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Is there a difference with Iridium Spark Plugs

This is a discussion on Is there a difference with Iridium Spark Plugs within the External Engine forums, part of the LSx Technical Help Section category; I thought this might be a good discussion. I haven't been on the web for very long but I would ...

  1. #1
    Join Date
    Jun 2008

    01 TA

    Is there a difference with Iridium Spark Plugs

    I thought this might be a good discussion. I haven't been on the web for very long but I would like to get some feedback from you guys if possible.

    My own experiences have shown me noticeable seat of the pants difference going from a TR55(copper) to a TR55IX(iridium) and again to a K6CF(performance iridium) spark plug.

    I suppose I can share what knowledge I have on the subject and what I have experienced.

    I suppose the biggest factor I went to Iridium in the first place was because of how brutal it is to get to the rear spark plugs. I just don't want to be replacing them often.

    Initially I bought the TR55's and noticed more of an idle "miss" in the exhaust note. Didn't make a huge difference in part throttle going from the stockers to the TR55's but it just didn't seem to be as snappy with the throttle. After about 6K I figured it was time to do the deed again and not wanting to replace plugs all the time I bought the NGK TR55IX Iridiums.

    Part throttle response was noticeably crisper, for lack of a better word, and power delivery seemed better. I then did a cam, intake, head swap. The TR55IX's had about 4K on them so they stayed in until I thought it would be smart to get a slightly colder spark plug.

    The crispness and response increased allot after upgrading to the WeaponX K6CF performance Iridium spark plugs. Jumping into the WeaponX K6CF, I just didn't expect any change but noticed improved throttle crispness. I mean it is just really snappy and quick to respond to pedal movement over the TR55IX plugs, no other changes were made.

    What are your guys feelings on the subject? In doing some research the K6CF plugs have about 5000-10,000 ohms less resistance, have the extended life I need and I noticed a difference. It is a non issue about the reduced resistance, it obviously makes a difference but I am interested in the part throttle and "miss" I noticed at idle with the NGKs. Also, I'm sold on the iridium theories now after reading some information. Particularly this from wikipedia.

    "The center electrode is usually the one designed to eject the electrons (the cathode) because it is the hottest (normally) part of the plug; it is easier to emit electrons from a hot surface, because of the same physical laws that increase emissions of vapor from hot surfaces (see Thermionic emission). In addition, electrons are emitted where the electrical field strength is greatest; this is from wherever the radius of curvature of the surface is smallest, i.e. from a sharp point or edge rather than a flat surface (see Corona discharge). It would be easiest to pull electrons from a pointed electrode but a pointed electrode would erode after only a few seconds. Instead, the electrons emit from the sharp edges of the end of the electrode; as these edges erode, the spark becomes weaker and less reliable.
    The development of precious metal high temperature electrodes (using metals such as yttrium, iridium, platinum, tungsten, or palladium, as well as the relatively prosaic silver or gold) allows the use of a smaller center wire, which has sharper edges but will not melt or corrode away. The smaller electrode also absorbs less heat from the spark and initial flame energy. At one point, Firestone marketed plugs with polonium in the tip, under the questionable theory that the radioactivity would ionize the air in the gap, easing spark formation."

    This seems all valid after some research. The copper plugs have a larger surface area, and copper erodes it's sharp edges fast. While I was once sold on the fact that copper is a better conductor the problem is, which I'm finding, that electricity doesn't conduct through the spark gap, it archs through the spark gap and starting the arch is the most important thing.

    For example. Lightning discharges when the surface area of the cloud is small and has a large built up charge. The same seems to apply here. A cloud(water vapor) is hardly a good conductor but the principals of electric charge, in a small condensed area for the energy, creates a lightning strike. The reason I bring this up is because a smaller anode has a higher electrical potential and it is easier to discharge energy from a small sharp point rather then a large copper face. It just makes sense.

    To put it in perspective. If I have a cloud that can discharge the energy as a lightning strike and the area of the cloud is suddenly increased, it will no longer discharge because the electrical potential has reduced since the surface area has increased. I could say the same thing about the spark plug faces. It would be easier to discharge from a smaller point then a larger point.

    Anyway, let me know what you guys think.

  2. #2
    Slow'er'Ass Mr. Luos's Avatar
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    Personally...I don't think so. Just how long they last.

    Should be a good discussion though.
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