I've heard of water injection and I've seen it too. What is it? Whats the purpose?

http://www.snowperformance.net/

Then go to the NACA archives and search the declassified research papers there. This dates back at least to WWII and was used by both the Axis and Allies. They also give you the results of different chemical blends they tried.

Wikipedia has a reasonably good article on the subject. Water injection is practicable and offers real benefits when properly applied, but it is neither magic nor universally beneficial.

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Too many people who were born on third base actually believe they've hit a triple.

A Wikipedia article is a great starting point, I agree. Never trust it as a primary reference.

If you actually visit the NACA archive and do a casual search these papers apply (minimally); the Wikipedia article mentions only one of them (third one down):

http://naca.central.cranfield.ac.uk/rep ... e6l05a.pdf

http://naca.central.cranfield.ac.uk/rep ... rt-812.pdf

http://naca.central.cranfield.ac.uk/rep ... -e-264.pdf

http://naca.central.cranfield.ac.uk/rep ... r-e-36.pdf

http://naca.central.cranfield.ac.uk/rep ... rt-756.pdf

In "day-to-day" use, the issue with WI (Water Injection) is a matter of how you tune your car.

WI in itself, does not make more power, it allows you to safely run more compression and / or more timing advance, and avoid destructive detonation. The "hotter" tune makes the extra power and the WI system keeps the extra cylinder pressure under control.

So once you tune the engine to run WI, you need to be sure the WI system works consistently and stays working or the engine go into detonation and will likey "hurt itself".
DD

Thaks for the info, so If I'm correct WI is a way to get away with High Compression Ratio's without needing high octane fuel?

also, where do you buy the methanol for the water injection?

Many of the WI users go with common windshild washer fluid.
There is always a lot of discussion about which brand(s) are the "best" to use. ( look for the highest methanol percentage)
http://i263.photobucket.com/albums/ii14 ... isting.jpg
DD

i use -35deg walmart or canadian tire with a 50/50 mix of methyl hydrate from local biulding supplier, at 7lbs of boost , #1 12gal/hr nozzle and a 9/1 compression ratio with supreme gas and 15degs timing,seems to work. i had to time the injector nozzles with a stop watch and a measuring bottle, they flow more than the are advertised.