When you inject alcohol you're injecting a fuel that is known to allow you to make more power than gasoline . It cools and it introduces more oxygen to the motor and it burns differently. Since you're injecting a fuel,you're creating a richer mixture. You'll want to adjust the mixture for optimum performance. Once you achieve optimum performance with your mixture and you then add water,you've changed your tune and you need to re-adjust. This always has been and always will be an apples to oranges comparison.
Because(as Julio has pointed out)water flashes at a higher temp ,it's going to work better in a different/hotter environment. This is another reason it is an apples to oranges comparison. However,the application where water shines(on a turbocharged engine)is when you inject it into the very hot environment of the compressor. Water flashes very well in this application. It keeps the air from being heated in the first place. Generally speaking,the Buick community refuses to accept this very old,proven tried,and true method of extracting the most power out of a forced inducted engine. We continue to heat the air first which makes the turbo work harder and run out of breath sooner. Then we cool it down after the fact. Because pre-turbo water injection cools the air as it is being compressed,which causes less of a work load on the turbo,your turbo doesn't run out of breath as soon as it would otherwise. This causes your turbo to breath like a larger/more efficient turbo.
Nothing on the planet cools like water does. If we use water for this application,we extract the most power out of the turbo charged engine with the most efficiency. If we don't do this we are leaving a lot on the table.
After we do this we can debate fuels,but nothing takes the place of this. Not even alcohol.
Please stop comparing alcohol to water
http://www.riceracing.com.au/water-injection.htm
http://wannaspeed.com/index.php?main_page=product_info&products_id=181
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