Denso 5316 Spark Plug

Denso Iridium Power Spark Plug 5316

Denso Iridium Power spark plug 5316 is built for precise ignition performance in classic Porsche 911 and select Maserati applications. It uses a 0.4 mm iridium center electrode to promote strong spark concentration, along with a tapercut and U-groove ground electrode design for efficient flame initiation.

Key Features

• Iridium center electrode tip material for stable ignition performance
• World’s smallest 0.4 mm iridium center electrode design
• Tapercut, U-groove ground electrode tip design
• 5000 ohm resistance for ignition system compatibility
• Flat seat, 14.00 mm thread diameter, 19.00 mm reach
• Pre-gapped to 0.7 mm
• Nickel ground electrode core with copper center electrode core
• Manufacturer heat range 24
• Cross-reference: DENSO Auto Parts IW24
• Cross-reference: Porsche 999 170 128 90

Product Details

This Denso Iridium Power spark plug is part of the Iridium Power line, a product family focused on fine-wire iridium electrode construction for responsive ignition characteristics. In Porsche 911 and Maserati 425, Spyder, and Biturbo applications, part number 5316 provides the electrode geometry and heat range needed for proper secondary ignition service. The compact iridium tip and tapered ground design support consistent spark delivery in engines that require a flat-seat plug with a 20.6 mm hex.

Vehicle Fitment

• Fits 1981-1989 Porsche 911, N/A
• Fits 1974-1977 Porsche 911, N/A
• Fits 1969-1971 Porsche 911, N/A
• Fits 1965-1967 Porsche 911, N/A
• Fits 1986-1987 Maserati 425, N/A
• Fits 1986-1987 Maserati Spyder, N/A
• Fits 1984 Maserati Biturbo, N/A

Common Replacement Reasons

• Misfire or rough idle from worn spark plug electrodes
• Hard starting caused by weakened ignition spark
• Reduced throttle response from degraded plug performance
• Service replacement for aging Porsche 911 ignition components
• Replacement for Maserati 425, Spyder, or Biturbo tune-up service

Installation Notes and Quality Assurance

Verify thread diameter, reach, seat type, and heat range before installation. Confirm the gap specification against the engine’s service requirements and inspect ignition components for wear before final assembly. Denso manufactures the Iridium Power line with fine-wire iridium electrode construction for consistent ignition service in the listed applications.