HKS 50003-MR45HLZ Super Fire Racing MR-Series Ruthenium Spark Plug HLZ HR 45

Vehicle Fitment

• Universal Fit - Multiple Applications (MR-HLZ Type, Protrusion Type, 12mm x 26.5mm Thread, 14mm Hex)

Fitment Notes

• Universal part - no vehicle-specific fitment assignment applies
• Protrusion type (shell-protruding electrode) design - electrode tip extends approximately 2mm further into the combustion chamber than a standard plug; this shape is required by certain direct-injection turbo engines and must match the OEM plug profile exactly before installation
• Installing a protrusion-type plug in an engine not designed for it may cause serious engine damage - always verify shape compatibility against the installed plug before ordering
• HKS adopts a shell protrusion design (vs. bracket protrusion on some OEM plugs) to improve pre-ignition resistance and structural strength
• Sold individually (1x per listing) - order quantity to match your engine's cylinder count

Features

• Ruthenium alloy center electrode delivers higher abrasion resistance and ignition reliability than iridium, with extended service life under high-load and boosted conditions
• Ruthenium electrode enables more complete fuel combustion, resulting in sharper throttle response, smoother idle, and improved cold starts
• Protrusion-type electrode positions the ignition point deeper into the combustion chamber for a wider, more efficient flame spread
• Square platinum chip on outer electrode improves combustion speed, ignition quality, and long-term wear resistance
• Short-type anti-vibration outer electrode reduces weight and resists mechanical stress during aggressive driving
• Brass terminal provides a secure, film-fit connection to plug wire or coil-pack
• Plating-coated housing delivers improved insulation performance and corrosion resistance
• Thermal edge and spark support gap actively reduce carbon fouling on tuned and direct-injection engines

Specifications

• Part Number: 50003-MR45HLZ
• Series: Super Fire Racing MR-Series
• Type: MR-HLZ (Protrusion Type)
• Center Electrode: Ruthenium Alloy
• Outer Electrode: Square Platinum Chip
• Terminal: Brass
• Thread Size: 12mm x 26.5mm (Protrusion Type)
• Wrench Size: 14mm
• Heat Range (HKS): 45
• Heat Range Equivalent (NGK): #9
• Heat Range Equivalent (Denso): 27

Included Components

• 1x HKS Super Fire Racing MR45HLZ Spark Plug

Product Description

The HKS Super Fire Racing MR45HLZ belongs to the MR-Series - a next-generation lineup that builds on the proven M-Series platform by replacing the iridium center electrode with a ruthenium alloy tip. Ruthenium offers greater abrasion resistance and durability than iridium, supporting more consistent ignition performance over a longer service life, particularly in direct-injection turbocharged engines that run increased boost or light tuning. The result is a more complete fuel burn, noticeably sharper throttle response, smoother idle, and better cold-start behavior compared to standard precious-metal plugs.

What sets the MR45HLZ apart from other M-Series variants is its protrusion-type electrode design - the plug tip extends approximately 2mm further into the combustion chamber than a standard plug, placing the spark closer to the fuel mixture for a wider and more efficient flame spread. This protrusion format is required by specific direct-injection engines such as those found in the Honda Civic Type R (FK8/FL5) and Suzuki Swift Sport (ZC33S). Always compare the shape of the new plug against the installed OEM plug before fitting - using a protrusion-type plug in an incompatible engine can cause serious engine damage. Sold individually.