Change Of Plugs ?

me32

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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:
View attachment 1630497

My TR7IXs looked good at 10k, could have gone 20k:
View attachment 1630498

Looks to be expected at the milage
 

biminiLX

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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?

https://www.summitracing.com/parts/ngk-3346

This is what I run.
22psi E85
I’d actually like to try heat range 8s
-J
 

Catmonkey

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This is what I run.
22psi E85
I’d actually like to try heat range 8s
-J
Thanks, J. I figured it might be these, but I haven't heard of anyone actually using them yet. If any needs the 8 range, it's likely you.
 

biminiLX

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Thanks, J. I figured it might be these, but I haven't heard of anyone actually using them yet. If any needs the 8 range, it's likely you.
Thanks Cat. I do plan on trying the 8s this year as we found the limit of TR6s on my brothers turbo E85 Terminator.
I think I’ve learned E85 on decent boost and timing let’s you run a hotter plug than gas fuel. The hotter plugs supposedly run better off boost, but I’ve ran 8-9 range on my turbo 427Ws, and never had plug fouling problems.
People tend to forget heat range and also don’t realize the 5.8 moved to a slightly colder 7 plug so if you’re turning the wick up on pump gas or race fuel, go to a heat range 8 or a quality NON-projected tip 7 you change more regularly.
I always choose non-projected plugs on boosted cars.
-J
 

Chancey

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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
Thanks biminiLX. Sorry man, I just noticed your post. Lethal performance sent me the plugs with my pulley swap, throttle body, and lund tune kit. I will keep running them then. They seem to run just as well as the tr7’s.
 

VNMOUS1

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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.
15k unless you are using octane booster, e85 or beating the piss out of it

Sent from my SM-N975U using Tapatalk
 

blue 07

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I have changed from stock plugs to NGK 7IRX after having some blower work done over the winter, and have issues with misfire codes-p300- and will be switching back to stock plugs
 

Norton

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I have changed from stock plugs to NGK 7IRX after having some blower work done over the winter, and have issues with misfire codes-p300- and will be switching back to stock plugs
Interesting. Assume blower was ported? What, if any, other performance mods do you run? What does your tuner recommend?

FWIW, I installed NGK TR7-IX plugs in conjunction with the JLT 127mm CF CAI, CFM Twin Jet 67mm TB, VMP 2.4" Upper, 90mm Idler, BPS Oversized & Ported Plenum/Elbow, VMP Triple-Pass Dual-Fan H/E, and Reische 170' Tstat. That was about 3yrs, 10K miles, and several (1/2 mile) race passes ago. Have never thrown a misfire code.
 

darksykal

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I have changed from stock plugs to NGK 7IRX after having some blower work done over the winter, and have issues with misfire codes-p300- and will be switching back to stock plugs
i got the same codes here on those plugs gapped at 0.27
tried 2 sets and still get it intermittently

my tuner even hooked my car up to this machine to detect actual misfires and got 0
 

PM-Performance

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Yea this is strange. The TR7IX is usually THE goto plug to fix the random missfire issues and idle issues the other plugs have been known to cause.
 

biminiLX

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I have changed from stock plugs to NGK 7IRX after having some blower work done over the winter, and have issues with misfire codes-p300- and will be switching back to stock plugs
You can experiment going back to stock plugs, but I’d say it could be related to the work and blower swap R&R.
That or your car is just very sensitive.
What year car? Miles? Common maintenance done like fuel filter?
Just throwing a few things out as the TR7ix is a good plug.
-J
 

blue 07

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Interesting. Assume blower was ported? What, if any, other performance mods do you run? What does your tuner recommend?

FWIW, I installed NGK TR7-IX plugs in conjunction with the JLT 127mm CF CAI, CFM Twin Jet 67mm TB, VMP 2.4" Upper, 90mm Idler, BPS Oversized & Ported Plenum/Elbow, VMP Triple-Pass Dual-Fan H/E, and Reische 170' Tstat. That was about 3yrs, 10K miles, and several (1/2 mile) race passes ago. Have never thrown a misfire code.
Yup, blower and elbow was ported and polished over the winter. Last year just the elbow was done when TB was added, this time slightly more was honed out
Other Performance mods include-67 mm VMP throttle body, JLT Big Air CAI, VMP 2.4 upper, 90 mm idler pulley, Metco Aux Idler -
Tuner keeps throwing p300 misfire code so my tuner guy pulled out the code so wont happen, failed NH inspection
Pete at Performance Dyno has seen this many times, switching back to stock plugs has helped in most cases, never had the code till plug change, and cant get an inspection sticker with the misfire code. Putting it on the dyno next Thursday to make sure all parameters are good and see what the winter mods have done to the hp and tq. Will post results then.
 

blue 07

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You can experiment going back to stock plugs, but I’d say it could be related to the work and blower swap R&R.
That or your car is just very sensitive.
What year car? Miles? Common maintenance done like fuel filter?
Just throwing a few things out as the TR7ix is a good plug.
-J
It is sensitive for whatever reason, 3rd year in a row with some type of inspection issue after winter storage. Usually drive cycles need to be accomplished for inspection purposes, battery issues have been the problem from motor work being done over the winters
2013 GT500, miles 24,980. Babied all the time, put up winter months (5-6 months at a time), usually drive 2500 miles per year, usual maint. done, fuel filter not been changed yet
Ive heard nothing but good things about the plugs but the misfire codes are driving me crazy, especially since I cant get it inspected ! For $50 Im buying new Motocraft plugs, old ones are fine but will put new ones in and see what happens.
What should the oem plugs be gaped at ? NGK I have are gapped at 28
 

PM-Performance

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The gap really doesn't have to do as much with the plug type and more for boost levels. I would say under 20PSI .028 is fine.
If it blows out for some reason, just tighten the gap a little. There really is no ill effect of running too tight a gap, other than maybe replacing plugs a little sooner. It sounds like most replace atleast once a year anyway.
Too open a gap will cause blowout though and that just sucks.
 

Ray Lucca

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You could try the Motorcraft SP-471 (AGSF12FM1) gapped at 28 or 30 with your Mods, Colder than Stock. Good luck chasing it down..
 

blue 07

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The gap really doesn't have to do as much with the plug type and more for boost levels. I would say under 20PSI .028 is fine.
If it blows out for some reason, just tighten the gap a little. There really is no ill effect of running too tight a gap, other than maybe replacing plugs a little sooner. It sounds like most replace atleast once a year anyway.
Too open a gap will cause blowout though and that just sucks.
My last dyno run I was at 17.9 lbs. last year. Added a Metco aux idler for belt slippage so maybe a little more now. We'll check on dyno next week
 

PM-Performance

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My last dyno run I was at 17.9 lbs. last year. Added a Metco aux idler for belt slippage so maybe a little more now. We'll check on dyno next week
Its really moot. I would start at .028 and work down if you have blowout. But tighter gap even by a little more won't really be much an issue to ensure you wont have to redo it again.
I would do this stuff before you get to the dyno as you are paying for the time to change things on the dyno where as you could just do a pull and check for blowout later.
Its not really an exact science, but I start on the smaller side because I rather not risk spark blowout and have to do it again.
 

Jam421

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As Bimini & VNMOUS are suggesting just gapped my new BR7EF's to .028 with my 16.5psi....will pull my NGK 7 IRX's soon which only have 2,600 miles on them. I intend to swap these out every season because as mentioned previously my car felt crisp & clean each season despite such low miles on the Iridiums. Thnx Fellas !
 

little-dw

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speaking of spark plugs, what is the recommended shelf life of them?

I have a set of TR7IX that I got from someone who sold their GT500 and they are brand new in the box, only 3 years old. I googled online and it would seem fine to use them, but would like to know GT500 owner's opinions as well.
 

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