Isopropyl Alcohol

Regular denatured alcohol will do better then isopropyl (which is about 30% water to begin with). Whatever you do, make sure you use ethanol NOT methanol. Methanol will corrode the zinc components and harden older non-viton rubber components in the fuel system. A gallon or two of E85 will pull the water out, and clean up any varnish pretty well.

Adding alcohol will not increase combustion chamber temps. It can't. There is far less caloric energy in a gallon of alcohol than a gallon of gasoline. It simply has less heat in it, and burns far cooler. Most of your cheaper "octane boosters" are alcohol based, and work by lowering chamber temperatures.

Have you noticed now that we are forced to buy 10% ethanol gas in most parts of the country, water in gas is less of an issue?