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NGK Iridium IX Spark Plugs


Relatively recent advances in fabrication techniques have enabled the use of Iridium - an incredibly hard precious metal, for the construction of spark plug electrodes. Laser technology is used to weld the Iridium tip to spark plugs manufactured NGK. It's worth noting that spark plugs can't increase the potential power that an engine can generate but a more efficient spark will provide more efficient combustion and associated performance and economy benefits. A poor spark from a worn or low grade spark plug will reduce efficiency. An Iridium plug will produce a more efficient spark.

Notable properties of Iridium are its melting point - approximately 2450 degrees C, considerably higher than Platinum, and it's strength - approximately 8 times that of platinum. The table below compares the characteristics of Iridium with those of other precious/semi-precious metals commonly used in the construction of spark plugs.



NGK produce a product range known as Iridium IX spark plugs. These are very high quality products using laser welding technology and NGK have perfected this process over a very long history of spark plug design and manufacture. NGK also manufacture OEM Iridium plugs, installed in some vehicles at the factory and usually having Iridium centre electrode and platinum chipped ground.

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's Iridium IX product range of spark plugs in the UK is aimed predominantly at the motorcycle market. There are a few instances of cars officially imported into the UK that use Iridium IX spark plugs as standard equipment - evidence that automotive manufacturers have tried and tested and now trust the product. keep stocks of the entire UK NGK Iridium IX range for immediate despatch and can obtain non UK spark plugs to satisfy most other requirements on request.

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.