Denso Iridium high performance spark plugs for the Maserati Quattroporte. 

Set of 8. 

By harnessing the power of Iridium, DENSO is suddenly able to shrink the surface area of the centre electrode - the critical component of a spark plug. Unlike a typical platinum plug that has a 1.1mm diameter centre electrode, DENSO Iridium Power plugs have the world's smallest centre electrode measuring 0.4mm in diameter. This means that the voltage requirements are decreased while firing performance is greatly improved. 

The patented U-Groove design changed the industry standard in the mid 1970s by providing a better design that virtually eliminates erratic starts caused by poor fuel mixture. The U-Groove results in less flame dissipation making the spread of the flame nucleus easier and therefore yielding greater firing energy. It gives the flame a groove to grow in, thereby creating a larger flame front for a complete combustion. 

On a conventional plug, the flat electrode design crushes the spark, and the overall volume of the flash front is smaller. The conventional method to improve firing was to increase the spark gap. This has a negative effect on the spark. With a U-Groove firing can be greatly improved without increasing the spark gap. 

To help improve ignitability DENSO minimized the portion of the ground electrode that comes in contact with the flame nucleus. Because the area of the ground electrode where the tapered cut comes into contact with the flame nucleus is small, the heat lost to the electrode is lessened and firing performance improves dramatically. The surface area and weight of the ground electrode tip is reduced along with the load in terms of heat and vibrations. This means the spark plug can cope with heavier driving conditions. 

DENSO's patented technology makes Iridium Power one of the best spark plugs you can buy today.