NGK R5671A8 4554 V Power Racing Turbo Nitrous Supercharged Spark Plugs Set of 8 - Shell - Thread Size: 14mm - Thread Pitch: 1.25mm - Seat Type: Gasket - Resistor: No - Reach: 19mm (3/4") - Hex Size: 5/8" (16mm) - Terminal Type: Solid - Overall Height: ISO - Gap: .031" (0.8mm) Center Electrode - Material: Nickel - Type: V-Cut - Size: 2.5mm - Projection: Non-Projected Ground Electrode - Material: Nickel - Type: Standard - Torque Specs: Cast Iron: 18-25.3 lb. ft. Aluminum: 18-21.6 lb. ft. - Brand: NGK - Heat Range: 8. 4554 / R5671A8 - NGK Racing Series plugs are engineered to withstand the harshest engine conditions. Special insulator nose configurations improve throttle response. Corrugated ribs prevent flashover. Pure alumina silicate ceramic insulator, provides superior strength and better heat transfer. Copper core aids in heat removal. Triple seals prevent leakage.