Thanks to Wicked for some really good information about spark plugs.
You've been on this forum for long enough, you should know by now that any thread on spark plugs will end up like this. There is simply too much half-science information out there on the subject, and too many theories and marketing without independent dynos to back up the claims. It's confusing to everyone. Even TurboTom's dyno tests were done on AR plugs, not A or AP plugs, and the gain was 4 hp not 5.
Your heat range information was mostly correct, although the reason colder plugs work better has more to do with low quality fuel and the high compression of our engines than the spark plugs themselves. Lower heat range plugs produce more power on low octane fuel because spark knock is decreased, timing is not pulled, and therefore you get more power.
There's also a difference you barely scraped on about what the short length of the back-strap. I'm only mentioning that because there are so many things that make up a good plug, or make more power out of a plug. Multi back-strap plugs, for example, are marketed as producing multiple sparks, but this doesn't jive with basic electrical theory of seeking the path of least resistance. What it does is offer more than one resistive path so that if one path becomes more resistant, spark goes to the lower resistant path. That would make these plugs more reliable in the long term.
Finally, nobody has mentioned that the actual conductor at the tip of every spark plug is neither copper nor silver in any case. It's always the same- a nickel/iron alloy. The difference is in the core itself. On the platinum/iridium side, most platinum plugs are copper core plugs with coated tips/back-straps. In a few cases, a small point of p/i is the center conductor. This offers a more reliable sparking point in the situation where fouling is reduced because of the metal used at the tip.
Now if everyone would please stop trying to make points that have already been made and sway everyone to your specific opinion. It's completely pointless and no e-thug is going to learn anything from another e-thug. It just ends up in horribly childish banter that doesn't promote anything but wasted bits on the server. I can't clean it up and delete everything that doesn't agree with the OP because that's a violation of free speech. Everyone has a right to their opinion, and everyone has a right to not change that opinion if they don't wish to.
The bottom line is that spark plugs are very important, and horribly misunderstood most of the time because there are so many factors besides the actual makeup of the plug. Companies out there who want to make a buck abuse this lack of general knowledge by promoting science half based in verifiable facts.
So who's going to start an oil thread now?
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