I too have played with that calculator. And for me the best thing about it is getting a handle on how the different components of intake, IC, turbo, AFR, and WI cooperate to make hp. I agree with hotrod the model used in the calculator is too simple for our stuff and does not account for the saturation limit of dissolved water. The 100% "humidity" is an upper bound of WI, but both ambient air saturation and temperature affect this bound. Ideally we'd like to have a system that never reached the 100% saturation limit at any point in the air path (the bound is going to change, being highest just after compression, and probably the lowest while inside the intercooler". We dont' want precipitation at any point (e.g rain fall, fog formation), that will lead to water build up and all sort of "unintended" effects.
One calculation that I think would be worth performing is to figure the amount of heat produced at the highest operating RPM of your turbocharger and then calculate using the heat of evaporation for water +/- % methanol the amount of fluid needed to bring the compressor to isothermal compression. Assume that you are getting "explosive evaporation" as hotrod suggested.
Instead of using a compressor map with "predicted efficiencies" and a PR, if one were to actually measure pressure and temperature pre and post turbo, the energy going into heat should fall out of the ideal gas law. Now we divide this energy loss by the energy gain of evaporation, and we'll get a percentage of water/methanol injection. It's a ball park ideal figure, but it could be informative. Anyone have thermocouples in said places to take the measurements, and a boost gauge?
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