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Denso Iridium Race Spark Plugs

This is our secret weapon spark plug for high horsepower direct injected LNF, LHU, and LTG cars (500+whp) where we start to have issues with the electrode burning off.  This has a different style tip which doesn't burn off and cause valve train/piston/block damage like the other plugs can.

Iridium Power® plugs are for drivers that care about performance as well as drivers that care about mileage. These plugs best demonstrate their performance improvement during acceleration. The world's smallest center electrode (0.4mm) and specially shaped ground electrode delivers maximum spark energy while withstanding temperatures greater than 4000º F. These features combine to achieve higher ignitability and require lower spark voltage than ever before. As a result, acceleration improves in comparison with normal plugs.


  • Tapered cut, U-Groove ground electrode
  • 0.4mm iridium center electrode
  • 360-degree laser welding assembly process
  • Required ignition voltage reduced
  • Unsurpassed center electrode durability

These work in LNF, LHU, & LTG

Comes in a set of 4.

Customer Reviews
4.8 Based on 18 Reviews
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Bradford B.
United States United States
Great plugs for LTG

Shipped very fast, these are hard to get sometimes so I'm glad ZZP keeps a stock of them. These seem to have a better idle and run smoother than the stock plugs with a tune.

Juan J.
United States United States
Best plugs for your money

After talking to Beckey with her recommendation and please listen to anything they have to say because they know they stuff received them and they were personally gapped by beckey to recommended by zzp pulled the old ones installed took it out for a run and noticed a completely different car so yes best money for your investment ….. thanks to the whole team at zzp and keep doing what y’all are doing very very happy

Harvey C.
United States United States

Hi , have received the plugs, but seems that I have to replace the engine pistons!

Derick F.
United States United States
Hard to find anywhere else!

Hard to find anywhere else! These are perfect for Full Bolt on E85 ATS. Engine runs very smooth after adding with proper gapping. ZZP was great answering my questions and providing the proper gapping based on my mods!

Randy M.
United States United States
A must upgrade

So far so good no complaints