P12.What is a surface discharge spark plug?

It is a spark plug designed to produce sparks along the isolator surface at the ignition end.

This spark plug type is also classified as semi-superficial discharge type and superficial discharge type.

 

 
Characterístics
 
Semi-superficial discharge type
The semi-superficial discharge type spark plug is designed to produce sparks along the isolator surface in the metal cover direction. The sparks burn the adhered coal, providing this way greater resistance against dirty.

Superficial discharge type
This spark plug has a smaller heat exposed isolator surface exposed and is a super- old spark plug; therefore, it gets dirtyy easily. To overcome dirty, a capacitor discharge system is used which reaches rapidly the required voltage to produce the sparks.
It is used in engines of high performance like the engines of Formula 1.