Denso Iridium Race plugs are a set of four iridium spark plugs aimed at high-output direct-injected GM four-cylinders, mainly the LNF, LHU and LTG engines built past 500 whp. The 0.4mm iridium center electrode and tapered U-Groove ground electrode cut the voltage needed to fire and hold up to combustion temperatures above 4000°F. The heat range is 24, equivalent to an NGK 8, so they sit on the cold side for boosted engines. Against standard iridium plugs they trade everyday longevity for spark energy and knock margin, which is why tuners reach for them on big-power builds.
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Rated 4.9 out of 5 from 59 ratings, buyers are overwhelmingly positive. Owners of high-power LNF and LTG cars report clean running and strong ignition under boost.
These Denso Iridium Race spark plugs are made for high-horsepower, direct-injected LNF, LHU and LTG engines (500+ whp). They are sold as a set of 4.
The electrodes deliver maximum spark energy and withstand temperatures above 4000°F. The design lowers the ignition voltage required and improves ignitability, which improves acceleration compared with normal plugs. The plugs are assembled with a 360-degree laser welding process.
A gap of .028" is generally recommended, depending on overall power level. The tip is fragile, so use a proper gapping tool. OEM torque spec is 15 ft/lbs. Do not tighten spark plugs on a hot engine.
