I think that the whole multiple electrode craze is actually driven by the
federal government. They are having tighter and tighter emissions standards,
and ANY component that may potentially affect emissions must have a longer
service life. Right now I think that the feds want parts to last 100,000
miles.

So, if you are a car manufacturer, and you have to make a part that is a
wear item, which ultimately a spark plug is, last longer, you have to become
inventive. If one electrode will erode away well before 100,000, why not add
a second? If two won't make it why not add a third? Now you still have the
issue of the single center electrode. That is handled by the increasingly
exotic metals used for the electrodes (copper, then platinum, now iridium).

So, that gives us a situation where the large manufacturers have their
suppliers develop (or develop in cooperation with them) these plugs that
will last as long as needed. Once those suppliers have started making them,
and they have R&D money tied up in them, why not try to convince EVERYONE
that they need these plugs? It only takes a few more marketing dollars to
try to get more return on your R&D dollars.

Personally I think that perhaps the maximum number of electrodes I would
like on my own plugs is two. If you have many more than this, the spark is
going to become shrouded, and the fuel/air mixture will have a hard time
making its way to the spark and you won't get a good clean/complete/powerful
burn.

Any of you hot rodders out there remember the indexing washers for
sparkplugs? These were essentially shims that you would use to "aim" your
spark plug when installing your plugs in the head. When torqued, if your
plug wasn't at the optimum angle (spark not facing the most turbulent
fuel/air mixture), you pulled the plug out threw in one or two more indexing
washers and the angle of the plug could be aimed to optimize burn for most
power (they weren't worried about emissions in those days, but a better burn
is cleaner in this case).

I'm happy if I can get a good (preferrably Bosch) platinum plug with a
single electrode, but no more than two electrodes.

My 2�.

Cheers,
Bruce
motorbruce

>From: David Brodbeck <gull@GULL.US>
>Reply-To: David Brodbeck <gull@GULL.US>
>To: vanagon@GERRY.VANAGON.COM
>Subject: Re: vanagon single electrode plugs
>Date: Fri, 11 Jun 2004 15:07:04 -0400
>
>Aristotle Sagan wrote:
>>Can any one of you back up a single statement that you have made?
>>
>>I thought not. I put spark plug theories in the same catagory as DOT3/4
>>musings, holed cat superstitions, .91 Octane beliefs, etc., etc.
>
>Well, yes.  But I'd argue that considering that multi-electrode plugs
>didn't even exist yet when the Vanagon's engine was designed, its
>ignition system must have been designed to work okay with conventional
>plugs.
>
>To some extent I regard the multiple-electrode plugs as a scam; the
>spark will ionize the path of least resistance and all the current will
>go through that path.  It will never fork to multiple electrodes the way
>the Splitfire ads show it.
>
>--
>
>David Brodbeck, N8SRE
>'82 VW Diesel Westfalia
>'86 Volvo 240DL wagon