Upgrade your ignition system with the HKS M40HL Super Fire Racing Spark Plug. Engineered for high-performance and tuned engines, the M40HL provides the ultimate balance of ignition efficiency, durability, and carbon resistance.
Whether you are running a tuned Toyota 86 / Subaru BRZ or a high-boost Nissan R35 GT-R, these HKS M-Series plugs are designed to handle the increased heat and cylinder pressure that stock plugs simply can't manage.
High Heat Range (NGK #8): Specifically rated as a "colder" plug than most OEM units, making it ideal for preventing pre-ignition and engine knock in turbocharged or high-compression engines.
0.6mm Iridium Alloy Center Electrode: Requires less voltage to jump the gap, resulting in a stronger, more consistent spark and improved throttle response.
Platinum Ground Electrode: Features a square platinum chip to reduce wear and extend the life of the plug under extreme racing conditions.
Anti-Vibration Design: The short-type outer electrode is reinforced to withstand the high-frequency vibrations found in high-RPM performance engines.
Self-Cleaning Thermal Edge: HKS’s unique ceramic insulator design helps discharge carbon deposits, preventing misfires during extended idling or diverse driving cycles.
Part Number: 50003-M40HL
Plug Type: HL Type (Long Reach)
Heat Range: NGK #8 Equivalent
Thread Size: $12\\text{mm} \\times 26.5\\text{mm}$
Wrench Size: $14\\text{mm}$
Electrode: Iridium Center / Platinum Ground
The HKS M40HL is a popular upgrade for modern high-performance Japanese engines, including:
Nissan: GT-R R35 (VR38DETT), 370Z (VQ37HR), Skyline V36
Toyota: 86 / GR86 (FA20 / FA24), Yaris GR (G16E-GTS)
Subaru: BRZ (FA20 / FA24), WRX (FA20 Turbo / VAG)
Mazda: MX-5 ND (SkyActiv), Mazda 3/6 (SkyActiv-G)
Note: Spark plugs are sold individually. For a 4-cylinder engine (86/BRZ), please select Quantity: 4. For an R35 GT-R, please select Quantity: 6.
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