I have a dry shot of nitrous that I am shooting a 125hp shot right now.

I would like to up that to a 150hp shot this summer.

I presently use a NGK R5671A-7 (heat range 7)
I use this for cruising as well as the strip.

So far the plugs are reading good.

Should I go to a cooler plug with a heat range of 8 or 9?
And still use the -7 for cruising?

 

Bump?

 

that heat range would be fine. you could probably hit those plugs with alot more than that and not see any issues. once the heat mark makes its way around the bend of the strap and heads toward the threads of the plug you will need to go colder.

 

My 383 at 11:1 comp on pump gas and 150 shot used an NGK 7 heat range and its fine. I use an 8 on my turbo car at over 1000 whp. Pump gas. Should be fine

 

Thanks for your help guys!