Steve Ravet writes:
>The fact that the electrode is split makes no difference.
>Only one arc will form.  The only way to get simultaneous
>arcs would be to  have two wires, and either two coils or a
>single dual output coil.   Otherwise the arc (like humans :-)
>will take the path of least resistance.

Steve,
In an attempt to gain vital (if only minute) increments in HP I
tried a set of these plugs in my Formula Vee (Aussie version).  I
didn't have two wires/coils or a dual output coil.
As I expected, I was not knocked over by any performance
increase.  The (race) circuit we tested on was about 3 km long
with 13 turns.  I would have thought the plugs were good for a
few tenths at least over that distance. 
We were unable to measure any difference in lap times.  Thats not
to say there were none, just that we couldn't measure any due to
other factors - eg driver inconsistency, lapped cars etc.  After
using the plugs I decided to pull one out and run the motor with
the plug resting on the crankase.  To my amazement the arc
occasionally DID fire simultaneously to both "sides" of the
elctrode - forming a bright "V".  I saw it with my own eyes! 
What puzzled me slightly though, was the inconsistency with which
it occurred, about 1 in 10 or 20.  I also wondered if this arcing
was only occuring at 1 in 10, with motor idleing (best case for
coil energy build up), then when running with higher revs and
cylinder turbulence, what would happen then?

One of these days I pland to build an ignition test bench.  Any
body else done this ?

Still wondering...
Danny Wallace
wallad at devetwa.edu.au