You need a new tuning shop then. Iridium do not fire more accurately, in fact that makes little sense. Platinum are better because the have a high melting point for longer life, it resists oxidation better (platinum's equivalent to rust), and it's a harder metal than than Nickel (standard plug) so they can get away with smaller center electrodes. Smaller electrodes, both center and ground, prevent what is called "quenching". When the flame kernel begins to develop between the electrodes, after the spark, it's growth is slowed because it has to go around the electrodes in order to expand. Larger electrodes = More Quenching = Less efficient combustion = less power. Iridium alloy is better in all 3 areas. The alloy is so much harder in fact that they can make a .4mm center which 1/2 the size of platinum and 1/6 the size of nickel electrodes. Denso, by the way, is the only company that figured out how to manufacture a center electrode so small, everyone else is doing .7mm. Thats a center electrode smaller that a mechanical pencil's tip. I should have called this thread "Sparkplugs 101" Simply put, this is how it is: Harder Metal = Smaller Electrode = Less quenching = more efficient combustion = more horsepower. And, Iridium is quite hard.
Last edited by animosity242; 08-01-2006 at 01:51 PM.