Methanol (nitromethanol) racing fuel actually contains only half as much energy per lb. as gasoline, but it mixes with air at 4:1, where gasoline mixes with air at 16:1. That means you can dump 4 times as much into the cylinder for the same amount of air and the net result is twice as much energy from combustion.
Not sure it was nitromethanol. I’ve heard of nitro-methane, which is what top fuel drag racers run. I just ran straight methanol (that’s what the label on the barrel said, anyway). Don’t know anything about it, other than it was a pain in the ass. It absorbed moisture, too much of which would disqualify you on race day, it gummed up the carb if you didn’t clean it after race day was over, it was more expensive at that time than gasoline, and it was harder on the engines.