Spark plug heat range question

[Todd]

I did a quick search but didn't find a specific answer to my question. If anyone finds one please link me to it.


My question is when do you guys suggest going up, or more specifically down (colder) in heat ranges?

I have now joined the ranks of the forced induction crowd and went with a colder plug. I have always heard it is the right thing to do. But never heard specific reasoning to why one would go 1 step cooler, 2 steps cooler, etc.....

Anyone got info on that?

[RF Overlord]

Todd, dropping a heat range or two, along with lowering the thermostat to a 180° version, helps to prevent pre-ignition on motors that have had the tuning tweaked. It's generally only done if the programmer (tuner) recommends it due to characteristics of their specific tune. For instance, I know Dennis usually does recommend using 2-step cooler plugs, but other programmmers do not...

Trilogy also used to recommend 1 step cooler plugs, along with a change in gap, but I believe I read in their forum that they no longer recommend this practice. You should check with the vendor of your forced induction to be sure.