coldtændrør

A cold spark plug, or "koldt tændrør" in Danish, refers to a spark plug that operates at a relatively lower temperature within the combustion chamber compared to a hot spark plug. This lower operating temperature is primarily determined by the spark plug's construction, particularly the length and path of its central electrode's insulator. A shorter insulator and a more direct path for heat to dissipate into the cylinder head result in a colder spark plug.

The function of a spark plug is to ignite the air-fuel mixture in an internal combustion engine. The choice between a cold and a hot spark plug depends on the engine's operating conditions and design. Cold spark plugs are typically used in high-performance engines or those that operate under heavy loads or at high RPMs. In these scenarios, the combustion chamber experiences higher temperatures, and a colder spark plug helps to prevent pre-ignition or "knocking" by dissipating heat more effectively. If a spark plug becomes too hot, its tip can overheat, potentially leading to premature ignition or damage.

Conversely, hot spark plugs are designed to retain more heat. They are often found in engines that operate at lower RPMs or under lighter loads, where the combustion chamber temperatures are not as extreme. A hotter spark plug helps to burn off carbon deposits that might otherwise accumulate on the electrode, ensuring consistent ignition. The term "cold" or "hot" is relative and is indicated by the manufacturer's heat range rating for the spark plug.