As technology advances, the efficiency of the spark plug has increased, resulting in higher combustion efficiencies. The design evolution has reduced the quenching effect on the flame kernel. The quenching effect is the heat absorption by the spark plug ground electrode and center electrode, which hinders the flame kernel efficiency. The NGK spark plug has seen many changes to its design over the last 75 years, with most occurring in the last 30 years.
NGK introduced the V-Power® spark plug in the 1970s and is named for their specially designed V-groove center electrode. This groove in the center electrode focuses the spark to occur between the outside edges of the center electrode and the ground electrode for improve ignitability and better flame expansion. This design relocated the flame kernel to the outside edge of the spark plug, which reduced the quenching effect. The V-Power spark plug was adopted by many OE manufacturers and is still very popular today.
With the introduction of precious metals, first Platinum in the 1980s and Iridium in the 1990s, the spark plug center electrode has reduced in size. Both Platinum and Iridium are extremely dense materials with high melting points, making them ideal for center electrode construction. When used at the tip of the center electrode of the spark plug, Iridium is a denser metal alloy, six times denser than Platinum. This provides increased service life, improved ignitability and better throttle response. Where a traditional nickel-alloy spark plug had a center electrode diameter of 2.5mm, the newer precious metal spark plugs have a center electrode diameter of less than 1.0mm. This smaller diameter center electrode provides more area for flame kernel expansion, further reducing the quenching effect. In 2000, NGK introduced the IRIDIUM IX® spark plug, which has a taper-cut ground electrode. This taper-cut shape provides even more area for flame expansion, further reducing the quenching effect. Available in colder heat ranges, NGK Iridium IX® is perfect for modified and high-performance engines.
Recently, as emissions and fuel economy requirements have been made tougher to meet by automotive manufacturers, increased use of turbo charging and gasoline direct injection has become common on modern engines. To further increase spark plug ignitibility, new tip designs such as Dual Fine Electrode (DFE) spark plugs have been introduced. DFE spark plugs feature opposed fine-wire electrodes from both the center electrode and ground electrode to maximize ignitibility under these extreme conditions while reducing quenching. NGK has collaborated with OEMs to make its precious metal spark plugs part of their original equipment. LASER IRIDIUM® spark plugs are actually custom built for each vehicle manufacturer for the needs of the individual engine platform.
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