[Chris&aPulsar]

i have been looking at water injection for a while and i have finally got a car worthwile doing it too. a 1.8L '91 nissin pulsar, fuel injected. i was looking at the commercial units but i dont have a lazy $700 lying around. i am in my final year of an engineering degree so i was thinking of designing my own system that will use the air-flow metre to regulate the water flow.

So far i have collected this much information
? Proportional to engine load / air flow
? Only inject water at higher engine loads
? Do not use ethanol
? Mounted before the throttle valve but after the air meter

what i was wondering about, how much water do you inject into the engine? is there a way of accurately testing the optimum volume on a shoe string budjet? Any other important information that i may need to know would be useful, or comments on what i already have

i was also wondering wether the engine should be at operating temprature or close to it before the system turns on to prevent water damage to the engine and oil.

Thanks