From what I know about watercooling (from PCs) any water or Ice that you put in this loop must be distilled water because over time if you use normal water, and even distilled water, there will be a tendency to corrode the inner workings of the pump and/or the piping of the loop (SC and HE). I guess the only way you could add ice to the system is if it was only distilled ice

I would still use coolant since there are anti-corrosives in them whereas pure distilled water does not and over time the remaining crap in the loop will begin to corrode and I don't think there's going to be that much of a performance gain

I was poking around the net and saw some bike guys using Engine ICE.....anyone ever use it?

http://www.engineice.cc/