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Improve acceleration and engine power with IRIDIUM RACING

It’s the age of iridium electrodes. Discover more acceleration with 0.4 mm DENSO Racing Plugs. DENSO would like you to try the 0.4 mm IRIDIUM RACING advantage.
Use IRIDIUM RACING and experience a ride like never before.


Specifications Include Termina

Included with the plug comes with a terminal nut compatible to the Nology Hot Wire and most plug cords around the world. Please remove for vehicle types that do not require terminals. (Some plugs have solid terminals. Please refer to the list.)

Built-in, Highly Reliable Resister

All IRIDIUM RACING plugs specify a resistor, and contain a highly reliable monolithic-type resistor that blocks noise that may affect electronic devices. (IW06 has no resistor.)

Highly Corrosion Resistant, Burnished Nickel Plating

Burnished nickel plating on the housing, a high level of corrosion resistance has been realized. Also, because the amount on the threads is low, the damage to the female thread in the cylinder is reduced.

0.4 mm Diameter Ultra-Fine Iridium Center Electrode

The center electrode tip is able to be made fine using a new iridium alloy with a high melting point. The required voltage is reduced, and ignitability is improved greatly.

All-platinum Ground Electrode

Compared to the nickel alloy used in conventional spark plugs, the high melting point of platinum will reduce such problems as ground electrode melting and wear. Also, the 0.8mm platinum alloy is welded on and gapped without any bending, reducing residual stress and increasing durability.

Insulators for Racing

By using a new, strengthened insulator which was developed during numerous and repeated testing during racing trials, strength is improved by 20%.

Spark Cleaning Pocket

Between the center electrode and the insulator, a small pocket has been opened around the tip clearance. When there is carbon fouling or deposition, this part will discharge and burn off the carbon, restoring electrical resistance. This technology is patented by DENSO (Japan Patent No. 2727558).

Silicone Oil Coating

During the start of the race, non-starting from carbon fouling and carbon deposits can be fatal. To stop this, the insulator has been coated with a silicone coating. Using the water repellency of silicone, the insulator surface is isolated from moisture and carbon, preventing a decrease in resistance.

360° Laser Welding

The process used to join the iridium tip is a highly reliable “All-around Laser Welding” process that is able to withstand various kinds of driving conditions.

Improved Acceleration

Improved acceleration performance on the circuit.

With an ultra-fine, 0.4 mm diameter center electrode, IRIDIUM RACING plugs are the realization of superb ignition performance and reguired voltage at high levels. Misfires have been controlled and will allow you to have steadily high levels of response and increased acceleration.


Improved Horse Power

More power with an ideal combustion cycle.

Through great ignitability and reguired voltage, non-firing and misfires under a variety of conditions has been greatly reduced. As a result, combustion conditions have improved increasing enginen output.


Actual products may differ from images shown.