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Opus, et al.

        I have a friend who is a product engineer for NGK Sparkplugs. I
forwarded your question to him and his response is below.

                                Len

## Begin response


Good morning,

As to whether or not any of those new fancy plugs are better than current
ones, the answer is a bit ambiguous. It really depends on what the
application is.
For example, the new iridium spark plugs, with small diameter center
electrodes, are designed to provide several things:
        1.) Iridium spark plugs last longer than a normal nickel-plated
spark plug. The iridium is actually a very small disc (about 0.4mm in
diameter, and 0.001mm in thickness), that is welded onto the ground and/or
center electrode. What this harder metal does is prevent electrode wear and
gap growth, which is when the ground electrode begins to deteriorate, thus
incresing the gap, which requires more energy to jump the gap. Therefore, a
normal plug may last 30,000 miles or so in a car, and an iridium plug would
last about 70,000 to 100,000 miles, again depending upon the application.
        2.) Many new iridium plugs also have a thinner center electrode,
which provides two advantages: They require less energy to jump the gap, and
they can improve the flame kernal expansion rate. Basically, a thicker
center electrode and/or multiple ground electrodes provide more items on a
spark plug to get in the way of flame kernal expansion within a combustion
chamber, thusly not burning all of the fuel within the combustion chamber,
and then maybe not burning as efficiently. This is not always the case with
multiple ground electrodes, though, for it depends on the specific design.

Platinum plugs again provide long life to a spark plug. The disc is again a
very small platinum disc that is laser-welded onto the ground and/or center
electrode. However, platinum is not as durable as iridium, but is more
durable than your standard spark plug, so it falls somewhere in the 60,000
miles use range for cars, more or less. This again is dependant on the
application.

Multiple ground electrodes simply provide better anit-fouling capability,
for there is more surface area to cover before the spark plug becomes
fouled. Basically, multiple ground electrodes provide more options for
completing the circuit (jumping the gap). This may help during warm up of
the engine, where many vehicles foul their plugs. Once the spark plug
reaches its self-cleaning temperature, though, most of the carbon deposits
should be cleaned off of the firing surface.

Now, if you are asking about the "splitfire" type plug, the reality of the
situation is that they do nothing for an engine. The spark plug cannot
create any more energy than what is supplied to it by its ignition system.
If anything, a splitfire will simply work more like a multiple ground
electrode plug, and MIGHT give more fouling resistance. However, SPLITFIRE
plugs are made by AC DELCO (DELPHI), so they are basically a DELPHI plug
re-packaged as a SPLITIFRE. The ground electrode is the only differing
thing.

There are hundreds of custom types of plugs for racing, but they would take
a while to explain. To answer the question, though, it really depends what
you want the engine to do. I have heard that our (NGK's) new iridium plugs
do work very well, but have not as of yet had a chance to try them myself.

Just remember, that if you do purchase a new style of plug, to be ready to
do some carb calibration, especially if the firing end design, meaning the
physical structure, is different. I hope that this has helped.

Keep the rubber side down....

Trevor
Product Engineer
NGK Spark Plugs (USA), Inc.




Jeremy Witt
Field Engineer
Corrugated Networking Services Inc.
603-621-9099

- -----Original Message-----
From: owner-st@xxxxxxxxxx [mailto:owner-st@xxxxxxxxxx]On Behalf Of Rod Brown
Sent: Tuesday, December 14, 2004 8:13 PM
To: ST@xxxxxxxxxxxxxx
Subject: [ST] A fool and his money are soon parted

Over the years I have bought splitfires, surface gaps, two and four
electrode, platinum, even gold I think, spark plugs.  Used them in cars,
boats and bikes.  Now we have iridium plugs.  NGK's are about $7 each and
ND's are about $12 but they have a U-groove.   I have yet to get a single
mile per gallon out of any of plug or any perception of power increase,
although I did find that the splitfires didn't foul as much in my outboard.

Has anyone tried any of these iridum plugs and discovered mass quanties of
power or had problems with the gas tank over flowing on long runs????

Thanks,
Rod


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