Iridium: Hype or not?

You can also check for E3 Spark Plugs. I think they're EPA approved. Anybody ever tried them?

Hard to go wrong with NGK platinum plugs. Std equipment on the svx.

Don't know if it's true, but I read a piece from the company that makes the capacitor plug wires. They recommend silver plugs. According to them, the iridium and platinum plugs are intended to increase the replacement interval, not improve the spark quality. They said that silver is a much better conductor and better suited for plug tips.

Again, no idea if any of this is true.

Comments?

Philip

They also cure warts, improve your sex appeal, give your laundry whiter whites, add 50 more channels to your TV coverage, and...

Oops, got carried away there. I'm with Ed: the factory engineers are faced with the job of finding the best plug for OVERALL usage. So, even though there MAY be a situation that warrants something special, what came with the car is probably going to be hard to beat. Unless you just happen to like to tinker... which I liked to do a whole lot more before engines which are increasingly being set up where one can't even SEE where the plugs are, let alone get in there easily! Changing plugs has gone from "fun to experiment" to nothing but a chore.

Rick

Yeah. The extremely small difference in resistance of the various tip metals won't make *any* difference in performace. At 20-30 thousand volts, the millivolt drop at the plug tip would be unmeasurable. Simple Ohm's law.

Total marketing bullshit.

Plus, silver is far too soft to survive that environment and an application where arcs are needed.

-John O

Agreed.

I think ya nailed it, Jim!

Rick

Silver? There's a disaster waiting to happen. Them problem with silver is that it oxidizes far too easily at even room temps. And it would melt down under that kind of heat. There's a reason why spark plugs typically use nickel alloys/platings for the electrodes (as well as platinum/palladium/iridium).

Theoretically, annealed crystalline silver is the most conductive metal available. After that, it's annealled crystalline copper. Neither of these metals would make for a good spark plug electrode. Copper and silver might be OK for the plug core where it can be sealed from any oxygen and where it won't melt down. However - I can't see the point of using silver when copper is so cheap.

Untrue.

The important characteristics of the metal used for spark plug electrodes are high melting point, resistance to oxidation at high temperature, and electron emission. Resistivity is not a serious matter, as has been pointed out earlier--the current is quite low, and the path length is very short.

I recall from the good old days, that vacuum tubes used special coatings on the cathodes, to improve electron emission. However, with modern solid-state electronic ignition systems, the voltage available to fire the plug is so high that these things don't matter as much as they did in the good (?) old days.

The important characteristics of the metal used for spark plug electrodes are high melting point, resistance to oxidation at high temperature, and electron emission. Resistivity is not a serious matter, as has been pointed out earlier--the current is quite low, and the path length is very short.

I recall from the good old days, that vacuum tubes used special coatings on the cathodes, to improve electron emission. However, with modern solid-state electronic ignition systems, the voltage available to fire the plug is so high that these things don't matter as much as they did in the good (?) old days.

The important characteristics of the metal used for spark plug electrodes are high melting point, resistance to oxidation at high temperature, and electron emission. Resistivity is not a serious matter, as has been pointed out earlier--the current is quite low, and the path length is very short.

I recall from the good old days, that vacuum tubes used special coatings on the cathodes, to improve electron emission. However, with modern solid-state electronic ignition systems, the voltage available to fire the plug is so high that these things don't matter as much as they did in the good (?) old days.

My nephew collects old spark plugs and he has a couple that were advertised as radioactive, presumably to ionize the area around the electrode to increase electron emission.

Thanks to everyone for their input.

The E3 plugs are interesting but some report electrical noise with them. Rick's recommendation for standard NGK's makes a lot of sense (he's made tons of miles), but I hoped for something that doesn't need to be changed every 30k, or so. Seems like NGK platinums is the way to go for me.

MN

I have Denso IK20 iridium plugs in my MY02 WRX for 17,000 miles. There was definite improvement in pick-up under the turbo boost conditions, not much of that in NA mode (in comparison with stock OEM plugs). There was no noticeable change in gas mileage after switching to iridiums, if anything- very small drop. Spark plug replacement happened to be almost 4 hour exercise (because of tight space and fragile plug coil connectors) what used to be 45 min - 1 hr on Legacy. So , I am hoping for good longevity of iridiums not to do the very often. Although stock platinum plugs did not look bad after 30,000 miles...

I am enjoying experimenting with something new: iridium plugs, ceramic brakes, silicone wipers, but honestly, "old stuff" is just fine for majority of drivers. New toys bring mostly emotional value to some people, not that much of functional value.. Just my humble opinion.

Dave.