DENSO makes a spark plug for every personality – from 100,000 miles to 150+ mph!

Welcome back! Let’s continue our look at the world of DENSO’s spark plug innovation. This week: the High Performance Series.


For high performance applications, DENSO offers two spark plugs that are designed to withstand the heat of competition as well as the rigors of daily driving.

Iridium Power® spark plugs deliver that extra burst of power when you need it most. These spark plugs combine the use of Iridium alloy in the electrode and laser welding technology to dramatically increase firing performance, which results in maximum horsepower and torque.

Iridium is six times harder and eight times stronger than platinum, this allows DENSO engineers to shrink the center electrode tip to only 0.4mm, the world’s smallest, and still maintain durability. By reducing the size of the electrode, it reduces the required voltage for the plug to fire, resulting in improved performance. DENSO patented the Iridium alloy formula used in our spark plugs. It has over 90% Iridium and small amounts of Rhodium, which is added to even further reduce oxidation.

In technical terms: Iridium Power® spark plugs are designed to withstand temperatures over 4,000 degrees F while a U-Groove has been cut inside the ground electrode to maintain the lare volume of space required to form the nucleus of a flame. In addition, the tip of the ground electrode has been cut to form a taper. This greatly improves firing performance by reducing “quenching.”


  • 0.4mm Iridium center electrode
  • Tapered U-Groove ground electrode
  • 360-degree laser welding

What’s the difference between Iridium Power and Iridium Long Life?

Iridium Power is a high-performance spark plug. The Iridium Long Life is the genuine part that comes OE from car manufacturers. FYI: Iridium Power spark plugs are direct replacements for OE spark plugs and do not require any special tuning.

From extreme race conditions to the daily driver, Iridium Power spark plugs are the ultimate choice for performance.

Iridium Racing® spark plugs are the elite spark plugs for the serious racer. These spark plugs are designed to deliver more power and torque as well as increased engine efficiency and fewer misfires – features that are critical for race conditions.

The construction of these spark plugs is different than OE-style plugs. For example, they use a strengthened insulator, which was developed during numerous racing trials. It is 20% stronger than previously used insulators for unsurpassed reliability.

In addition, with racing vehicles, starting problems caused by carbon deposits and bridged plugs before the start of a race can be fatal. To prevent this, Iridium Racing spark plugs have a film of silicone oil applied to the insulator. The water-repellent properties of the silicone keep the insulator surface free from moisture and carbon to prevent any losses in plug insulating performance.

Another feature all Iridium Racing plugs contain is a highly reliable monolithic-type resistor that blocks noise that may affect electronic devices.


  • 0.4mm Iridium-Rhodium alloy center electrode
  • 0.8mm 100% pure Platinum ground electrode
  • Patented self-cleaning insulator/electrode
  • 360 degree welding process

DENSO Iridium Racing spark plugs are the premier choice for racing vehicles because they deliver durability under the harshest, hottest conditions, preventative and self-cleaning technology, lower voltage requirements and the highest performance possible. That makes them the winning choice because there is nothing better.

We hope you’re enjoying this dive into DENSO’s spark plugs. We’ll see you next week as we discuss the OE-Type Series….

Find out more about DENSO parts for your car