Spark Plugs

I remember reading somewhere that the duratec needed plat plugs because of the DIS set up it uses. Something about the waste spark going through the electrodes backwards or something. I can't remember because I read it so long ago, sorry. But if I were I'd wait a little longer to see what some of the tech advisors recommend.

I'm running copper plugs in my duratec. Motorcraft part # AGSF-22C

Originally posted by RocketFast321@Aug 8 2005, 01:33 AM
It's nice that people are searching for stuff. But the golden rule is.
If my engine came with copper, i will put copper back.
If my engine came with platinum, i will put platinum back.

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That's fine for stock applications, but when I put nitrous on the car everybody I talked to told me to go with copper plugs. I've heard that copper is a better conductor, and that the platinum tips have been known to break or break off under the increased heat and cylinder pressures.

When I first put the copper plugs in I was having some misfire issues, but I think that had more to do with the gap. Alberto told me to set them at .035 when the stock gap is .054, and this caused a misfire at high RPMs. Once I opened up the gap the misfire went away.

Originally posted by americanmotorsport.com@Dec 1 2005, 05:55 PM
Run copper.

Platinum is only used, as was mentioned earlier, because they last longer.

Copper is a much better condutor of electricity = better spark, all else being equal.

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"all else being equal" is the key phrase in that statement. On average, copper electrodes are about 2.5mm in diameter, platinum are about 1.1mm, and you can get denso iridiums with .4mm electrode diameter or ngk iridiums with .7mm electrode diameter. The smaller the diameter, the less voltage required to jump the gap.

http://www.densoiridium.com/spconstruction.php

Originally posted by Gaspare@Dec 1 2005, 06:06 PM
Silver is the best conductor of electricity, copper is second and then gold. Platinum is not very good at all because it has much more resistance even thought some manufacturers require it.

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A spark plug company called Brisk makes spark plugs with silver electrodes.

I can't reallly pinpoint whether or not the denso's helped me out because I did denso's, 9mm ford racing plug wires, and ported LIM secondaries all at the same time, and upgraded to 2ga battery cables shortly after. But, it definitely pulls a little harder after 4k rpm, it starts a little faster, and on a recent road trip I got a little better than 26mpg with an average speed of ~80mph(traffic permitting) and several (n/a) WOT runs into triple digit speeds and even a few lengthy stop-and-go traffic jams on the highway. Point is, it wasn't ideal highway travel, but I still got decent mileage.

But like I said, I don't know what mods account for what gains because I did them all pretty much at the same time.

What I have noticed is that with the plugs one stage colder than stock the car doesn't really run hard until after it's warmed up, whereas before with the stock plugs I'd get the best runs when it was still cold. :headscratch: