Hello all, I’ve purchased a 2005 E55, I’m in the process of changing all that is broken and all that in need of a replacement. One of the items on my change list is spark plugs and ignition coil wire set. I would like after a few months of driving the car to make sure no problem arrives before doing performance upgrades. I plan on installing smaller supercharger pulley, headers, tune, bigger heat exchanger and a few other things.

My question is…..is it ok to run the colder spark plugs now with the car being Stock? I’m trying not to have to change spark plugs out twice but don’t know if the colder spark plugs will cause any issues with the car in it’s current state (Stock) I was told when I do the performance upgrade that I will need colder spark plugs. Is this even true?

 

Hi there, it's not a requirement especially if you get a good tune and are running headers which help purge heat out of your cylinders more efficiently than the OE log manifolds. Depending on how small you go on your pulley 1 step cooler plug would be good to go. I would put them in now and mod later. One heat range is not that drastic. The cooler heat range will not burn off deposits though as well. I plan on running NGKs Ruthenium HX line when I change my plugs out. LFR6BHX is the stock heat range in that line. Putting a 7 where the 6 is would be one step colder.

 

Thanks for the info

 

has anyone found lfr7bhx plugs??
I have only seen lfer7bhx or the stock lfr6bhx
the lfer7bhx has a 1000ohm resistance vs the stock 5000

 

This is a few months old but thought I would post.
You do not need a colder plug and if you have a climate that has hot/cold weather you should always keep the stock heat range plugs in especially in cold climates where the engine takes a long time to heat up. A hotter plug will stay cleaner during warm up periods.
Even with performance engines you want to keep as much heat in the chamber as possible for maximum power... power is made through thermal energy. Coated pistons and chambers really raise the power potential by keeping the heat in the chamber and not letting it absorb through the head or piston top but you need to be very mindful of temperatures...EGT and AFR to be safe.
A colder plug will allow you to be "off" with your tune a little and pull more heat out of the spark plug tip for a little more protection from detonation and should only be used with high boost and or Nitrous.
Gives you a little safety margin.
The only way to know if your plus are correct for your application is "read" them to see where the heat range is on the porcelain. The electrode will show where the timing is.

 

thanks for the lesson. What do you consider high boost? Would that also apply to a fixed pulley vs clutched since the engine is always seeing boost?
Has anyone found a LFR7BHX plug? I ordered the LFER7BHX and will be installing those.

 

No difference in fixed or clutch, no relavance.
Boost wise 13-14 or so and up I would say

 

It's generally not recommended to use colder spark plugs on a stock engine as it may lead to issues. Wait until you've completed your performance upgrades.