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Iridum plugs for regular plug money

Discussion in 'Technical Q&A' started by jeffdavison, Oct 18, 2004.

  1. jeffdavison

    jeffdavison F1 Rookie
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    Jul 29, 2002
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    Jeffrey Davison
    Looking for new plugs for my F355, I came across a new plug from NGK.

    Available Plugs for the 355 were either regular plugs, NGK Laser Cut Platinum or Denso Iridiums. Regular plugs were about $7, NGK Lasers (PMR7A) were $12, and the Densos were $14 (IU22). Not to crazy about the Split-Fires so I won't mention them again.

    The new NGK Iridiums equivalents (CR7EIX) came in at $6.50 each! I read in another forum that it is a marketing decission to price them less than their Platinum plugs.

    The difference only comes to about $50 or so and that won't stretch the budget of most owners here not to use them, but just wanted to pass the info along. A few bucks here, a few bucks there it begins to add up. I guess it's my Fiat roots.

    Get them before NGK gets greedy!

    JD
     
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  3. pflowers

    pflowers Karting

    Oct 31, 2003
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    Paul Flowers
    The only problem is that the Iridium plugs do not come with the screw on ends that are necessary to fit the Ferrari plug wire caps. They will probably work fine if you can get the ends. The PMR7A plugs do not have screw off caps so you can not use the caps from the old ones.
     
  4. jeffdavison

    jeffdavison F1 Rookie
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    Yep, easily obtainable and cheap!. MUCH less that a even a small pecentage of the cost difference of the plugs. Worth the effort, if you're not too lazy to spend a few keystrokes seaching the net. Also good reason to strip them off any older plugs you've changed on other cars (if you do your own plugs).

    I have a drawer full of old plugs that I've changed as a matter of course over the years (many really didn't need changing but it's a yearly ritual for me).

    I'm converting to coil-on-plug and the sold terminal won't work with the Denso coils, so the 4 mm terminal thread is a good thing as it gives one "options".

    JD
     
  5. TOM B

    TOM B Formula 3

    Jul 24, 2003
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    Thomas Buckley
    I've been using NGK Platinum D7EVX plugs for the last few years in my 3.2 Mondial. They have been discontinued by NGK and replaced by the Iridium plugs. I was also please with their price being $4.00 less than the platinums. NGK doesn't make a "7" heat range plug in Iridium so I got the DR8EIX plugs. It turns out the "8" heat range is what NGK recommends for the 3.2 engine. They've been in for a month now and seem fine.

    Better AND cheaper? How un-capitalistic can you get!? ;)
     
  6. Ken

    Ken F1 World Champ

    Oct 19, 2001
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    Kenneth
    Why are the Iridums better? The only plug feature I'm concerened with is fouling. I've had best luck with Autolite in my Lotus; Bosch were good but I like the Autolite's better for my particular car. Would NGK's be any better?

    Ken
     
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  8. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Jan 11, 2001
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    Preventing fouling is the main benefit of the exotic small diameter center electrode plugs -- the exotic materials have higher melting temperatures so the electrodes can be made smaller causing them to run at a higher (more self-cleaning) temperature. There's also some mumbo-jumbo given about the higher charge density of a smaller electrode being somehow beneficial for initiating a spark (but I've never seen a real clear explanation). The pecking order is:

    Standard (2.0mm diameter) -- NGK ES series
    Palladium (1.0mm diameter) -- NGK EV series
    Platinum (0.8mm diameter) -- NGK EVX series
    Iridium (0.7mm diameter) -- NGK EIX series
    (but the cheaper Palladiums are no longer available)

    Really made a difference in my high-mileage carbed ex-308 -- took the fouling interval from a few hundred miles with a standard 2 mm diameter plugs to 5~10K miles.

    I wouldn't like paying a dealer $15~$25 each, but for $6~8 each from www.clubplug.net why not try a set in your Lotus (they even show Lotus in their application table;))? The photos show a 2mm diameter standard NGK ES vs the NGK EIX:
     
  9. 512Professore

    512Professore Karting

    Feb 3, 2004
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    Brian Strasburg
    I have installed the NGK Iridium plugs in my 512TR about a year ago, and quite pleased with their performance. The factory specified Champions were only available at the dealer for big $$, and when twelve are needed.... over $300 for spark plugs was not acceptable. So, I was driven to find a better solution, and since the Iridiums are newer and better technology for significantly reduced costs, it was a "no-brainer". I obtained the NGK's from Clubplug.net, located in Canada, and shipping times are a little longer than normal.

    Yes, the NGK Iridiums do not come equipped with the screw on end caps, but a trip to the local "Wally-World" and purchase 12 of the cheapest plugs($.97) that had the screw on end caps fixed that issue.

    Because of the much finer and more highly focused center electrode, you actually get a more defined spark with higher energy, which enabled me to open the gap another .002in. Electricity always likes the path of least resistance, and the sharper the point, it is more likely that the electrical discharge will occur at the center point of the electrode, causing nearly all of the energy to be released in one large burst, instead of bleeding off onto the sides with the older and wider center electrode.

    If you have the time, you can also "index" the plugs, which will focus/aim the spark energy right at the intake valves, which is where you will find the highest density of air/fuel, thereby causing more complete combustion. This is an old trick from the drag racing world.

    Jeff, I must say a good job on the research for F355 spark plug wires and such. This type of research and information is quite valuable, and I would like to see more of this on Fchat. Sourcing these types of parts for cars such as the 512TR(and others) is important, because if you can find a pair/set of wires for the 512TR you are very lucky, and must have a fat wallet as well. We all know the dealership pricing on parts is way out of line. Keep up the good work !!!
     
  10. Frank R. Masiarz

    Nov 10, 2003
    126
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    Frank R. Masiarz
    Hi.............

    Two questions:

    1) What effect does an increase in plug gap of 0.002 inch have on combustion efficiency and/or plug life ??

    2) Do you "index" plugs with changes in washer thickness; if so, must you change the installation torque ??

    Frank............23005
    www.masiarz.net/bb_resource
     
  11. Aeroengineman

    Aeroengineman Formula Junior
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    Oct 5, 2003
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    Dave Tegeler
    Use the factory plugs I just made the mistake of buying the NGK plus and they have the wrong reach and will produce the wrong combustion pattern
     
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  13. f355spider

    f355spider F1 World Champ
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    #10 f355spider, Nov 20, 2006
    Last edited by a moderator: Sep 7, 2017
  14. TommyA

    TommyA Formula Junior
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    Oct 7, 2002
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    Does anybody have any experience with the Bosch 4?
     
  15. f355spider

    f355spider F1 World Champ
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    Tommy, only use NGK.
     
  16. No Doubt

    No Doubt Six Time F1 World Champ
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    #13 No Doubt, Nov 20, 2006
    Last edited by a moderator: Sep 7, 2017

    I haven't found any of the Bosch +4 plugs compatible with my 348, but I used the +4 plugs on my 95 Corvette and 86.5 Porsche 928, the former seeing a four hp increase in back to back dyno runs replacing new Champions with the +4's.

    Frankly, the single grounds of Champions/AC Delco and NGK is/are century-old technology. It's a dated design.

    I've used the Splitfire Triple Platinum V, the AC Delco, and the NGK on my 348 with good results.

    Bosch's newest "Fusion" plat/irid +4 plug has perhaps the best new ground design, though. It's spark is fully exposed to the cylinder's air/fuel mixture...none of the spark is shaded by the center ground electrode of the older designs.
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  17. F355Bob

    F355Bob Formula 3

    Has anybody tired Densco plugs on a F355. One of the Japanese Ferrari website used them but the text was in Japanese so I tell why they were recommending them.
     
  18. gothspeed

    gothspeed F1 World Champ

    May 26, 2006
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    Four horses?? I think I may be needing plugs soon ;)
     
  19. f355spider

    f355spider F1 World Champ
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    If you want Iridium plugs for a 355, looks like Denso makes one that fits:
    http://www.densoiridium.com/find_part.php
    If you check their cross reference, the IU22 even crosses directly to the NGK PMR7A.

    I have not compared the length or tried them yet, so YMMV.
     
  20. markcF355

    markcF355 F1 Rookie
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    Jun 6, 2004
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    I bought a 400i for my daily. Although the Champ plugs looked OK, I changed them to the Denso IW24 Iridiums, just because (I'm crazy). I am amazed at the improvement. I will be putting them in the Spider as well. I never thought a spark plug could make such a difference.

    Also, Jeff and anybody else: I am thinking about changing the 400i over to electronic fuel injection. Can you recommend a controller. Something less than $1k. If it costs more than that I'll make my own. (Crazy, not cheap) Maybe an all in one unit so I can run cops and efi from the same box.
     
  21. Mike C

    Mike C F1 Veteran
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    Aug 3, 2002
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    Mike Charness
    That sounds like very wishful thinking...
     
  22. f355spider

    f355spider F1 World Champ
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    When you get the Denso Iridiums for your 355, please let us know if they are of the correct length (nose protrusion).

    Thanks,
    Dave



     
  23. markcF355

    markcF355 F1 Rookie
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    I was looking around and found a company called Haltech that makes a fuel controller in the sub 1k price range.

    I'm not sure about the model, but their F10X looks like it has promise.

    Also, does anyone know the K&N part number for 400i air filters?
     

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