Iridium plugs to Copper?!?! Has anyone done this?

[Gokhan]

Originally Posted By: Gokhan
From what I read, iridium has higher ignition performance than platinum and platinum has higher ignition performance than standard (nickel). The general claim made is that the thinner the electrode, the higher the ignition performance is. The thickness of the electrode is limited by the melting temperature; so, iridium is the thinnest (highest performance) while nickel (standard plug tip) is the thickest (lowest performance).

One note: In standard spark plugs with thick electrodes, which decreases the ignition performance due to the cooling effect of the large electrode on the initial fireball, they employ tricks to improve the performance. DENSO uses a U groove so that the initial fireball can extend into the groove before the ground electrode cools it. NGK uses a V groove on the center electrode, which probably works similarly, and they also claim that it helps reduce the firing voltage, as sharp edges increase the strength of the electric field by those edges, causing the spark start there as the air ionizes due to the high electric field.

 

[Vikas]

People who are talking about resistance of Iridium, Platinum or Copper do not understand the ignition system. Next time when you have your plugs and wires handy, use a multi-meter to measure their respective resistance. Extra artificial resistance is added to the plug and/or wires. Smart people realize that the microscopic difference in the resistance value of the tip is completely immaterial.

The noble materials used in the tip of the plugs are chosen for their ability to resist erosion. Difference in the electrical conductance between the material is there to confuse people who skip science classes in the school These are the same guys who wants to apply "conducting grease" to their battery terminal. They are just hopeless.