Spark plugs. Why is it so hard?
I haven't found the first thing that backs up any of that. In fact, all I can find is copper has the least resistance. Period. I'm all about learning and I'm the first one that'll admit I'm wrong, but so far I see no proof of it, but quite the opposite.
Resistance doesn't matter that much. We put 4k ohm resistors into spark plugs to kill RFI noise (and wires too, most have a pretty high resistance!).
*edit*
Turns out, the resistance also helps kill capacitive after-fire (a second spark after the initial spark, caused by the capacitance of the leads and spark plug body). Capacitive after-fire won't help an engine run better, but can wear electrodes faster. The resistance of plug wires and spark plugs also helps limit current through the ignition system to prevent burning out coils and distributors. Low-resistance wires are often marketed with hype about their low resistance, but in reality they simply add a highly conductive material that makes them 'measure' low, but in reality are not a significant part of the electrical path for the spark and therefore don't actually improve anything. But a lighter wallet does go faster, right?
*end of edit*
Low resistance won't do anything either since spark plugs and wires work on inductance not conductance. I'm not an EE, but I do know for a fact that resistance doesn't matter much if at all (until it's so high as to create an open circuit). High voltages overcome resistance quite easily, however it does it.
I'm trying to find the charts and graphs which show the change in breakdown voltage for spark plugs based on standard vs iridium, vs platinum. I know I've had several motorcycles which require iridium plugs because the charging system was too weak to keep copper plugs clean!
Here's at least one source, with quotes from Autolite's director of engineering, stating that the fine wire iridium plugs can reduce coil requirements by as much as 20% - which means by switching to iridium, one could open the spark gap considerably with a stock coil.
Also notable:
"Fine-wire iridium plugs can improve the combustion process even if there is a high level of exhaust gas dilution—built-in EGR—as with engines with long-duration camshafts with a greater amount of overlap."
