Plugs
#3
5 min of searching.
https://www.miataturbo.net/forum/t29001/
#4
Elite Member
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Go make a thread in the meet and great before your thread gets locked and you get banned.
5 min of searching.
https://www.miataturbo.net/forum/t29001/
5 min of searching.
https://www.miataturbo.net/forum/t29001/
I specifically read that thread and saw people using both. I didn't know if my lower boost would push me one way or the other.
I sure hope it didn't take you five minutes to find it. You started it!
Besides, you can't ban me yet. Only five people have paid for more frame rails. Let a few more pay before you do that!
#11
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IMHO, run stock or one step colder. One step colder will help prevent any chance of pre-ignition while not going too cold and sacrificing the plug itself and any chance of a weaker burn/ignition from pulling out too much heat.
The heat range is selected for two reasons: maintaining a high enough temperature tip to prevent fouling and removing heat from the chamber.
#12
true dat.
IMHO, run stock or one step colder. One step colder will help prevent any chance of pre-ignition while not going too cold and sacrificing the plug itself and any chance of a weaker burn/ignition from pulling out too much heat.
The heat range is selected for two reasons: maintaining a high enough temperature tip to prevent fouling and removing heat from the chamber.
IMHO, run stock or one step colder. One step colder will help prevent any chance of pre-ignition while not going too cold and sacrificing the plug itself and any chance of a weaker burn/ignition from pulling out too much heat.
The heat range is selected for two reasons: maintaining a high enough temperature tip to prevent fouling and removing heat from the chamber.
If you compare the amount of energy from the sparkplug sparking that goes into heat (some % of the total energy, dunno how much) and compare that number to the amount of energy released during the combustion process, it's hard to fathom that the ignition system could affect the fouling-ness of a plug. But I dunno.
It's my experience that plugs get fouled from running rich and cold. If you drive hard, I'd run 7's no question. If you drive it easy often and it runs rich, you could get some buildup on the plug. But I certainly wouldn't gauge what plug to get by thinking "I wonder if it will detonate with this hot of a plug" but rather, "I wonder if it will foul with this cold of a plug". Because I can't see the heat range of the plug really affecting performance.
#16
Originally Posted by NGK Website
Heat range
The term spark plug heat range refers to the speed with which the plug can transfer heat from the combustion chamber to the engine head. Whether the plug is to be installed in a boat, lawnmower or racecar, it has been found the optimum combustion chamber temperature for gasoline engines is between 500°C–850°C. When it is within that range it is cool enough to avoid pre-ignition and plug tip overheating (which can cause engine damage), while still hot enough to burn off combustion deposits which cause fouling.
The spark plug can help maintain the optimum combustion chamber temperature. The primary method used to do this is by altering the internal length of the core nose, in addition, the alloy compositions in the electrodes can be changed. This means you may not be able to visually tell a difference between heat ranges. When a spark plug is referred to as a “cold plug”, it is one that transfers heat rapidly from the firing tip into the engine head, which keeps the firing tip cooler. A “hot plug” has a much slower rate of heat transfer, which keeps the firing tip hotter.
An unaltered engine will run within the optimum operating range straight from the manufacturer, but if you make modifications such as a turbo, supercharger, increase compression, timing changes, use of alternate racing fuels, or sustained use of nitrous oxide, these can alter the plug tip temperature and may necessitate a colder plug. A rule of thumb is, one heat range colder per modification or one heat range colder for every 75–100hp you increase. In identical spark plug types, the difference from one full heat range to the next is the ability to remove 70°C to 100°C from the combustion chamber.
The term spark plug heat range refers to the speed with which the plug can transfer heat from the combustion chamber to the engine head. Whether the plug is to be installed in a boat, lawnmower or racecar, it has been found the optimum combustion chamber temperature for gasoline engines is between 500°C–850°C. When it is within that range it is cool enough to avoid pre-ignition and plug tip overheating (which can cause engine damage), while still hot enough to burn off combustion deposits which cause fouling.
The spark plug can help maintain the optimum combustion chamber temperature. The primary method used to do this is by altering the internal length of the core nose, in addition, the alloy compositions in the electrodes can be changed. This means you may not be able to visually tell a difference between heat ranges. When a spark plug is referred to as a “cold plug”, it is one that transfers heat rapidly from the firing tip into the engine head, which keeps the firing tip cooler. A “hot plug” has a much slower rate of heat transfer, which keeps the firing tip hotter.
An unaltered engine will run within the optimum operating range straight from the manufacturer, but if you make modifications such as a turbo, supercharger, increase compression, timing changes, use of alternate racing fuels, or sustained use of nitrous oxide, these can alter the plug tip temperature and may necessitate a colder plug. A rule of thumb is, one heat range colder per modification or one heat range colder for every 75–100hp you increase. In identical spark plug types, the difference from one full heat range to the next is the ability to remove 70°C to 100°C from the combustion chamber.
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