Whatever your use or engine set-up, the correct choice of spark plug is very important. Iridium is very heavy and dense metal, ensuring that NGK spark plugs have a longer lifespan than OEM ones, withstanding more than 100.000 km in standard use. These plugs have heat range 8. This plug is great for fully modified 2JZ turbo engines running over 500hp. The ultimate evolution of a performance spark plug. The natural properties of Iridium offered NGK the opportunity to create one of the world's finest spark plugs. The result are spark plugs that require less voltage to spark, burns fuel more efficiently, sparks at leaner air/fuel mixtures, and delivers higher horsepower and better gas mileage.
If the letters (for example BKR-EIX) indicate the spark plug's shape and thread size, the numbers (from 6 to 9) indicate the heat range, basically meaning how well the spark plug can operate in intense conditions. The higher the number, the more the spark plug will be "cold", and more adapted to tuned engines and sporty use. A cold spark plug is designed to operate at higher than average temperatures and disperse the heat inside the cylinders, improving combustion, performances and engine reliability, reducing the risk of detonation.
NOTE: make sure you only fit cold spark plugs if your car requires them, otherwise you could encounter problems such as difficult cold starts and rough idling.