Iridium spark plug specifications and benefits

There are currently two main manufacturers of Iridium spark plugs for automotive use available in the UK. NGK produce a product range known as Iridium IX and Denso produce Iridium Power spark plugs. Both are very high quality products using laser welding technology and manufacturing techniques perfected over a very long history of spark plug design and manufacture. Both manufacturers also manufacture OEM Iridium plugs, installed in some vehicles at the factory and usually having Iridium centre electrode and platinum chipped ground. Where an OEM Iridium plug is specified there is little to be gained by changing to an Iridium IX or Iridium Power plug. Champion have manufactured Iridium plugs for use in large industrial engines for quite some time but have not yet put any automotive parts into production.

Advantages of Iridium spark plug types

Due to the properties of Iridium, the spark plugs centre electrode can be made with a much smaller diameter than with platinum, Gold or gold palladium and copper/nickel types without sacrificing service life. The spark plugs potential difference is more concentrated at the tiny Iridium tip and hence less 'spark jump' voltage is required - this can be as much as 5,000 volts less than with standard plug types. Ignition is improved and less strain is placed on the ignition system. Benefits of improved ignition/combustion include better fuel economy, increased power/acceleration and especially better throttle response.

NGK Iridium IX spark plugs

Service life of some OEM Iridium spark plugs can be as much as 120000 miles with very little degrading of performance in that lifespan. NGK Iridium IX types have a centre electrode tipped with Iridium alloy with a 0.6mm diameter. NGK believe this gives the optimum balance between performance and service life. Service life estimates can be up to 60000 miles for normally aspirated car engines and up to 20000 miles for motorcycles - this is extremely subjective though, a high revving motorcycle or extremely modified car engine will most likely wear plugs out in a few thousand miles.