The Spark Plug Thread

[T_Unit114]

I have seen a metric poo ton of spark plug threads and posts on here and Foolbook groups regarding plugs. I had many of the same questions, but other than some random vague suggestions and "I didn't have problems", none of what I wanted to know was really addressed. So I have decided to create a thread that I will answer the burning question...... WHAT SPARK PLUGS DO I BUY?!?! And for those of us who desire a little more information..... Why do you suggest those?

For the first group who just wants to know what my opinion is NGK 92145 LZFR5CI-11 Laser Iridium Spark Plug is what I decided on after my research.

Disclaimer: none of this research has been independently verified or tested. This is not the spark plug bible and all opinions herein should be taken at face value just as this research has been. Buyer beware. All plugs do come pre gapped but this gap should still be checked before install and if the plug is ever dropped. Your results can and will vary and it is not my responsibility if you don't get what you wanted.


For the rest of you, this is a couple day's work, this is not a master catalog, you will not find every plug available in the furthest corners of the globe. This is not the ultimate showdown. There is however, a method to my madness.


The method:

I found the OEM spark plugs for my 2012 Ram 1500 hemi. SPLZFR5C11. AKA- NGK 92174 LZFR5C-11 Nickel Spark Plug. While Mopar now recommends the use of iridium plugs, these will be found in use and the OEM plugs have a suggested service life of 30k miles. I'm at 170k and began to develop a miss somewhat recently at idle so I'd say mine are about due for a swap. Also noting here that my OEM coils are being replaced with MSD Blaster coil packs. Having 170k miles, these would be on a to do list in the near future anyways.

I went direct to NGK's website, Entered my vehicle information and it pulled up a list of plugs that matched. Being that I only had a few hours and that NGK makes the OEM plugs for my basic hemi as well as the SRT models, I was comfortable trusting them. I made sure that all options listed were 14x1.25 thread, 26.5mm reach, with a temp rating of 5 and a 5k ohm resistance. This ensured that all standards were met for the plug to function in cylinder. The rest was about longevity and quality of spark.

The madness:

The following posts will be by brand, with all options offered that meet the above listed criteria

Yes, I understand that colder and hotter plugs may be used, but the goal here was to find the best stock replacement plug I could for my buck. There may be better plugs, there may be cheaper plugs. I will not list price because prices constantly change and anyone that has bothered to read this far, is going to be shopping around with an extra tab open reserved for finding coupon codes. (I'm the same way)

That is where I'll end the intro to this thread. Please Give me a couple days to get some more brands posted up and do some more digging. I'm planning on doing posts for NGK, Autolite, Bosch, E3, Champion, and a couple others right away.........If they meet the above criteria of thread, reach, heat rating, and resistance rating. I will also provide a recommendation at the top of each brand group to allow the thread skimmers to get their info faster.

Thanks!
T-Unit

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[RedSRT4Me]

NGK 4469.

 

[T_Unit114]

First is NGK. They not only make the OEM plugs for my Hemi, but they also supply the plugs for the 6.1 gen 3 Hemi engines.

I chose to install NGK 92145 LZFR5CI-11 Laser Iridium Spark Plug. Reasoning: 100k mile life expectancy, copper core, iridium inner and outer electrodes, platinum ground electrode. Price is about twice as much as the factory plugs with over 3x the projected replacement interval meaning they will likely be in this truck when it goes to the scrap yard.

Starting from the baseline is the list of NGK offerings with specs listed in pictures.

NGK 92174 LZFR5C-11 Nickel Spark Plug
This is the OEM at the time of manufacture. According to NGK, Mopar now recommends an iridium plug in place of this when doing maintenance.


NGK 5018 LFR5AGP G-Power Platinum Spark Plug


NGK 4469 LFR5AIX-11 Iridium IX Spark Plug


NGK 92145 LZFR5CI-11 Laser Iridium Spark Plug Recommended by FCA for extended service intervals.
This is my personal pick. And what is going to be installed in my truck.


NGK 96355 LFR5AHX Ruthenium HX Plug
I did not go this route due to the extra cost for a plug with a wildly variable life expectancy. I can't justify 3x the price for a 24.9% chance it could last 3x as long. Those are not betting odds for me. Those numbers could always change.


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[GTyankee]

RockAuto did their research too

somewhere above you mentioned the
SPLZFR5C11
SP = Spark Plug & is only used by the dealership, MOPAR products

LZFR5C11 is the NGK #

 

[crackerjack1957]

Let us know how the laser iridium plugs work with those older 2012 coils........they were designed for the nickle/copper.

 

[GIJoe2010]

In 14 is where Ram upgraded to the newer/better coils and went with the NGK Iridiums, and that’s what I replaced mine with and no issues.

 

[Wild one]

First is NGK. They not only make the OEM plugs for my Hemi, but they also supply the plugs for the 6.1 gen 3 Hemi engines.

I chose to install NGK 92145 LZFR5CI-11 Laser Iridium Spark Plug. Reasoning: 100k mile life expectancy, copper core, iridium inner and outer electrodes, platinum ground electrode. Price is about twice as much as the factory plugs with over 3x the projected replacement interval meaning they will likely be in this truck when it goes to the scrap yard.

Starting from the baseline is the list of NGK offerings with specs listed in pictures.

NGK 92174 LZFR5C-11 Nickel Spark Plug
This is the OEM at the time of manufacture. According to NGK, Mopar now recommends an iridium plug in place of this when doing maintenance.


NGK 5018 LFR5AGP G-Power Platinum Spark Plug


NGK 4469 LFR5AIX-11 Iridium IX Spark Plug


NGK 92145 LZFR5CI-11 Laser Iridium Spark Plug Recommended by FCA for extended service intervals.
This is my personal pick. And what is going to be installed in my truck.


NGK 96355 LFR5AHX Ruthenium HX Plug
I did not go this route due to the extra cost for a plug with a wildly variable life expectancy. I can't justify 3x the price for a 24.9% chance it could last 3x as long. Those are not betting odds for me. Those numbers could always change.


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If you find your original coils a bit weak on output,a stop gap measure is to close up the gap slightly to somewhere around 0.038/39",a smaller gap takes the load off the coils and is easier to fire,but there's a good chance your coils if they're still in decent shape will have enough juice to fire the later irridium plugs. Check the gaps before install,i've found them to have a fair bit of varience.Avoid plugs off Ebay or Amazon,especially if they're way cheaper then anywhere else,good chance they're Chinese knock-offs.,and not the same quality of plug.

 

[T_Unit114]

RockAuto did their research too

somewhere above you mentioned the
SPLZFR5C11
SP = Spark Plug & is only used by the dealership, MOPAR products

LZFR5C11 is the NGK #

This is true. Being that I was directly referencing a Mopar part, I used the Mopar part designation.

Let us know how the laser iridium plugs work with those older 2012 coils........they were designed for the nickle/copper.

I won't be able to do so as The OEM coils are being swapped for a set of MSD blaster coils. I've used them on a few different rides over the years with a couple on Hemi engines and they did well. I would imagine results would vary based on mileage and hours if you kept the OEM coils but with my mileage, and planned use for the truck this year, I decided to do all ignition side in one shot.

If you find your original coils a bit weak on output,a stop gap measure is to close up the gap slightly to somewhere around 0.038/39",a smaller gap takes the load off the coils and is easier to fire,but there's a good chance your coils if they're still in decent shape will have enough juice to fire the later irridium plugs. Check the gaps before install,i've found them to have a fair bit of varience.Avoid plugs off Ebay or Amazon,especially if they're way cheaper then anywhere else,good chance they're Chinese knock-offs.,and not the same quality of plug.

Coils came from Summit Racing, plugs will be store or dealership purchases. I'm trying to get them installed today after work. I always suggest confirming gap. It's very easy to do and it will make a noticable difference in performance if the gap is far enough off.

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[crackerjack1957]

Well damn......wasted my typing fingers because there was no mention of a coil change out prior......LoL

 

[Cheaptubes]

In 14 is where Ram upgraded to the newer/better coils and went with the NGK Iridiums, and that’s what I replaced mine with and no issues.

I just got a 14, gonna try same plugs. All good with yours?

 

[EdGs]

Put the NGK 92145 in my 2015 Hemi. No issues. Got the Gearwrench 80546 magnetic spark plug tool. That, and a top-side creeper made life simple

My only issue was a sore abdomen from laying my fat *** on the creeper doing the job.....lol.

 

[GIJoe2010]

I just got a 14, gonna try same plugs. All good with yours?

No issues, and get the gear wrench mentioned above and you’ll be good. RockAuto has the cheapest price and fastest shipping on the spark plugs as well.

 

[Ramhergood]

Has anyone tried these?
Bosch Fine Wire Double Iridium Spark Plug | BOS 9654 | Qty: 16