I was talking to a SS engine builder the other day and he said they chill the water before pushing to the line. They try to keep the water temp below 100 degrees on the starting line (that is after the burnout). Have to use a 0 weight oil. I've never tried any tricks like that myself but I do know that if you want to make some extra power on the dyno you just crack the valve and let more cold water into the engine. Sometimes if you look at dyno sheets you'll see that people are running the engines at 120 or 130 degrees. I usually run all of my tests at 180 so I guess I'm giving up about 20 or 30 hp.