Types of Spark Plugs
 

We see advertisements everywhere trying to sell us different types of spark plugs that all look different but claim the same thing, better fuel economy and more power. These are the faces of those plugs.

We start at the copper plug. The original spark plug.
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Copper is an excellent conductor of electricity but doesn't offer the life of most other plugs and needs changed every 15k miles. From what I've seen in my plug comparison photos of the plugs working under pressure, this plug doesn't offer any bigger spark than other metals with less conductivity.

A few copper variants have hit our market, the Chinese didn't like the low lifespan of copper and they created a plug that I don't think ever made it to mass production but looks interesting enough.

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We've all seen the splitfire.

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Not many of us have seen the Halo plug though.

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Or the E3 plug.

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A few designs have taken the idea of getting a nice and open path to the combustion chamber just a little bit further.

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A company in Mexico makes(made) this Technica plug. I've been unable to find them for sale online.

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The Torquemaster Plug is available online at a few places. This type of plug uses the surface-gap discharge method. Surface-gap gets its benefits because the spark takes less voltage to travel a long distance over the surface of the plug then it does to go through the air. This gives you more spark exposure area.

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A surface-gap discharge plug that is also long life is the Bosch Platinum +2 and 4 plugs.

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Then you have your typical Platinum plug.

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And your Iridium.

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Finally, you have the Pulstar plug. This plug differs from the plugs above by incorporating a peaking capacitor into the plug.

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Photos taken by me. Use them however you want.

Great photos! Have you seen the plugs with a pin hole drilled into the ground electrode? I forget the brand name, Sonic maybe? They have a small hole drilled directly in line with the electrode that you use to gap them, supposedly the spark takes place inside that hole and makes a smaller explosion first which in turn immediately ignites the rest of the cylinder more completely. I don't know how well they work but I have a drawing on how to make my own by drilling NGK's.

I've tried Bosch +4's, NGK's, Iridiums, platinums, U-Groove style, V-groove style, all kinds of expensive plugs, but none of them idle nearly as smooth as a cheap standard set of Copper Autolites. With the Autolites it runs so smooth that you can't feel anything at all even while in gear, but with any platinum or iridium plug it constantly stumbles and idles poorly in comparison.

The point I'm leading up to is the fact that with iridium or platinum plugs which conduct less, you are stuck using the factory gap setting to avoid misfiring. However with copper plugs you can very easily go with a much wider gap and still have acceptable idle quality, while at the same time gaining some fuel economy.

Chryslers and Fords I've had anything to do with all seem to like Champion Double Copper above everything else. 15K is a little short for a copper plugs life though, you can clean and regap them every tune up and get 60K+ out of them easy.

EDIT: LOL I didn't even finish reading the thread, I saw the Pulstar one at the end, my bad.

Nice photo work! I have an old issue of "Collectible Automobile" magazine which had an article on spark plugs, and the different types available back nearly a century ago...not much new under the sun!

You have one with two ground electrodes which looks just like the plugs they recommended for my Mazda RX2 back in the day.

Has anyone done any sort of controlled tests on all these different plugs to see just how they compare, performance and longevity?

More electrodes = more obstruction of the flame front.

More electrodes = greater chance of one breaking off and ruining the valves or piston. (not too likely, but could happen)

Therefore, single platinum electrode may be best, all else being equal (which it seldom is).