HKS 50003-M40X M-Series Super Fire Racing Iridium Spark Plug

The HKS 50003-M40X M-Series Super Fire Racing Spark Plug is a high-performance iridium spark plug engineered for demanding, high-load applications. Sold individually, this plug delivers reliable ignition, exceptional durability, and superior resistance to carbon buildup — making it an ideal upgrade for modified and turbocharged engines.

The M-Series distinguishes itself with a 0.6mm Iridium Alloy Center Electrode paired with a Platinum-tipped Outer Electrode, a combination that provides consistent spark energy and a longer service life versus standard copper or nickel plugs. The short-type outer electrode design reduces susceptibility to vibration, while the innovative Thermal Edge and Spark Support Gap geometry optimize flame kernel growth for more complete combustion.

Iridium alloy is selected for its extreme durability — with a melting point of approximately 2,454°C (4,449°F), far exceeding that of platinum at 1,769°C — allowing the fine-wire electrode to withstand high compression ratios and transient knock events without degradation. A nickel-plated housing further protects against corrosion and premature wear.

Key Features:

• 0.6mm Iridium Alloy Center Electrode for precise, consistent ignition
• Platinum Chip Outer Electrode for extended durability
• Short-Type Outer Electrode — anti-vibration design for high-RPM stability
• Thermal Edge Technology for optimized heat dissipation
• Spark Support Gap geometry promotes efficient flame kernel development
• Nickel-Coated Housing resists corrosion and premature deterioration
• Iridium alloy melting point of 2,454°C ensures longevity under extreme conditions
• Designed for high-load, high-boost, and modified engine applications
• Sold individually

The HKS M-Series Super Fire Racing plug is the recommended choice when prioritizing reliable ignition performance, long-term durability, and anti-carbon resilience under sustained high-load driving conditions.