HKS Super Fire Racing Spark Plug - M40iL (50003-M40iL)

Maximize your engine's reliability and power with the HKS M40iL Super Fire Racing Spark Plug. This high-performance Long Reach ISO Type plug is the definitive upgrade for modern JDM performance engines, including the Mitsubishi Evolution IX and high-boost Subaru WRX/STI builds.

With a heat range equivalent to NGK #8, the M40iL is a "colder" plug designed to handle the extreme cylinder temperatures of remapped, turbocharged, and track-driven vehicles, effectively preventing pre-ignition and engine knock.

Why Choose the HKS M40iL?

• Ruthenium & Iridium Technology: Features a 0.6mm center electrode that reduces voltage requirements for a stronger, more consistent spark and improved durability.

• ISO Long Reach Design: Specifically engineered for cylinder heads that require a $26.5\\text{mm}$ reach, ensuring the spark is perfectly positioned in the combustion chamber.

• Platinum Ground Electrode: A square platinum chip improves ignition quality and extends the service life of the plug under high-load conditions.

• Anti-Vibration Short Tip: The outer electrode is shortened and reinforced to withstand the high-frequency vibrations of high-RPM performance engines.

• Thermal Edge & Spark Support: Features HKS’s signature ceramic insulator design that help discharge carbon buildup, preventing misfires during idling or cold starts.

Technical Specifications

Vehicle Compatibility

The HKS M40iL is a popular performance upgrade for:

• Mitsubishi: Lancer Evolution IX (4G63 MIVEC)

• Subaru: WRX & STI (EJ20/EJ25 Long Reach heads), Liberty GT, Forester XT

• Nissan: 350Z (VQ35DE - select models), Altima, Maxima

• BMW: Select M54 and early N-series engines (Check reach requirements)

• Honda: Civic Hybrid & Insight (Select models)

Purchasing Note: Spark plugs are sold individually in Australia. For a Mitsubishi Evolution IX, please order Quantity: 4. For a Subaru STI or Liberty GT, please order Quantity: 4.