Originally posted by DanCanuck:
What do you mean when plugs are described in
terms of "cooler" or "hot"?......
The heat range of the spark plug determines how hot it will get. The length and diameter of the insulator tip and the ability of the spark plug to transfer heat into the cooling system determine spark plug heat range.
A hot plug will have a long insulator tip that prevents heat transfer into the cylinder heads/water jackets. It will also burn off any oil deposits better. This provides a higher "self-cleaning" action.
A cold plug will have a shorter insulator tip and will operate at a cooler temperature. The cooler tip helps prevent overheating and preignition. (detonation)
A cold spark plug is used in vehicles that employ forced induction or nitrous & engines that have increased compression ratio, advanced timing, or are operated at high rpms & speeds for extended periods of time.
