NGK Iridium IX LFR7AIX Spark Plugs (Set of 16) (2009+ 5.7L VVT, 2015+ 6.2L HEMI) - 2309

Product Code: 2309
(1 review) Write a Review
MSRP: $159.95
Usually Ships in 24 Hours
High Horse Performance is Veteran Owned & Operated

These NGK Iridium IX spark plugs feature an ultra-fine center electrode that's designed just thick enough to ensure the maximum durability and life of the spark plugs, and just thin enough to create an accurate and consistent spark. They represent the ultimate evolution of spark plug technology and performance. Iridium is significantly stronger than any metal used in spark plugs today. It's the hardest metal used (in fact, iridium is 6 times harder than platinum), which has allowed NGK engineers to reduce the voltage requirement for a spark.


  • Shorty Spark Plug: No
  • Resistor: Yes
  • Manufacturer Heat Range: 7
  • Electrode Core Material: Copper
  • Electrode Tip Material: Iridium
  • Insulator Type: Projected
  • Spark Plug Thread Size: 14mm
  • Spark Plug Reach: 1.043 in.
  • Spark Plug Seat Style: Gasket
  • Wrench Diameter: 5/8 in. 
  • NGK Part Number: LFR7AIX

Recommended Gap Size vs Boost with factory HEMI coilpacks:

  • 0.029" for stock boost level
  • 0.027" for 15psi
  • 0.024" for 18 psi
  • 0.022" for 20psi
  • 0.020" for 22psi
  • 0.018" for 24psi

 NOTE: Use of nitrous with boost may require smaller plug gaps.

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  • 5
    These Plugs Be Sparkin!

    Posted by Robert Ellsworth on Dec 14th 2023

    Local parts stores don't all carry these, and those that do only have a handful in stock at any given time. Well, the price at HHP can't be beat and they had 'em on my doorstep before the parts store would have had them for me, so you do the math!