I will act the N00B here. Can someone explain cold plugs? What are they, what are the benefits, what to look for? How do they interact with thicker wires, etc.?

 

Well, I am hardly an expert on this stuff, but here it goes.... The colder plugs have a colder spark. This means that the plug won't cause detonation under hard driving conditions. It is recomended for pullied cars and high hp cars.

Also, if you do get a pair, I recomend the Denso IK-22s. They are the cheepest and IMO the nicest of the available parts. Get them direct from denso, or find some on ebay. They will be far cheeper than some of the vendors sell them.

 

From Wikipedia...
"If the tip of the spark plug is too hot it can cause pre-ignition leading to detonation/knocking and damage may occur. If it is too cold, electrically conductive deposits may form on the insulator causing a loss of spark energy or the actual shorting-out of the spark current.
A spark plug is said to be "hot" if it is a better heat insulator, keeping more heat in the tip of the spark plug. A spark plug is said to be "cold" if it can conduct more heat out of the spark plug tip and lower the tip's temperature. Whether a spark plug is "hot" or "cold" is known as the heat range of the spark plug. The heat range of a spark plug is typically specified as a number, with some manufacturers using ascending numbers for hotter plugs and others doing the opposite, using descending numbers for hotter plugs.
The heat range of a spark plug (i.e. in scientific terms its thermal conductivity characteristics) is affected by the construction of the spark plug: the types of materials used, the length of insulator and the surface area of the plug exposed within the combustion chamber. For normal use, the selection of a spark plug heat range is a balance between keeping the tip hot enough at idle to prevent fouling and cold enough at maximum power to prevent pre-ignition leading to engine knocking. By examining "hotter" and "cooler" spark plugs of the same manufacturer side by side, the principle involved can be very clearly seen; the cooler plugs have more substantial ceramic insulators filling the gap between the center electrode and the shell, effectively carrying off the heat, while the hotter plugs have less ceramic material, so that the tip is more isolated from the body of the plug and retains heat better.
Heat from the combustion chamber escapes through the exhaust gases, the side walls of the cylinder and the spark plug itself. The heat range of a spark plug has only a minute effect on combustion chamber and overall engine temperature. A cold plug will not materially cool down an engine's running temperature. (Too hot of a plug may, however, indirectly lead to a runaway pre-ignition condition that can increase engine temperature.) Rather, the main effect of a "hot" or "cold" plug is to affect the temperature of the tip of the spark plug."

Much more where that came from. Enjoy...
http://en.wikipedia.org/wiki/Spark-plug#Heat_range

 

Often a colder plug will be a bit shorter (not extending as far into the
combustion chamber) than a hotter plug. This provides a shorter path
for the heat to be soaked into the head, keeping it cooler and preventing
detonation.

 

If your car is stock then a colder plug is not needed. Some say that you should run a colder plug when you upgrade the pulley on the car. The colder plug allows for colder temp. in the motor. When you run more pressure into the car, the hotter the temp. will be inside the motor. To prevent any detenation, you can run a colder plug to keep things cooler hence colder plug. Eric at Helix suggest that the stock plugs are fine and would rather have the plugs go bad before the pistons or anything else on the motor if detenation were to occur. There is much info to be found on this forum. I suggest you read up as much as you can!

- Garrett

 

When I had my pulley done, I was told I didn't need colder plugs.

 

If you're not sure if you need colder plugs, just check 'em. If the tip is a nice yellow-white color, you're good. If they are black, you need hotter plugs.