This is a great link:
http://www.rbracing-rsr.com/waterinjection.html
And here are some interesting facts you probably didnt already know regarding Water/Alcohol Injection...
1. Maximum Torque occurs at a 13.2:1 Air Fuel Ratio.
2. Transitional Fueling and Maximum Boost Air Fuel Ratios are about 12.5:1.
3. Water Injection is most efficient with a 50/50 water alcohol mixture.
4. Methanol, as an additive, is not a practical choice as it is prone to pre-ignition, is not safe to handle and is not readily available.
5. Denatured (ethanol) alcohol, typically 95%, is cheap and is available in paint, hardware, and Home Depot type stores in gallon containers for about $10.00. Isopropyl alcohol can be used but it is often 30% or more water by content.
6. Water Injection allows ignition timing to be more aggressive or closer to stock. In other words boost does not automatically mean retard your timing.
7. Excessive amounts of ignition retard will cause a loss of power and overheating.
8. Water to Fuel ratios should be based on weight and not volume.
9 . Water weighs 8.33 lb per gallon.
10. Alcohol weighs 6.63 lb per gallon.
11. Air weighs .080645 lb per cubic foot. It takes about 150 cubic feet of air per 100 horsepower. It takes about 12 lb of air per 100 horsepower.
12. Water or Water / Alcohol to Fuel Ratios are between 12.5% to 25%. This means Air to Fluid Ratios are between 11.1:1 and 10.0:1 with water injection.
13. Maximum water delivery should be in higher load low to mid rpm ranges tapering somewhat at peak rpms where load is less.
14. Atomization of the water mixture is directly related to it effectiveness. Finer droplets cool the inlet charge better and with less mass they navigate the inlet plenum easier for more equal water distribution.
15. Don’t flow water through an intercooler.
16. Atomized water, just like fuel , does not like to make turns thus making accurate distribution something to think about. This is why port fuel injection is the norm. Water is a fluid just like your fuel. Multiple nozzes, equally spaced in the plenum, although it complicates things, is a superior design.
17. The introduction of water will allow higher boost pressures to be run without detonation. Higher pressures will increase torque. It’s always about torque.
18. Racing high octane gasoline should be used for all forms of competition and for higher than normal boost levels. Water injection as well as charge cooling should be used with racing gas. 91/92 Octane pump gas simply will not cut it.
19. Fuel Injectors operate in the 1 Millisecond range and are not capable of long term usage for H20 as they will corrode or rust shut in a very short period of time. Unless a solenoid can open as fast as a fuel injector it should not be used to "pulse" water injection events.
20. Varying voltage to water injection pumps or using similar schemes is a recipe for disaster. You have to eliminate the variables, not increase them.
21. Fuel Injection pumps cannot be used for water injection. Water is conductive. Gasoline is not. Water will corrode an efi pump shut in a very short period of time.
22. Water injection has a cooling effect on the engine head, valves, and cylinder. Exhaust temperatures (EGT) are largely unaffected at recommended water / fuel ratios.
23. The cooling of potential hot spots in the combustion chamber defeats pre-ignition, the most destructive form of uncontrolled or unplanned combustion.
24. Higher static compression ratios will require a higher percentage of water or water / alcohol.
25. No, water does not burn. We are not combusting the hydrogen in the H2O.
26. At around 13.2:1 or fuel air ratios of .75, EGT’s will peak.
27. Ferrari suspended water in their fuel during their 1980’s Formula1 period. We don’t recommend that you try this...although Acetone will mix with water.