HKS 50003-M35i Super Fire Racing M35i Iridium Spark Plug ISO Type HR7 14mm

Vehicle Fitment

• Universal Fit - Compatible with any vehicle requiring a 14mm x 19mm ISO-type spark plug with Heat Range 7 (NGK equivalent)

Fitment Notes

• This is a universal spark plug sold individually - verify your engine requires a 14mm x 19mm ISO thread before ordering
• Heat Range 7 (NGK equivalent) is suited for mildly to moderately tuned engines; step up to M40i or M45i for higher boost applications
• Not compatible with engines requiring JIS-type or long-reach (26.5mm) thread plugs - see 50003-M35iL for long-reach applications

Features

• 0.6mm Iridium Alloy Center Electrode reduces voltage requirement while improving ignition performance and long-term durability
• Outer electrode features a square platinum chip for enhanced spark efficiency and reduced electrode wear
• Short-type outer electrode design minimizes weight and resists vibration for stable ignition under high-RPM conditions
• Thermal Edge technology prevents overheating and maintains consistent plug performance across varying load conditions
• Anti-carbon build-up construction keeps combustion chambers cleaner for extended service intervals
• High iridium melting point of 2,454°C tolerates elevated compression and minor knock without electrode deterioration
• Nickel-coated housing prevents premature corrosion and extends overall plug life
• ISO-type thread standard meets international compatibility specifications

Specifications

• Part Number: 50003-M35i
• Series: Super Fire Racing M-Series
• Type: ISO
• Heat Range: 35 (HKS) / NGK #7 equivalent
• Center Electrode: 0.6mm Iridium Alloy
• Outer Electrode: Platinum Chip
• Thread Size: 14mm x 19mm
• Wrench Size: 16mm
• Sold: Individually (per piece)

Included Components

• 1x HKS Super Fire Racing M35i Iridium Spark Plug (ISO Type)

Product Description

The HKS Super Fire Racing M35i (50003-M35i) is a premium iridium spark plug engineered for performance-oriented engines running mild to moderate tune levels. Combining a 0.6mm iridium alloy center electrode with a platinum-tipped outer electrode, it delivers sharper spark initiation, reduced misfires, and improved throttle response compared to standard OEM plugs. The shortened outer electrode design further reduces vibration sensitivity, making it a reliable choice for both street and light track use.

With a heat range equivalent to NGK #7, the M35i is ideal for naturally aspirated performance builds and lightly boosted applications. Its anti-carbon construction and high-temperature iridium composition ensure durability under sustained load, while the nickel-coated housing guards against corrosion. Order the quantity needed to match your engine's cylinder count, as plugs are sold individually.