Can someone explain to me the deal of spark plugs and their heat ranges?

 

Engines convert heat to mechanical power. Stock engine will have a compressions ratio (CR) and plugs with a heat range. Heat range is chosed so that plug remains at a specific temperature, so that deposits are burned on the plug, and so that it does not serve as a hottest source in the cumbustion chamber. When you increase CR, either by altering compression ratio, advancing timing, or increasing boost, more heat is converted to power and less heat escapes. If we increase CR and leave heat range the same, plug will retain more heat and be a source of heat in the combustion chamber, causing preignition. A plug with lesser heat range will retain less heat, and thus prevent preignition.

If heat range is choose too low for a given CR, plug will be build up deposits, spark will have hard time firing.

 

This should give ya a good understanding...


http://www.densoiridium.com/heatranges.htm

Jim