spark plug heat range advice

[parmas]

Originally Posted by chris-mr2

Thats what im trying to get my head round, correct me if im wrong.....

i have gone from a grade 6 plug to grade 8 (2 steps colder i belive) to dissipate heat from the plug more due to increased power and boost etc

What im trying to find out is that seeing as my plug is colder due to the water/meth do i need to be 2 grades colder, or would a grade 7 be more suitable

Specify your engine vs stock engine (if upgraded) in terms of boost / rev-limiter / engine compression / upgraded cams ?

Also what air temperature readings are you getting while water injection and what are your ambient temps ?