Spark Plugs

[mike tipton <mtipton@netten.net>]

Joe, nice acticle on the plugs.
My biggest problem with the Platinum plugs(platinum tipped version) is
my ignition puts out alot of voltage to the plugs.  Namely about +60K
worth of voltage.  The platinums start "erroding away" because of the 
high voltage of my system. As it was explained to me by Dr Hiereth of MB 
AG, "The High voltage's actually blast off microscopic pieces of the 
electrode, each time the plug fires. Resulting in errosion of the 
electrode, or a charectoristic "rounding off" of the electrode. The 
higher the voltage, the faster this errosion takes place.

The problem for me is the platiniums have such a "small electrode"
and this makes them only last about 500 miles with my ignition system.

I have actually found the Bosch Silvers, with the 22% larger electrode,
to work better and last longer, in my setup.  At 99cents each I have no
problem changing them often.(They usually go with the oil at 3K)

Now the Bosch Platin plugs at $25-$30 each is something I cant see 
buying, unless I could return them if not completly satisfied!! 
Wondering if my ignition setup would "eat" them also. At $150 to start
the I5, I can buy 150 Bosch silvers and have enough plugs to last for 
six years. Figuring a change of plugs each 3K miles, thats 15K a year,
5 changes a year, 25 plugs a year!

I run a Jacobs Ignition, have been for years, and have had no problems
with it except the plug errosion. Thats probably why in Dr Jacobs book
he reccommends the use of "iron core electrode" plugs such as AC Delco.

The closest I've come to AC is their rapid fire plugs. They work well
last as long as the silvers, but cost $4 each (4 silvers). So I stick
with the silvers for frugality.

I originally bought the Jacobs to facilitate the use of a super charger
setup I once ran on my Audi. It was a "projact" of sorts, to see if 
a retro fit "kit" would be viable for market.  I believed it was an
excellant setup. It ran superbly for two years with no problems.
The down side, at the time a very small Audi aftermarket, and cost was
too high to make it a seller in open market.

My "partners" pulled the plug(and financing) along with the super 
charger, so I was left with a stock motor and a Jacobs(I bought the 
ignition system). It found its way to all sorts of "projects",
including a "twin turbo" setup I5.  When the motor went "south"
the Jacobs still worked fine. Its adopted the "family airloom" status
with me.  Some archeoligist will probably find it in my tomb, a thousand 
years from now!

                                        M