I am running about 12 to 1 and was wondering whether to go with a hotter or colder plug? I broke the motor in on the stock heat range plugs but I am am going to up upgrading as soon as I get exhaust on the car. So, which is better hotter or colder for high cr and why? I have heard it both ways from people that should know what they are talking about.

 

No one knows for sure? Any ideas?

 

Hotter = possible detonation
Cooler = increase deposits and or fouling

 

I ran one colder heat range on my 12:1 396ci motor with no problems at all.
Jason

 

try cooler out and see, you may not need to change at all from stock. youll just need to test it out and find out what works.