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Anyone familiar with the old Jacobs Electronic Ignition
systems (Ultra Team)?
It used to be only thing that kept my oil and fuel
guzzling Suzuki alive! If I changed back for the factory ignition the
engine would start to run on 3 cylinders in a very short time (2
min).
Jacobs claimed that his system used the sparkplug as a "
in cylinder"-sensor and that the computer in the system would adjust the spark
on the fly.
This way the voltage went way up for "ignition" :) and
then was reduced according to the requirements in the cylinder, so as to avoid
over current and too hot a spark. In his book " The Doctors guide to electronic
ignition" he mentions, that a spark can be too intensive and actually blow out a
recently ignited flamekernel. We are talking about the stage BEFORE the little
fireball reaches a diameter of 2mm, from where on it is considered a stable
combustion. Until that point things are not certain at all and missfires occure
in this stage.
He also mentions that it would be a breakthrough if it
would be possible to have a sparkplug gap of 2 mm to start the kernel at that
stable diameter, however at that gap the voltage would have to be so high, it
would be impossible to isolate the ignition parts in the confines of a
engine or engine room...
Jacobs sold the company (it is still called Jacobs
though...), but as far as I understand their systems use multiple spark now
(like MSD).
I imagine this kind of system would be great for the
rotary as the environment in the combustion area changes a lot and worse than
piston engines.
Does anyone know if there is a similar system on the
market (using the plug as a sensor and adjusting the spark
accordingly?)
Thomas J.
----- Original Message -----
Sent: Friday, December 03, 2004 11:15
AM
Subject: [FlyRotary] Re: (unshrouded plug
?)required wrench
They should work fine. I just felt that for a system set up for
maximum spark power, I didn't want to have a big resistance in the
plug. I have no idea whether you would ever notice the
difference. I expect Paul Yaw would.
The
resistor is there as a "ballast" to limit the peak current. You need high
voltage to strike the arc, but once the arc has formed, the resistance across
it is low and it takes very little voltage to sustain it. Without the resistor
in the plug, very high current flows, eroding the electrode and shortening the
life of the plug. Also, the high current produces a high magnetic field,
causing radio interference.
The
resistor also helps to increase the duration of the spark. There is a fixed
amount of energy stored in the coil for each spark. Without the resistor, a
high current flows. The energy is then quickly spent, resulting in a shorter
spark
duration.
Additionally,
you can "burn out" some types of spark plug wires by using non-resistor spark
plugs. The wire can't handle the extra current and goes open-circuit.
Most
cars have "magnetic suppression" type spark plug wire these days. It is a long
coil of thin wire wrapped around insulating fibers. It acts as an inductor in
the circuit. This tends to make the current much more constant during each
spark.
With
electronic ignition, it is not uncommon to have both magnetic suppression wire
AND resistor plugs. They act in concert to limit peak current, to smooth out
the average current, and to reduce radio (and computer) interference.
If the
coils and ignition control module you have selected were designed to use
magnetic suppression wires and resistor plugs, you would probably be smart in
continuing to use these type plugs and wires. The higher peak current from
non-resistor plugs can also damage the coil or ICM if they are not designed
for that use.
Just my
eight cents. :^)
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