Rusty, it’s certainly possible the weather contributes to the different results.
I’ve never run the dyno in the type of soup you guys are stuffing with down there in the summer.

Also, not all race fuels are created equally........ and I’d never bother trying to run c16 in a 10.75:1 motor.

But frankly I’d be absolutely shocked to lose anything even remotely close to 25hp by swapping from 93 to c12 out of a sealed can(I’d be pretty surprised to see that type of combo even lose 5hp).

That would be my suggestion for the next time you go to the dyno with something that’s at least 10:1 CR.
Pick up a factory sealed 5 gal can of c12....... and retry the test(if you’re so inclined).

I know of several people who have used several different brands of the lower grade race fuels(like VP Red for example), that got less than stellar results. Although I don’t know if those tests were done using fuel from sealed cans of not.

I can tell you this....... a lot of race fuels don’t keep well at all once the seal has been broken....... so if you’re not testing fuel from a container with a freshly opened seal....... imo you’re leaving the door open for misleading results.