[C25A1guy]

Water/Meth injections work, but for a street application n/a motor, it would do little to nothing, and might even possibly harm your engine. For n/a application, it would work best on super high compression ratios (I'm talking 14:1 and higher) to supplement use of whatever petroleum based fuel you may be using.

First, lets take a quick look at the chemical components that make this combination up. Water is of course H2O or H-O-H. Methanol is CH3OH or H-C-H-H-O-H (forgive me, my chemistry is a little rusty, so chem. bond chain may not be completely accurate). Methanol has an octane rating of around 105 or 110 if I remember correctly. While water does very little to nothing in terms of adding octane, what it does to and 1. act as a carrier agent, 2. act in atomization, 3. dilution agent (as 100% methanol is EXTREMELY corrosive) and 4. a cooling agent or vaporizer.

Now going on into general application. Now when the mixture goes into your combustion chamber and gets ignited, several things happen because of this mixture in supplement to the fuel you're using already. First, with the methanol, as I said, as an octane rating of around 105 or 110 (this is using M+T/2 rating, not RON), so it helps to prevent detonation. The water, when in the combustion chamber as the cylinder hits the power stroke vaporizes into a gas. We all know from high school chemistry or physics (hell if I remember which class) that when water evaporates, its an effect of cooling, so, not only will it cool your EGT's, but as its atomized into the intake stream, it will also cool your intake charge, making it much more oxygen dense.

As far as how to tune with it, basically you will need 2 tunes on something like K-pro or EMS. I have some experience with doing this on the EMS system on a supercharged NSX. You'll want to first make your tune without the water/meth to get your base map. Once you have that, you will want to pull up your nitrous table and use that as your fuel + water/meth tune. You can have it automatically switch maps using the armed trigger on the water/meth injection to also act as a switch on the ecu to change maps as well.