So in a regular 4.7l with an intake and exhaust, is it better to go with a E3 3.64 or the 3.56 which is a hotter plug. Whats the general rule when determining what type of plug you need?

 

Usually if you want a hotter spark you go with a higher octane fuel. I.e. 91, 93 or the 10-15% ethanol mixture for greater power. The reason for the higher octane is due to risk of pre detonation. If you use a tuner to increase degree of tuning (aggressive tuning) with hotter plugs you have to run a higher octane fuel.

Those of use with boost, ie Superchargers, Turbos or spraying nitrous have to go a range to two ranges colder on our spark plugs. Pre det for us can be much more serious so I use 93 octane fuel, VP M1 Methanol Injection (115 octane fuel) and run NGK colder range plugs.

Here are the plugs I use and the alcohol I spray.
Picture009.jpg

 

So Ill be running my truck with the intake and exhaust, along with the 91 octane tune from SC. Should I go for the 3.54 plugs?
I run 93 octane fuel and will as long as I have the tuner on the truck. If I ever take if off, I would switch back to 87 octane with the stock tune. I want to be able to switch back to the stock tune and 87 octane at any time without having to change the plugs, so I want to put the plug that would work best with both applications.
Thanks.

 

I know with the E3.56 plugs you can switch to the 87 tune with 87 gas without any issues. Thats whats in the Durango and they are awesome. If you shoot E3 an email and ask them, they can give you the best advice. That is what I did with my NGK plugs. I listened to everyones advice and then hit up NGK tech support before making my final decision.

 

Sounds good. Thanks for your help Blown287.

 

i just changed my plugs from the 3923 to the e3.48. when i removed the 3923 after 2 years and 28k they looked perfect. almost brand new except for +.003 in hte gap. (from .040 to .043 on avg). they were very white so i decided to go slightly hotter or back to stock. i was always told they should have a mild coffee color to them, any disagreements?

so far the idle is the same. i dont feel any difference other than my wallet being much lighter. ill see what they look like in 2 years unless i notice something erratic in hte meantime.

in my opinion use the autolites and save your money. make sure to gap them they come all over the place.

 

I definetly need to do something. I doubt the spark plugs have been changed recently if they have been changed ever. My truck has a slightly rough idle every once in a while, so Im hoping its just plugs.
Is this something worth going to the dealer for and just get stock plugs? I think with a coupon I can get new spark plugs and idle adjustment for $80. PS- Im not very confident in myself replacing plugs. I know a little, but I have no idea what to do if a plug is stuck in the head, what to torque the plugs to, ect.

 

You can compare them to these which will give you an idea: http://www.ngksparkplugs.com/techinf...200&country=US

 

thanks for the reference pictures.

my 3923 gapped at .040 in the "N" were are perfect match of the normal. the e3.48 are a different heat range so ill see what they look like. ill check the easiest plug after a while.

the e3.48 is hotter than the 3923, correct? the e48 matches the 3924 and the rc12mcc4


as for the idle issue mine will idle fine at times and then feel a little off on the same trip. let me know iff the dealer ups your idle t solve that issue. i would ask the dealer for the used plugs and take a look at them. my stock plugs had huge discrepencies in the gap. it is not overly difficult but is not straight forward either. for the $80 get a 12" ext, 6" ext, 5/8 spark plug socket, compressed air to blow out crap before you remove the plug and joint. youll also need a 10mm socket to remove stuff in the way. it will take about an hour and i know dealers charge more than 80 an hour so expect to hear that everything needs replaced.

 

If it's the equivalent of the 3924 it should be one heat range hotter.