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I've debated on how much information I should give towards this topic.
Knowing how the fuel mixture interacts with the spark and all the variables
that influence the spark is somewhat lengthy, but really understanding it
helps to see why upgrading the ignition can provide improvements.
Since I am by no means an expert in this and giving brief explanations
would likely spark more inquiries AND everyone is probably tired of seeing
this dead horse get badly beaten I recommend reading the publication by Dr.
Jacobs. It's called "The Doctor's Step-By-Step Guide to Optimizing Your
Ignition" by Dr. Christopher A. Jacobs, Ph.D, E.E., part no. 800001, cost
is $19.95 (I believe) and can be ordered by calling 1-800-627-8800. Even
if you don't buy any thing else from his company I still recommend buying
the guide as it explains what you need to know about ignition. I found it
to be good reading.
Briefly, about Dr. Jacobs, so you don't think he just did this as some
project and doesn't know squat about cars:
-Put himself through undergraduate studies working as an auto mechanic.
-Previously employed as a technical consultant to racing teams in
drags, Nascar oval and off-road.
-Formed Jacobs Electrical Products in '74 becoming the leader in
ignition products and considered the world's foremost expert in his
field.
-Still acting as a consultant with many top race car drivers.
-Holds the most worldwide patents for high performance ignition systems.
FYI: All the components he sells are approved by C.A.R.B (California Air
Resources Board) so they don't have to be used for off-road only like some
ignitions are sold as!
How does the computerized ignition system work? I'll be brief:
It has a variable-magnetic core (basically the coil part) that allows
computerized current adjustment and literally uses the spark plug that's being
fired as a sensor. The computer reads the resistance across the plug gap and
adjusts the current to the plug (the resistance of air and the resistance of the
ignited fuel mixture are very different!). In 1 1/2 degrees of engine rotation
the computer takes about 33 readings from the spark plug. It adjusts the
current as necessary to provide the 'perfect' spark during this rotation. Due
to *constantly* changing combustion chamber conditions the computer basically
forecasts what the necessary spark should be. On average 18 adjustments are
needed to create the proper spark for the particular chamber environment. Since
it is computerized the processes are happening in nanoseconds (i.e. super-duper
fast :) The computer also measures the watt-seconds of the spark and once the
plug has fired it performs a reverse firing for the same watt-seconds. This
procedure redeposits metal particles back on the electrode so the plugs will
last longer. Another benefit of reversing the current is that it (basically)
scrambles the molecules in the ignition wires which allows them to keep their
insulative properties longer than normal. You cannot burn carbon off of your
plugs like some may think, only a strong current can rip the deposits off. The
computerized ignition does this like other higher performance ignitions but
without lessening the life of the plug. Timing is still controlled normally by
whatever setup the car has (electronic or stock points and the dizzy). There
isn't a need to screw with timing, though a computerized system can allow for
the user to change it. It's all self-contained; there's no need for computer
skills. If you can operate a screwdriver or give the instructions to a mechanic
then you're set!
I hope this helps. For everyone's sanity please send additional queries
directly to me unless you feel it really should be seen by all. However, please
don't ask me to go into detail about the ignition process -- I'll get massive
cramps in my fingers 'cause of all the typing it'll create ;p
Toby Erkson
air_cooled_nut@pobox.com
modified '72 VW Squareback 2.0L
stock '75 Porsche 914 1.8L