Spark plugs

Hey I am going to be buying iridium plugs for my car. Now I've already done the reasearch on them So I know a decent amount about them and how well they'll suit my application. The question I have is

what's the difference between these two numbers

BCPR5EIX-11
BCPR6EIX-11

both of the plugs above are NGK Do the 6 and 5 represent different heat ranges? If so is one for the exhaust side while the other is for the intake side? Any help would be greatly appreciated

I am buying these fromhere (http://www.sparkplugs.com/results_app.asp?productTypeID=1&AAIA=1208629) There is also a DENSO one but i think it's a little expensive and doesn't seem to have anything the NGK's don't have.

Yes, the different numbers indicate different heat ranges. The #6 will be a colder plug than the #5. Not sure about whether the intake and exhaust plugs are the same or different.

Well I guess I should go for a colder plug being that will be running a tad more boost. Thinking about it I don't know why the heat ranges would be different they're both in the same cylinder and defeat the purposes of the colder plug.

Thanks!!

They are different heat ranges for each side...........
Intake side is 6
Exhaust side is 5
If your going to use a colder plug only go up 1 heat range on each side.........intake 7, exhaust 6....otherwise you may run into fouling problem which you still might only going up one.
On my old motor I went up one heat range on each side using Denso iridiums, and they fouled up pretty quick......and I didn't notice that it helped any either.....still got detonation the same as with using the stock heat ranges.
On my new motor with 600 miles, I am using NGKs iridiums with the 6 intake, 5 exhaust heat ranges, and so far they are perfectly clean. Haven't cranked up the boost yet so I don't know where detonation will start.
I got my plugs from www.sparkplugs.com along with my NGK wires....and they had pretty good prices, and delivery was pretty quick too.

http://www.clubplug.net has better prices on the plugs that is where i just got mine from. The NGK wires are cheaper through NOPI than even sparkplugs.com

Actuallty the wires ended up being cheaper through sparkplugs.com vs Nopi.com by a few dollars after factoring in the shipping.......
Nopi was $29 plus $10 for shipping
Sparkplugs.com I got them for $31 and $6 for shipping

eh I got magnacor wires them and the spark plugs should come at around the same time.

Ok, this has partially been covered, and partially not. The heat ranges DO matter...and this depends heavily on the climate to which the engine is going to be used. For instance up here the suggested is right, but going further south you could go one colder without consequence. Going one hotter down there could cause detonation, and more cold could cause crappy running. Generally though keeping with the manufacturers recommended is good. Second the heat numbers can be confusing...I believe it was Keith covered this already, but I will still re state it. The LARGER the number the COLDER the plug will be, and the SMALLER the number, the HOTTER the plug will be. I was confused by this a few years ago, and we popped a piston before we realised that we were going the wrong direction...this leads me to believe that I was not the only one, and I bet some people did not know this. Lets keep those pistons doing what they are supposed to...peace 8)

Dont buy the exhaust side pugs, waste of money in my opinion. I ridium plugs ant cheap, and the'll only really make a difference on the intake side, I beleive exhaust side is just for pollution and is only active up to 3000rpm, which means when your boosting, they do a hol lot o nothing!!

Peace

Iridium will make the most difference on the intake side of the system...also the secondary coil is only active to 4,000 rpm so it really is optional to use Iridiums on the exhaust side...but keep all plugs NGK. 8)