yea copper, and so are the BKR6Es I replace them every 5000

6 is stock heat range
7 one colder
8 two colder

 

^^^add to that

e = copper, you'll have to check/change more often, but best conductor, and can gap as you like

eix = iridium, longer lasting, and not suppose to gap

to help with any confusion

 

GM doent recommend changeing ur plugs till a 100,000 anyway.

 

Gm also recommends only 91 octane.......nuff said

Any moron knows you dont use platinum plugs with boost

 

ok yeah i misread i thought you said that the bkr6es were copper and the 7s werent. i was confizzled.

 

This is a stupid argument. I had autozone call NGK (a while ago) and they stated that brk7e is the one step colder plug for the ion redline and cobalt ss/sc. The ions came with ngk-r plugs from the factory (I guess 6e?). Iridiums are not factory replacement, factory is copper plugs. It really shouldn't be this hard to figure out. Since people have been changing plugs for years it's autolite 3922 or brk7e or brk7eix for one step colder plugs. Autolites run worse than the ngk's in my car but it's different for everyone. Denso makes plugs too I believe it's ix22 for the 1 step colder but they don't make copper plugs that fit to my knowledge.

 

so why go to a colder plug when using supercharger applications? wouldnt one want to to use a warmer spark

 

No. The more compression and fuel you dump into the engine, the hotter it gets. You run a colder spark plug to pull more heat out of the combustion chamber and into the coolant. Colder plug = more heat removed from combustion chamber.

Engines are designed to have the best combustion at 500C - 850C. If the combustion chamber is below that you may not be able to burn all the fuel. If it is above then you get detonation. A one step colder plug typically reduces the combustion chamber tempuratures by 75C - 100C.

 

^^ Good explanation!

Most people think a spark plug's only function is to make a spark. Really they are extremely important in the heat transfer in the cylinder head.

With that being said, what is the guidline on when to go from a stock heat range to one or two steps colder?

I run a 2.7" pulley with a custom tune on the BKR8EIX (2 step colder Iridium NGK plugs) and the car seems to run great except for a few occasional random cylinder misfires, which the 60 pound injectors are probably to blame. (they don't flow well at low rpms)

So do you think 2 step colder is overkill for a 2.7" pullied car?

 

I would think that 2 steps colder maybe a little much for a 2.7 pullied car, but the problem with combustion chamber tempuratures is that there is really no way to tell what they are. You pretty much have to play a guessing game. If I had to guess, I would say that you could probably get away with running 1 step colder with a 2.7, but it maybe close enough that you can get away with 2 steps colder. It would also depend on what cooling mods you have done as well to keep IAT2 down.

 

so i have 2step colder and i have a 2.8, cams plus shitloads of other mods thats overkill???

 

It all depends. Since there is no way to know what the temps are like in the combustion chamber, all you can do is guess. If you think your car is putting out 300hp or more at the crank, then you may need 2 step colder plugs. Some mods, like meth, by cooling the charge air also will help keep combustion chamber temps down therefore allowing you to run a hotter plug.