whats the deal with colder spark plugs

[acannell]

okay whats the trade off with hotter/colder spark plugs? (for our turbo engines)

if colder ones are better on turbos, why didnt chrysler just spec colder ones to begin with?

there is no big cost difference right?

whats the deal.

what are the PROS

what are the CONS

[acannell]

check this out:

NGK heat range info

SO

lets say I turn the boost up to 15 psi on my 2.5 turbo, and then I add a HUGE intercooler and +40's, etc... so that there is enough fuel.

now if I observe my EGT's after the mods, and they are within the range I like (whatever that range might be), then I wouldnt want a colder plug right?

[DblTrbl]

colder plug just means that it will disspate heat in the tip faster.

So if you're running lots of boost, the combustion chamber gets hot. If the plugs tip gets too hot, it can cause detonation, so colder is safer for high (higher than stock) boost.

Under normal driving, cold plug will foul, so thats why it's not a factory item. Some foreign cars run hotter (for better gas mileage) and they use colder plugs to make up for it.

I don't consider 15psi high, many TDers run 25-30psi, so cold plug is important. Fouling on the way to and from races is the norm.