Here is an idea:
When you heat water, think Ocean or cup of coffee....... how long does to take to cool down? *a very LONG TIME!* that is cause it has a very high specific heat capacity.
Like George Michael and Elton John, it goes both ways.
Once you get to it you are fucked.
Water is awesome as a total loss coolant, its far better using it in the engine rather than around it 
You only need to use small amounts and you can totally change the pressure profile in the engine (run engine at 100% more power, while still not exceeding the peak pressure and temperature you had at far lower power). It is far more beneficial to use total loss cooling system and you need non of the complexity of needing to cool the water back down
(this is what I meant by extra plumbing and radiators etc etc).