HELP!! new plugs arn't iridium!!
Here is why i ALWAYS suggest running NGK Irdium ix BPR7EIX or heat range of 8 or 9 or whatever your set-up requires........
The real answer is the plug's electrode tip. You want to have the sharpest edge for which the spark to jump the gap from the electrode to the ground strap.
Too sharp a tip will melt the electrode. If the temperature of the tip reaches the melting point of the metal that it's made of it will no longer be there. Here are the melting points of some commonly used metals (Celsius):
Zinc == 420
Aluminum == 660
Copper == 1083
Steel == 1400-1500
Platinum == 1772
Iridium == 2410
This problem is mainly concerned with the volume of metal at the spark tip - if the temperature even instantaneously reaches the melting point, some of that metal will disappear. You can see that Platinum and Iridium coated plugs can withstand significantly higher temperatures, and thus can have sharper tips than their steel or copper counterparts. To add insult to injury, if some of the metal does disappear from a very sharp tip, then you've actually opened up the spark gap some. To prevent that from happening, we have to start with a wider tip, such that any small amount that is eroded will not change the size or geometry of the tip by too much.
To avoid this, we want a wide area near the tip to conduct as much heat away from the tip as possible. Here are some of the thermal conductivities of some commonly used metals (Watts / centimeter*Kelvin) :
Zinc == 1.16
Aluminum == 2.37
Copper == 4.01
Steel == 0.70 - 0.82
Platinum == 0.716
Iridium == 1.47
You can easily see why Copper is the metal of choice for the core of the spark plug. It's just about the best thermal conductor on earth. Occasionally, you still find plugs with an aluminum core - stay away!
So, what we want is the sharpest tip possible such that it does not melt the electrode nor does it stay so hot as to cause pre-ignition.
High boost applications running copper tip plugs will suffer serious plug wear at a very fast rate.
Running a fine iridium tipped plug requires less voltage to spark.
Also, start gap large and work your way down... don't just gap them to .026 like some people will tell you. All engine's and set-ups are different.
This can be seen here: https://www.evolutionm.net/forums/sh...7&postcount=29 To get a better grip on what i was saying, read the whole thread found here:https://www.evolutionm.net/forums/sh...light=plug+gap
If you have any questions....ask me.
CJ
The real answer is the plug's electrode tip. You want to have the sharpest edge for which the spark to jump the gap from the electrode to the ground strap.
Too sharp a tip will melt the electrode. If the temperature of the tip reaches the melting point of the metal that it's made of it will no longer be there. Here are the melting points of some commonly used metals (Celsius):
Zinc == 420
Aluminum == 660
Copper == 1083
Steel == 1400-1500
Platinum == 1772
Iridium == 2410
This problem is mainly concerned with the volume of metal at the spark tip - if the temperature even instantaneously reaches the melting point, some of that metal will disappear. You can see that Platinum and Iridium coated plugs can withstand significantly higher temperatures, and thus can have sharper tips than their steel or copper counterparts. To add insult to injury, if some of the metal does disappear from a very sharp tip, then you've actually opened up the spark gap some. To prevent that from happening, we have to start with a wider tip, such that any small amount that is eroded will not change the size or geometry of the tip by too much.
To avoid this, we want a wide area near the tip to conduct as much heat away from the tip as possible. Here are some of the thermal conductivities of some commonly used metals (Watts / centimeter*Kelvin) :
Zinc == 1.16
Aluminum == 2.37
Copper == 4.01
Steel == 0.70 - 0.82
Platinum == 0.716
Iridium == 1.47
You can easily see why Copper is the metal of choice for the core of the spark plug. It's just about the best thermal conductor on earth. Occasionally, you still find plugs with an aluminum core - stay away!
So, what we want is the sharpest tip possible such that it does not melt the electrode nor does it stay so hot as to cause pre-ignition.
High boost applications running copper tip plugs will suffer serious plug wear at a very fast rate.
Running a fine iridium tipped plug requires less voltage to spark.
Also, start gap large and work your way down... don't just gap them to .026 like some people will tell you. All engine's and set-ups are different.
Originally Posted by iTune
i would actually recommend started with a larger gap. try .032 first, then gap down from there if you run into mis-fires.
You want to run the largest gap possible to properly expose the spark to the mixture. If you run too big, the spark with actually be blown out, causing misfires, if you run too small, the firing end temp increases, thus does the cylinder temps/pressures. Rule of thumb is to start larger and work your way down until you no longer have misfires. Trust me on this. All engines are different, the gap requirements will change from engine to engine, setup to setup.
Heat range will effect a lot as well, the colder the heat range, the more fouling becomes a problem, make sure your set-up warrants a colder heat range plug. Look at my original post on page one for refference.
You want to run the largest gap possible to properly expose the spark to the mixture. If you run too big, the spark with actually be blown out, causing misfires, if you run too small, the firing end temp increases, thus does the cylinder temps/pressures. Rule of thumb is to start larger and work your way down until you no longer have misfires. Trust me on this. All engines are different, the gap requirements will change from engine to engine, setup to setup.
Heat range will effect a lot as well, the colder the heat range, the more fouling becomes a problem, make sure your set-up warrants a colder heat range plug. Look at my original post on page one for refference.
If you have any questions....ask me.
CJ
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