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Old 06-07-2012, 09:18 AM   #14
Bacon117
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Member#: 118500
Join Date: Jun 2006
Chapter/Region: MWSOC
Location: Michigan
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Quote:
Originally Posted by Ralph47 View Post
If your not going to explain WHY one shouldnt, then dont worry about it.

I already got new NGK plats in the car waiting to be put in...
I would be happy to explain actually. I'm just curious as to why you believe they are superior.

A nickel spark plug, commonly called "copper" is inferior to an iridium or pt plug in EVERY measurable way, except price. The term copper is from the 1980's and 1990's when Champion trademarked the name "copper" for their standard nickel spark plugs. I believe back then, copper was NOT used in the first iridium spark plugs, probably to keep price down.

Today, all NGK spark plugs have the same amount of copper in the exact same configuration. I don't know about other makers. I'm 99% sure Denso does, and 70% sure Bosch does. I don't know as much about them, since I don't work there. However, any information I tell you can be used to understand plugs from any manufacturer.

So why copper? A spark plug has to be able to transfer enough heat from the tip so that it doesn't over heat. An over heated spark plug will damage an engine. This can occur at high engine loads. At the same time, a spark plug needs to stay warm enough at cruising speeds so it doesn't collect carbon, and misfire due to carbon fouling. Copper allows us to design the spark plug so that it acts like a hotter spark plug at cruising speeds, but can still handle heat at high load / high speed.

What does copper do for performance? Nothing. Copper only affects the temperature of the tip of the spark plug. The temperature of the center electrode does not affect engine performance at all. Unless it over heats... But that will not happen if you use the heat range that came with your car. Why do so many people believe copper is better? Advertising. Champion did a great job of selling their product 20-30 years ago, and people still believe those claims today.

I'm going to explain ignitability below, which has a lot to do with heat transfer, but over a different time scale. The copper transfers the most heat AFTER the spark happens, while the combustion in the chamber is occurring. Ignitability is heat transfer only just after spark, around 5-10 ms (milliseconds). I just want you to understand that while these are similar phenomenon (heat transfer), they happen on different scales, so one does not affect the other.

Why is iridium or pt superior?
1.) Ignitability: Iridium and PT have much smaller center electrodes. When the coil fires, and the spark occurs in the gap, a small flame kernel is initiated. Again, this is on a VERY small time scale. While this flame kernel is very small, any metal around it will absorb heat. Since the flame kernel is small, any heat absorbed will have an effect as combustion grows through the cylinder. The smaller electrode of an iridium or pt plug help to reduce this heat absorption. The less energy reduced from the flame kernal is more energy that makes it out to the cylinder, for a more complete burn of the fuel.
2.) Wear: This is one is simple. Iridium and Pt are MUCH harder elements than nickel, so they don't wear as easily.


And yes, as Uncle Scotty said, I'm an engineer (A test engineer to be specific), and I work for NGK. I AM the local expert on spark plugs. Don't believe me? Come visit me at the NGK headquarters in MI. Ask for Russell Senior. You can buy me lunch.
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