when are you supposed to run a colder plug? i hear your supposed to run them when you run high boost and/or racegas.

is this true?

 

Generally, as combustion chamber pressure increases the higher risk of detonation and pre-ignition becomes prevalent. In theory you want to run a plug that is as cold as possible without fouling out within a reasonable service interval. This decision is significantly influenced by your driving style. I.E. your car makes 367hp and 363 tq, but if you daily drive it the majority of the time you will be cruise and/or out of boost. In that situation you probably could stick to stock. If you car lives at the track on the other hand it might be a good idea to start researching what part number is the next step cooler...

 

"An easy rule of thumb is for every 75-100 horsepower you add, use one range colder plug."
I learned this back in my DSM days.
http://www.machv.com/plugselforhi.html

 

if u running nuff timimg, and high boost level and u are not using any water or meth to increase the octane level u want a colder plug.

 

For example if you run the Iridium NGK 7 series (BPR7EIX), one step colder would be BPR8EIX

 

This is correct for an Evo VIII. Since the OP has a IX though the correct 1 step colder spark plug would be the Denso IKH24. I installed these Denso plugs in my IX a few thousand miles ago when I installed a SpoolinUp COP kit and have nothing but good things to say. I'm generally a fan of NGK plugs, but they don't make a cost effective 1 step colder than stock plug for the IX's so I think these Densos are the next best thing.

 

my car is making more power then whats in my sig, so dont go off that

i guess ill ask cbrd when i go to get tuned soon

 

Mind posting your mods and power? I have sigs disabled.

 

well the car is being built now, parts keep changing up so i cant really say. im looking to be over 500whp tho

 

Go a step colder.

 

good info, step colder i go

 

Speaking with AMS, they had mentioned no need to go one step colder until making much more power than I am now. Something like 600hp+ is when they said they would go one step colder.

Right now, I'm on the stock plugs and have some knock. I'm running the stock turbo at 25psi, but I need a re-tune. I'll test the one step colder if the re-tune doesn't work out

 

we run stock heat range IR's even on our TA car making well over 500whp on our dyno,

and we never run coppers,

but you will hear different opinions...

cb