Exhaust Gas
 

Exhaust Gas Recirculation

Takes some of the unburnt fuel and runs it back through the intake manifold for cleaner emissions and better gas mileage.

And how does it provide
 

And how does it provide "cleaner emissions" ?

Water in gas = Jello in Fuel line
 

Water reacts with Ethanol in gas to make a gel that will completely clog a fuel filter. This can happen casually from condensation, and any dry gas will start to disolve the gel. Water was added to Turbojets in the 50s. The idea was that at higher altitudes the water added density or an expandable substance, so there was more expansion inside the cylinder, when the mixture heated up. Think, if a liter(1 gram) of air will expand from to fill a 10 liter space when it's temperature is raised 1000f, and adding water(1gram) increases this to 20 liters, why not add water? I have a feeling that they encountered a corrosion problem with this.
I contacted a person at HESS and asked about a good starting place for info on gasoline additives and they suggested epa.gov. Here is a link with Reformulated Gasoline info. https://www.epa.gov/otaq/rfg.htm#Fact

Re: And how does it provide
 

Burning a bunch of crap that otherwise would be shot the heck out the tail pipe or not converted totally by the cat. Doesn't let as much stuff slip by, :-)

Re: And how does it provide
 

Much of the exhaust gases are burnt so they are inert.

Recirculated "burnt" gases to intake displaces some "fresh air" so that less fuel is injected by keeping the stoichometric ratio of 14.7:1.
And also this process is actually designed to "cool" the combustion chamber in order to prevent harmful NOx gases that occur under very high temperatures.
EGR works under part load conditions and somehow it is like converting a 2.0 liter engine to 1.6 when power is not needed at a particular rpm.

Highly elegant, known and used technology for:
- Keeping not to occur NOx gases.
- Fuel economy.
- Cooling the combustion chamber.


EGR does not work at idle and at WOT/maximum throttle situations.
So: Water injection should start when EGR is closed. which it is used in high performance cars.

However i am too planning to build a water injection system also to see how will it effect performance and fuel economy.

Did you guys have experience on making water injection by using "ultrasonic humidifiers" ?

Ultrasonic Humidifiers
 

Cool idea, and the only place that I've encountered them is in VERY large air conditioning systems for High Rise buildings, and in computer room HVAC systems. Evidently they are very energy efficient, very effective, and the amount of wate that is put into solution in the air, can be precisely controled.
Also if memory serves, they don't look like much more than the end of a pipe with a flang, so they would probably fit nicely through the plastic part of an air intake manifold. If the water was preheated to just below boiling, this would help solve the question of increasing the temperature of the intake air. Also it would help stop it from freezing in the winter. How do you drain it overnight, so that the water line doesn't freeze?

Definitely on winter some
 

Definitely on winter some alcohol must be added in order to lower the freezing point of water.