What is water injection?

Water injection is a venerable technique for achieving all kinds of good things in the engine by lowering the combustion temperatures.  This has a cooling effect on the intake air charge, which increases power and reduces the possibility of knock.  This has the same effect as adding extra fuel to the mixture without sacrificing fuel economy.  Additionally, less fuel (a leaner mixture) in itself reduces the possibility of detonation.  A nice side effect is that the water tends to keep the engine cleaner, whereas extra fuel can actually leave more carbon deposits behind.

The theory is simple: water is atomized into the intake air stream, and is included in the air/fuel mixture burned in the cylinders.  Since the cooling effect is not typically needed in everyday driving, the injection system is normally activated by a pressure switch that activates at a preset boost level.  The injection point is either just before the throttle butterfly or before the turbocharger, depending on the exact setup. The water is sometimes mixed with alcohol or other fluids.

Downsides to water injection include having to keep water in the tank, and the possibility that a malfunctioning valve might put too much water into the engine, causing serious damage.  However, the technique has been around since the 1940s and the risks are arguably no more serious than relying on an over-rich fuel mixture to provide the required cooling effect.

Unfortunately, nobody makes a DSM-specific water injection system; several vendors offer generic versions.  Speculation on the subject has been wide and varied over the years, but few people have actually installed such a kit on their cars.  Many people regard it as old technology, while others class it with nitrous injection as an 'unfair' system.  This lack of practical knowledge and a proper bolt-on kit for DSMs has kept the technique from wide application.

Water injection has recently drawn more attention in the Talon Digest, partly because a group buy for the Spearco WI kit has drawn all the WI users out of the woodwork. There is also a little-known DSM Water Injection Home Page for interested parties, as well as the DSM Water Injection Group from Yahoo! Groups. You can also peruse issues of the Talon Digest from January to mid-February 1999 for DSM-specific information.

Related to, but separate from, the water injection systems is the intercooler sprayer, which sprays water or other coolant directly on the intercooler to help it do it's job.  This system provides only minor benefits but is simple, cheap and failsafe, and may be rigged with a pressure switch to activate it during high boost.

Here are some questions answered by Devil's Own Injection Onwer / Operator

Q: How hard is methanol on parts in the car Plastics in the car and in the system:
Methanol in general is harder on alloys than it is on plastics. Most plastics in a car are a nylon 11 /12 or Polyethylene and are A-Excellent with Methyl Alcohol And generaly most all makers use poly or nylon for the transfer hose for this kits. . 

Rubbers in the car and in the system:
Only source of rubber in the car these systems should come in contact with is your hard pipe couplers and they are made from Silicone and its considered A-Excellent with Methyl Alcohol. Now some manufactures sell alcohol injection pumps with viton seals that are C-Fair .  So make sure the pumps have EPDM seals. If they don't say then its probley viton, which you don't want. 

Alloys in the car and in the system:
Aluminum for example is considered meth compatible by some and not by others. When it boils down to it its the grade of aluminum that causes this. Most aluminum go kart tanks that are not anodized will not fair well with constant contact with methanol. Aluminum intakes for example, since they are not under constant contact and they are a lot more substantial would be considered compatible. All of your Stainless Steels are grade A 
Brass, while considered compatible with both water and meth we have found for it to create a coating on the inside of these systems, This is the main reason we use Nickle plating on all the fittings.