NGK R5673-8 Standard Tip Racing Spark Plug

The NGK R5673-8 Standard Tip Racing Spark Plug is a high-performance racing plug engineered to deliver dependable ignition and durability under the most demanding engine conditions. Designed specifically for motorsports and performance applications, it features NGK's Racing Series construction, including a specialized insulator nose configuration that helps improve throttle response and combustion efficiency. Its standard-tip, non-projected design makes it well-suited for engines requiring precise spark placement and reliable operation at high RPM.

Built with a pure alumina silicate ceramic insulator, the R5673-8 offers exceptional strength, heat dissipation, and electrical insulation. A copper-core center electrode helps remove excess heat from the firing tip, while corrugated insulator ribs reduce the risk of flashover during intense operating conditions. Triple sealing technology helps prevent combustion gas leakage, ensuring consistent performance and long-term reliability. The plug also incorporates a V-cut nickel center electrode, nickel ground electrode, solid terminal, and factory-set 0.020-inch (0.5mm) gap.

Featuring a 14mm thread diameter, tapered seat, 11.6mm reach, and heat range 8 rating, the NGK R5673-8 is designed for high-output engines that demand a colder spark plug capable of maintaining stable ignition under heavy loads. With an expected service life of up to 30,000 miles, it combines racing-focused performance with proven NGK durability.

• Solid Terminal
• 0.5mm Gap
• Sold as Each

Shell

• Thread Diameter - 14mm
• Thread Pitch - 1.25mm
• Seat Type - Tapered
• Reach - 11.6mm (.460")
• Hex Size - 5/8" (16mm)
• Terminal Type - Solid
• Overall Height - ISO
• Gap - .020" (0.5mm)

Center Electrode

• Material - Nickel
• Type - V-Cut
• Size - 2.5mm
• Projection - Non-Projected

Ground Electrode

• Material - Nickel
• Type - Standard
• Quantity - 1
• Specifications
• Resistor - No
• Resistor Value - 1K Ohm
• Heat Range - 8

Torque Specs

• Cast Iron: 10.8-18 lb. ft./ Aluminum: 7.2-14.5 lb. ft.
• Longevity - 30k Miles