I had about a 10 deg drop also. I still used the fan during a run. It can still get hot on E85 just takes a little longer and will cool quicker. I ran E85 for about 5 years and it worked well.

Alcohol is in my opinion the best bracket racing fuel there is. You will be able to double up on any day without any issues getting hot. the only thing that will get hot is the trans if you don't have a good cooling system for it.
Only used the fan to control the temp before a run and shut it off during a pass.

Al