spark plug cutaway

  the spark plug is quite simple in theory.it forces electricity to are across a gap,just like a bolt of lightning.the electricity must be at avery high voltage in order to travel across the gap and create a good spark.voltage at the spark plug can be anywhere from 40.000 to 100.000 volts

 the spark plug must have an insulated passageway for this high voltage to travel down to the electrode. where it can jump the gap and from there be conducted into the enjine block and grounded.the plug also has to witstand the extreme heat and pressure inside the cylinder. and must be desinged so that deposits from fuel additives do not build up on the plug 

spark plug use a ceramic insert to isolete the hiah voltage at the electrode, ensuring that the spark happens at the tip of the electrode and not anywhere else on the plug ,this insert does double-duty by helping to burn off deposits ceramic is atairly poor heat conductor.so the material gets quite hot during operation .this heat helps to burn off deposits from tne electrode

  some cars repurie a hot plug this type of plug is desingned with a ceramic insert that has a smaller contact area with the metal part of the plug .this reduces the heat transfer from the ceramic ,making in run hotter and thus burn away more deposits .cold plug are desingned with more contaet area so they run cooler

the carmaker will selact the right temperature plug for each car some cars with high-performance engines naturally generate more heat ,so they need colder plug .if the spark plug gets to hot it could ignite the fuel before the spark fire so it is important to stick the right type of plug for yor car