78 replies to this topic

[Andy@PWR]

Here is some info I obtained today regarding spark plugs.

We have a ton of customers who use 1 step colder plugs on their srt8's for use with strokers or Superchargers or basically any combination that nets them around 500rwhp. The plug most often used is listed below.
NGK-LZTR6AIX-13- Stock number 2315- 1 step colder for 6.1
Projected tip, Iridium

Now that we have been porting 6.4L heads left and right, I have a ton of 6.4L spark plugs in a box and I wanted to determine how they compared. Here is that part number.
NGK-LZTR6AP-11EG

The 6.4L plug is the same heat range as the 2315 plug listed above which makes it a good plug for 500rwhp applications. The differences are that the 6.4L plug is platinum and not iridium, it comes gapped at .044" instead of .052" like the 2315 plug above and it has a 10k ohm resistor instead of a 5k ohm resistor. Evidently 5k is industry standard but 10k is supposed to increase plug life.

Anyhow, just wanted to let everyone know that there is a new option available for a 1-step colder srt8 plug for 500rwhp applications. This will not work with the Eagle cylinder head as it has a washered seat plug and not a tapered seat plug like the 6.1 and 6.4.



For Eagle Heads
Stock Eagle Plug: NGK SPLZFR5C11
1 Step Colder: NGK ILZFR6D11 (Stock #1208) or NGK LFR6AIX-11 (Stock #6619)
1.5 Step Colder: Brisk ER14YS
2 Steps Colder: NGK LFR7AIX (Stock #2309)

[StevoHemi]

Andy, whats your opinion on running a plug two steps colder with 5.7 vvt with a maggie, shorties and flows? Does changing plugs two steps colder affect the tune?

Stevo

[Andy@PWR]

I think thats too cold. It will affect the tune somewhat and it might mis-fire due to being too cold.

[StevoHemi]

Thanks Andy. I will just go one step.

Cheers,

Stevo

[dodgetime]

donka Andy good info

[HemiSam]

Keep in mind that's gonna read two steps colder than what a stock R/T says in the manual, Stevo. Don't pay that any mind. They give you the same plug for an R/T as they do an SRT8 at the parts counter at the stealership. Just like we discussed.

HemiSam

[StevoHemi]

Thanks Sam. I am going to install the number you and Andy suggested NGK-LZTR6AIX-13.

Stevo

[HemiSam]

Don't forget to tighten that gap a bit, Stevo. Some anti-seize on the threads won't hurt a bit either

Good luck, bro.

HeimSam

[Andy@PWR]

This will not work with the Eagle cylinder head as it has a washered seat plug and not a tapered seat plug like the 6.1 and 6.4.

Thanks Sam. I am going to install the number you and Andy suggested NGK-LZTR6AIX-13.

Stevo

Don't forget to tighten that gap a bit, Stevo. Some anti-seize on the threads won't hurt a bit either

Good luck, bro.

HeimSam

You cant use these plugs in an eagle head.

[Andy@PWR]

Stock Eagle Plug: NGK SPLZFR5C11
1 Step Colder: NGK ILZFR6D11 (Stock #1208) or NGK LFR6AIX-11 (Stock #6619)
1.5 Step Colder: Brisk ER14YS
2 Steps Colder: NGK LFR7AIX (Stock #2309)

[HemiSam]

You cant use these plugs in an eagle head.

Interesting... I've used both of these in my Eagle heads and checked with A.J. on them before hand.

LZTR7AIX-13

LZTR6AIX-13




HemiSam

[Andy@PWR]

Just because your using them, doesnt mean its correct. The Eagle head uses a washered seat plug. The 6.1 and 6.4 uses a tapered seat plug. You can also use a Briggs & Stratton plug, but you shouldnt.

The second cylinder over has an eagle plug in the 6.4 head. You can see how it doesnt even protrude into the chamber. I think I have an eagle head laying around, I will take a pic of the two different plugs as well as how they fit when installed.

[HemiSam]

I'd like to see that, Andy. I'm running Brisks now.

HemiSam

[toofart]

Great info Andy.

[Knownman]

Kenne Bell asks for NGK 4306's with a .035" gap on the 6.1 kits with a 2.8 liquid cooled. Adam has asked me to tighten that gap up to .032" for the tune. What's the big difference on gaps and materials of plugs?

I also have a full set (16) of unopened iridium Denso plugs if anyone whants them. I'll let em go for a good price.

[Speedy]

The Platinum and Iridium plugs are supposed to last longer, but most tuners like the copper plugs for supercharged applications from what I've seen.

The reason you tighten the gap on supercharged motors is to prevent the spark from being blown out by the air being forced in by the blower.

This also may be helpful. It breaks down a NGK spark plug part number.

[Andy@PWR]

What do you mean by standard? Copper is the material of choice for most.

[StevoHemi]

Ok.... getting confused here. Lets start with the head. I presume the "Eagle" head is an aftermarket piece like Indy? Or does Mutha Mopar call her heads Eagle?

Does this plug (NGK-LZTR6AIX-13.) work in a 5.7 stock head/Maggie equipped? It won't be shallow like in Andy's pic? We should do a quick poll to see who is running what and in what style of motor.

Not trying to be a pain in the ass.

BTW, luv threads like this one. Thanks for starting Andy.

Stevo

[Andy@PWR]

Eagle head is an 09-Current 5.7 head. If you have an 09-current 5.7, you have an Eagle motor and you need washered seat plugs.

Eagle plugs at top and Apache/6.1 plugs on bottom.

Ok.... getting confused here. Lets start with the head. I presume the "Eagle" head is an aftermarket piece like Indy? Or does Mutha Mopar call her heads Eagle?

Does this plug (NGK-LZTR6AIX-13.) work in a 5.7 stock head/Maggie equipped? It won't be shallow like in Andy's pic? We should do a quick poll to see who is running what and in what style of motor.

Not trying to be a pain in the ass.

BTW, luv threads like this one. Thanks for starting Andy.

Stevo

You need one of these. I recomend the Brisk ER14YS or NGK LFR6AIX-11

For Eagle Heads
Stock Eagle Plug: NGK SPLZFR5C11
1 Step Colder: NGK ILZFR6D11 (Stock #1208) or NGK LFR6AIX-11 (Stock #6619)
1.5 Step Colder: Brisk ER14YS
2 Steps Colder: NGK LFR7AIX (Stock #2309)

[StevoHemi]

Thanks Andy! Thanks Sam! I will get a set by next weekend and throw them in.

Stevo