Spark Plugs upgrade LFR6A or LFR7AIX

[ElahiStrength]

Hi Folks,


A newbie to the forum,

I am looking for cooler spark plugs and have been advised to go for the LFR7AIX NGK plugs for my cls 55 amg - is this correct and the right fitment?

I know the normal ones are LFR6A - car will be running around the 620 bhp + range.

 

[grober]

Without knowing the exact age of your car its difficult to know the answer. You could have the M113 3 valve engine or the later M273 4 valve engine with its inherent timing gear problems? Iirc the LFR6A is the standard copper core plug for the earlier M113 engine which will have 16 plugs! Whereas the LFR7A iX is a fine tipped iridium plug--- IRIDIUM PLUGS in the equivalent heat range will run cooler and have a longer life.

 

[grober]

Without knowing the exact age of your car its difficult to know the answer. You could have the M113 3 valve engine or the later M273 4 valve engine with its inherent timing gear problems? Iirc the LFR6A is the standard copper core plug for the earlier M113 engine which will have 16 plugs! Whereas the LFR7A iX is a fine tipped iridium plug--- IRIDIUM PLUGS in the equivalent heat range will run cooler and have a longer life.

The 7 would indicate a grade cooler a plug than 6.
NGK QUOTE:-
Heat Range Selection

Let's make this really simple: when you need your engine to run a little cooler, run a colder plug. When you need your engine to run a little hotter, run a hotter spark plug. However, NGK Spark Plugs strongly cautions people that going to a hotter spark plug can sometimes mask a serious symptom of another problem that can lead to engine damage. Be very careful with heat ranges. If you are changing heat ranges, contact NGK Spark Plugs tech support for professional guidance
With modified engines (those engines that have increased their compression,) more heat is a by-product of the added power that normally comes with increased compression. In short, select one heat range colder for every 75-100 hp you add, or when you significantly raise compression. Also remember to retard the timing a little and to increase fuel enrichment and octane. These tips are critical when adding forced induction (turbos, superchargers or nitrous kits), and failure to address ALL of these areas will virtually guarantee engine damage.


- See more at: NGK Spark Plugs

 

[Andrew W]

http://youtu.be/2Z1jDdSYKPA
I've read good things about these , this guy loves them , same engine as yours and mine .

 

[Andrew W]

Let me know if you find some .

 

[ElahiStrength]

Appreciate all the replies folks, how would I find what model my engine?

Ill speak to NGK Tomorrow and ill speak to ACID from MSL as well

 

[grober]

Appreciate all the replies folks, how would I find what model my engine?

Ill speak to NGK Tomorrow and ill speak to ACID from MSL as well

The MSL guys will keep you right with their experience of remapping big Merc engines.
If your engine has two spark plugs per cylinder its a M113 if its just got one plug per cylinder its the later M273. If you check your vehicle log book it should give you the engine number---- it will start 113********* or 273*********

 

[ElahiStrength]

Thanks for the replies and input from everyone, much appreciated
.

 

[E55MO]

I have LFR6A curently. I am only running 530bhp

 

[ElahiStrength]

I thought with 600 bhp the next ones cooler would be better

 

[Andrew W]

If it's a CLS55 its the 5.4 supercharged M113 3 valve engine regardless of year , it's the only
engine in this model range , it then changed to
a 6.2 N/A engine .known as a CLS63 .

 

[ElahiStrength]

Thanks Andrew, in that case its the M113.