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Change Of Plugs ?

Discussion in '2013-14 Shelby GT500' started by Jam421, Mar 24, 2020.

  1. Jam421

    Jam421 Jam421 Established Member

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    How often do you guys swap NGK Iridium plugs? I'm running the NGK 7's. The car has been in winter storage. I was planning a plug change but was surprised I only put 2,200 miles on the car going to shows last season.
     
  2. darksykal

    darksykal Member Established Member

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    manual says 45k for stock

    I plan on doing mine (NGK TR7ix) every 10k or so but haven't reached that many miles yet
     
  3. Chancey

    Chancey Auto Affection Established Member

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    I am a bit of an “overkill” guy to say the least. I change mine every 3,000 or so miles. They still look good with minimal wear each time, but there is no better way to determine whats going on in our engines. Especially with a supercharged motor, its cheap insurance for me. Because I drive mine hard and almost daily. If I had a garage queen, I would not inspect them near as often.
     
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  4. CobraKid04

    CobraKid04 Well-Known Member Established Member

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    Are modded guys running tr7 or tr7ix?
    What gap?
     
  5. me32

    me32 BEASTLY SHELBY GT500 TVS Moderator

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    Depends on boost. 19+ boost TR7.
     
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  6. Chancey

    Chancey Auto Affection Established Member

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    Yep...
     
  7. Norton

    Norton Long-time SVT Enthusiast Established Member

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    Recommended plugs are NGK TR7-IX (Iridium plug) and Motorcraft SP-471 / AGSF12FM1 (Platinum plug).

    IIRC, both should be gapped to .032 for up to 15psi, .028 for 16-19 psi, and .026 for 20+ psi.
     
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  8. 2011 gtcs

    2011 gtcs GT500 poster Established Member

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    I run NGK BR7EF plugs gapped at .28, I'm running 19psi, I change them every 1,500 miles, I know it's total overkill.
     
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  9. Jam421

    Jam421 Jam421 Established Member

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    I'm running the NGK TR7-IX at .028 Gap at 16.5psi Boost. I must admit the car did feel crisper when I swapped them out last season after about 4K miles. If I'm changing every 2-3K miles I may ask about the feasibility of switching to the NGK TR7 but the price difference vs the Iridiums is not that bad. I guess it's worth swapping the plugs out despite the lower miles...as mentioned by Chancy....it's cheap insurance.
     
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  10. PM-Performance

    PM-Performance Active Member Established Member

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    You absolutely do not need to be changing plugs often at all. Honestly even 30-40K is overkill.
    Now that being said in my big power cars, I try to change them yearly because I run the snot out of the car and usually run additives. But to be blatantly honest it is a complete overkill and waste of money, esp on Iridium plugs
     
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  11. PM-Performance

    PM-Performance Active Member Established Member

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    TR7IX is supposedly a better plug for quality idle and part throttle drivability and less random missfire codes.
    You can get some solid deals on these on Amazon
    18-20PSI or so and I run mine at .028
     
  12. Chancey

    Chancey Auto Affection Established Member

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    I am a fan of the TR7ix’s as most everyone is for our cars. But when I bought and installed my upper pulley, intake, tune and 69mm throttle set up, they sent me the NGK BR7EF plugs with the kit. I put them in just to give em’ a try. They have ran just as good for the 2,500 miles I’ve put on them. I am still gonna replace them with the TR7ix’s when I swap them.
     
  13. me32

    me32 BEASTLY SHELBY GT500 TVS Moderator

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    Depends on the plug. I would never recommend running a TR6 or BR7 30k-40k. 10k miles maybe 20k at most.
     
  14. biminiLX

    biminiLX never stock Established Member

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    Who sent you the plugs Chancey?
    Those would be the best choice, especially for high boost.
    The BR series are a NON-projected tip vs the traditional projected tip of the TR series plugs.
    On a boosted application, the better choice is a non-projected tip to prevent spark blow out. The higher the boost the more important.
    I don’t run the Iridium because I change the plugs every year anyway and standard Cooper works.
    -J
     
  15. PM-Performance

    PM-Performance Active Member Established Member

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    what do you really think is going to happen to a plug still being used at 1/4 of its recommended lifespan?
     
  16. me32

    me32 BEASTLY SHELBY GT500 TVS Moderator

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    You have never ran those plugs on a modded terminator or Gt500 for those miles. They start miss firing. Rough idle ect. Your more then welcome to try it on your own so you can actually experience those issues with those plugs.
     
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  17. PM-Performance

    PM-Performance Active Member Established Member

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    I mean, I am sure someone has. lol. Just not me. Like I said I think we all go a little overkill on replacing plugs. But if you have noticed missfires and new plugs fixed it, then I am incorrect on being overkill.
     
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  18. Catmonkey

    Catmonkey I Void Warranties! Premium Member Established Member

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    It's not all that hard to foul out a set of cold plugs unless you run the car hard fairly frequently. I used to have a spark plug cleaner that shot some type of abrasive at the plug to help clean off the electrode and porcelain, which were still basically good, but had fallen off in performance. Probably not a bad idea if you're going to run iridium to clean them when you feel like you need to change the plugs.

    @biminiLX, what plugs in the 7 heat range have a copper core?
     
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  19. SCGallo2

    SCGallo2 Balanced performance Premium Member Established Member

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    I have run both NGK TR6 and TR7IX gapped at .028 for 16-17psi on 93 octane with no additives. For a well-tuned street car frequently run to its full potential, I have found that replacing spark plugs every 2 years or 10,000 miles (whichever comes first) works great for me. I have never experienced poor drivability due to a worn or fouled plug. My engine initially runs smoother after a cold start with the TR6s, but other than that, the difference between the two plugs is undetectable by me. As Chancey brought up, routine inspection of the plugs on a modified Shelby is important, looking for signs of detonation and oil burn in the combustion chamber, to detect an impending catastrophic failure.

    My TR6s start to show wear at 10k miles:
    10k mile TR6.jpg

    My TR7IXs looked good at 10k, could have gone 20k:
    TR7IX 10k miles.jpg
     
  20. MG0h3

    MG0h3 Well-Known Member Premium Member Established Member

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    BR7EF @28 at @20psi on E85

    Changed them at 14k miles

    10k miles at 15psi 600rwhp
    4K miles at whatever 20psi and E on a 2.9 Whipple is.

    Other than coloring, practically looked new. Almost zero wear on either electrode or strap.


    Sent from my iPhone using svtperformance.com
     
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