NGK Spark Plug Stock # 3691

The NGK Spark Plug Stock # 3691 (TR8IX) is a premium iridium spark plug designed for reliable engine ignition across a variety of automotive applications. It is ideal for drivers and mechanics who seek consistent cold-start performance and extended service intervals. This spark plug effectively replaces worn electrodes that can hinder combustion efficiency and fuel economy.

Constructed with iridium, the TR8IX offers superior durability compared to standard copper or platinum plugs. Its smaller, more precise firing tip creates a focused spark kernel, promoting faster flame propagation. The tapered seat design ensures proper sealing in the cylinder head, preventing leakage and maintaining combustion chamber integrity.

Mechanics and automotive enthusiasts trust NGK plugs for both OEM replacements and performance upgrades. The TR8IX is particularly beneficial for fuel-injected, turbocharged, and high-compression engine builds, where electrode consistency is crucial for ignition timing precision. With a service life typically ranging from 25,000 to 100,000 miles, it meets the demands of modern engines.