Best engine temp for horse power??

I know you're trying to get near that 13sec mark. As said earlier, warm oil and cool intake temps are the best.

Now that it's summer, if you can get a cooler/dryer day, and as long as you're oil pressure is good, i'd.......

Use thinner oil, if possible.........
Ice the intake with some Ziploc bags just before the run......
And maybe look into installing a cool can on your fuel line.....

I used to like to leave the line at no higher then 180* on the water temp.