There is some interesting ideas within this thread. Its important to note about water/methanol injection that methonal is different fromm ethanol, (everclear). you probably already know this. another is the 150 psi pumps used to properly atomize the methanol. 50/50 is the best mix, the U.S. and Nazis both figured it out for fiter jets in WWII. The water cools the combustion chamber, allowing to make more power. for better MPG you need to lean the fuel. The best part is it can decrease nitrogen oxide emissions.
A very interesting thing i found was this ...
"Many military aircraft engines of the 1940s utilized a pressure carburetor, a type of fuel metering system similar to a throttle body injection system. In a water-injected engine, the pressure carburetor features a mechanical derichment valve which makes the system nearly automatic. When the pilot turns on the water injection pump, water pressure moves the derichment valve to restrict fuel flow to lean the mixture while at the same time mixing the water/methanol fluid in to the system. When the system runs out of fluid the derichment valve shuts and cuts off the water injection system, while enrichening the fuel mixture to provide a cooling quench to prevent sudden detonation."
http://en.wikipedia.org/wiki/Water_injection_(engines)