Which spark plug would you guys use on a 2010 camaro with 515 RWHP with a a big cam? I know the stock spark plug is rated 5 for heat range so the next step would be a 6.

Should i apply 1 colder heat range for each additional 100 RWHP or 2 colder heat ranges?

Would you go 2 steps for a:
NGK BR7EF or
NGK Iridium TR7IX

Or well just 1 step ahead to a 6 heat range numbered spark plug?
NGK BR6EF or
NGK TR6IX

thanks for you comments!

 

If its n/a it wont matter. Run the coldest plug you won't foul, which is probably a 7. I like the BR7EFs, I'm running 8s now.

 

TR6s will be fine.