Which spark plug for boosted 4th Gen?

I recently purchased a Ripp Supercharger and want to know what spark plugs to use in a boosted 4th gen hemi. I've gotten feedback from several members saying to use either the NGK 4306 copper plugs or NGK Iridium LFR6AIX-11 plugs.

I personally have always stuck with the oem copper plugs, but did not know if iridium plugs are preferred for boosted applications.

I'd like to hear from the guys and gals with boosted trucks what plugs they are using. Thanks!

Just asking what did ripp tell you to run in it? I would think they should know best if they did all the r&d they should know exactly what you need to run.

I posted the question in the Ripp Supercharger thread, but haven't heard back. The instructions merely say to run NGK plugs one stage colder than oem, but does not specify between copper or iridium.

There won't be a big difference between the copper or iridium except longevity of the plugs. The iridium's won't burn out as fast as the copper tips do. You could also look at the non-projected plugs from Brisk as they are able to dissipate heat faster than a projected tipped-plug can, which is important with both boost and nitrous.

I used the Denso 3381 plugs with a 50shot all the way up to a 175 shot with no issues or detonation. I plan on using them when I recieve my Ripp Kit. They are 1 Step colder and copper

Decided to check out the "other" supercharger manufacturers and see what plugs they recommend using with their superchargers. According to Kenne Bell's website, they recommend the "NGK-4306" for their 2008-2010 5.7 and 6.1 Hemi Superchargers. So unless Ripp specifically says they've tried the 4306 plugs and they did not work as well as the iridium plugs, it looks like I am going to stick with the 4306.

Question: will the 4306's cause any problems if I install them and drive around before installing the supercharger? My mods so far are Diablo trinity 91 octane custom tune by hemifever, ARH 1 3/4 headers and cats, magnaflow, 87mm Moe's TB, AirAid intake, 180 degree tstat, V6 fan mod.

you can't run the ngk4306 it is too short of a plug.
Use the Denso 3381

Thanks for the heads up fasthemiram05. Several people have recommended the NGK 4306, but maybe they did not realize I have a 2011 if that is the cutoff year that makes them too short.

Where did you buy your Denso 3381's? I looked online and cheapest I could find them was $5.02/plug.

i got them on rock auto

you can find a ngk equivalent by going on their website

Do the Denso's need to be changed every 30,000 like the oems?

id run the iridium plugs

Originally Posted by fasthemiram05

you can't run the ngk4306 it is too short of a plug.
Use the Denso 3381

I run the NGK 4306 with my blower setup.

KarateMan21 - are the 2009 5.7 motors different than my 2011? I wonder why the 4306's would work for you, but not for fasthemiram05?

Fasthemiram05 - did you try the 4306 in your 2011 express, or your 2012? I'm wondering if something changed in 2012.

The 4306 is the wrong plug for Eagle heads as it has a 'tapered seat' (like the pre-'09 5.7 and 6.1 heads). The Eagle and Apache heads are designed for a 'gasket' or 'washered seat' plug. I went through this looking for a plug for nitrous with Eagle heads and the following is what I found on another forum...

NGK SPLZFR5C11SP = platinum;*L = thread reach 26.5mm;*Z = extended projected tip;*F = 14mm thread, 19mm reach, 5/8" hex, gasket/washered seat;*R = resistor;*5 = HR 5;*C = firing end construction;*11 = 1.1mm gap- Application: 5.7 Eagle OEM – This is what Chrysler puts in- Using these specs, I'm looking for something colder

NGK ILZFR6D11 (Stock #1208)I = Iridium;*L = thread reach 26.5mm;*Z = extended projected tip;*F = 14mm thread, 19mm reach, 5/8" hex, gasket/washered seat;*R = resistor;*6 = HR 6;*D = firing end construction;*11 = 1.1mm gap- Application: 2006/2007 BMW L6 3.0L- One step colder than OEM plug- Would be perfect if it weren't twice the price of everything else and nowhere to be found!

NGK LFR6AIX-11 (Stock #6619)Iridium IX Plug,*14mm Thread Size,*26.5mm (1.04") Reach,*5/8" (16mm) Hex Size,*Gasket Seat,*Resistor,*Projected Tip,*Fine Wire (0.6mm) Iridium Center Electrode,*Tapered Cut Ground Electrode,*.043" (1.1mm) Gap,*Heat Range 6- This would work fine- One step colder than OEM

NGK LFR7AIX (Stock #2309)IridiumIridium IX Plug,*14mm Thread Size,*26.5mm (1.04") Reach,*5/8" (16mm) Hex Size,*Gasket Seat,*Resistor,*Projected Tip,*Fine Wire (0.6mm) Iridium Center Electrode,*Tapered Cut Ground Electrode,*.031" (0.8mm) Gap,*Heat Range 7- This would work fine and can be re-gapped as high as .039" as NGK does not recommend re-gapping > +/- .008”*- Two steps colder than OEM

BRISK ER14YSE = Gasket Seat, 14mm Thread Size, 26.5mm (1.04") Reach, 5/8" (16mm) Hex SizeR = Resistor14 = Heat Range (Different scale than that used by NGK – Brisk considers this about 1.5 steps colder than the OEM NGK plugY = Projected TipS = Silver Center Electrode,- This is the plug that I chose for my 419 CID, 11: 1 compression, 480RWHP (est), NA stroker- 1.5 steps colder than OEM- If it didn't have a 'Projected Tip', it would be considered 2 steps colder- Brisk recommends that I gap it between .032" and .035"

Denso 3381 14mm Thread, 26.5mm (1.04") Reach, 5/8" (16mm) Hex Size, Gasket Seat, Resistor, Solid Terminal, Projected Electrodes, U-Groove Ground Electrodes, .044" (1.1mm) Gap

Damn! That is some good info there. Thanks. So you personally will be running the Denso 3381 in your 2012 with the ripp supercharger when the tuning is available?

I called RIPP and made my payment and will be shipping out today.

I talked to him about the sparkplugs and he told me that they do not come with the kit.
On their Ram, they pulled the stocks and changed the gap to the one in the instructions (i think its 0.325).

I am sure no matter what, we will be a step ahead with stage colder plugs

Yes I will be running them...

They are 2.86 on RockAuto.com

Just talked to Matt and will be getting a set of the NGK G-Power 3381 (1 Step-Colder) Copper plugs.

I just sent him an email about those... they are a tapered seat like the 03-08 hemi heads.
They are incorrectly listed