Iridium Spark plugs | FerrariChat

Iridium Spark plugs

Discussion in 'Technical Q&A' started by Marty, Nov 21, 2003.

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  1. Marty

    Marty Karting

    Nov 21, 2003
    Boston/PTown/SW FL
    Full Name:
    Martin Stark
    Has anyone tried a set of NGK or Denso iridium plugs? I'd like to change the oem Champions (which are now "unobtainium") before I do some more dyno tuning on the tr. I like the concept of the very thin (.4mm) center electrode in the Denso's.

    If anyone's interested here's a link to a couple of the baseline runs I made several years ago:
  2. enzomoon

    enzomoon Guest

    A close friend of mine in Atlanta installed NGK iridium plugs on his 512TR two weeks ago. I only had a brief ride after the switch from oem but I did notice that the car idled more smoothly and was, interestingly, quieter than before. He said that he felt the throttle response was improved but again those were early observations based on a brief ride. If you would like his email let me know.


  3. atlantaman

    atlantaman Formula 3

    Mar 31, 2002
    Roswell, Georgia
    Full Name:
    you need to consider that the irridium plugs are resistor plugs--therefore---if you are using red plug extensions--go get some black ones to get the irridium plugs to opperate correctly.
  4. jselevan

    jselevan Formula 3

    Nov 2, 2003
  5. Hubert

    Hubert F1 Rookie

    Jan 3, 2002
    The Left Coast
    no need.
    dyno proves not increase in power of iridum/pt plugs v. copper plugs (of the same temp range).
    using the pt/iridium plugs is a matter of convinence and service life. they last longer,and therefore are more convinent, the nominal increase in power that you may experience could be negated by a change in ambient conditions; it's that small, in the real world.
    in high compression applications, etc ( where the temps are higher) you should give the temp range of the plug more consideration , and the non-reactive materials may give you better protection in a higher temp environment (but you shouldn't be running hot anyway, if you've got your air/fuel ratio setup right -- otherwise you'll be rebuilding the motor b/c of detonation).
    if your plugs are a pain in the ass to change frequently, then i can understand using the "exotic" plugs , but the hp advantage is marketing hype.
  6. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    Charles (atlantaman), not necessarily. I have the stock red (oem) plug extenders on my 328, and when measured, they have no not all red extenders have resistors in them. There was a thread on this in the old Chat website...

  7. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    Iridium can initiate a spark easier because the electrode can be made smaller in diameter. This creats a larger electric field gradient, which is easier for a spark to jump.

    Iridium can get away with a small diameter tip because it is so resistant to heat, acids, and other things that happen in the combustion chamber. A smaller tip heats up faster (starting), but does not initiate detonation because it is so small, and with its high specific heat does not 'feel' hot to the compressin mixture in the cyclinder chamber.

    Note: you can put in 7 sets of NGK copper plugs for the cost of a single set of Iridiums (if you do your own work, and don't count the towing bill) So if you idea is 30K miles on one set of plugs, then Iridium is a decent choice. On the other hand, if you are changing plugs each year during winter maintanence, regular copper plugs are just fine.
  8. Marty

    Marty Karting

    Nov 21, 2003
    Boston/PTown/SW FL
    Full Name:
    Martin Stark
    Denso's argument is that their "U" shaped electrode design doesn't shroud the spark as much as a standard electrode plug. The oem A6G Champion plug does have reduced diameter center electrode and a smaller ground electrode. I believe that reduced electrodes promote easier firing across a wider range of conditions. The more erosion resistant metals allow the use of reduced size electrodes while providing acceptable service life.
  9. AJS328

    AJS328 F1 Veteran

    Apr 23, 2003
    New Jersey
    Full Name:
    Augustine Staino
    I replaced the Champions with NGK Iridium plugs a few weeks back and my car has been fine since. I was having a problem with the extenders burning through before that so I just replaced everything. So far so good.

    I am curious about the red extender vs. black extender comment. Do the different extenders really make a difference with Iridium plugs. My car has driven fine but if there is an advantage to having a different extender for these new plugs, I'd like to know. Thanks.
  10. 348 Turbo

    348 Turbo Formula 3

    Jul 17, 2002
    I replaced the champion plugs in my 348 Trubo with Denso Iridium plugs and solid silver core racing wires, no extenders. I was trying to cure a high boost miss. No difference at all. The Champion plugs Norwood had installed proved to give identical service with the factory wires in my case. FWIW......................
  11. Tifosi1

    Tifosi1 Formula 3

    Feb 17, 2002
    Pearl River, LA
    Full Name:
    Kelly J. Vince
    I've put them in my Ford F150. over $100.00 bucks. I like them and will put them in the Ferrari . I got some NGK platinum pugs in there now. When I start noticing a miss or 20,00 miles I will try the IR's.


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