So how do you determine how much water to inject? Based on boost, rpm, fuel flow rate to the injectors?
What happens if too much water gets injected?
I still am not quite sure where the injector is installed...in the air intake pipe to the turbo?

What type of circuit would be needed to run the WI system?
One that looks at Rpm, speed, knock, engine temp??

I ask because I am looking for a project for my VLSI class. (very large scale integration). We need a project for this class to design and possibly fabricate a simple processor (of sorts).
Does anyone have any info on equations/ratios of air/fuel,rpm and such?
-Dave

 

I don't think anyone has done enough testing to come up with any equations or ratios but I would use the aquamisters jets I heard that above 50 psi it looks like a fog coming out. and I ahve heard you can put them eithter before or after the turbo.

 

Rule of thumb: You want your water injection to be putting in about 10% to 15% of the amount of fuel injected. I'm gonna be making a WI system soon using the hobbs pressure switch, fuel injectors and a fuel pump. Hopefully all will go well.

goodluck

 

Aquamist suggests as a good rule to use 10-25% water to fuel ratio. My system uses 20% with great success. water comes on at 7PSI.
here is a very scientific article where the goverment tested water injection on airplane engines back in WWII.
they were esentially trying to use water so they could run leaner or lower octane. The water allowed leaner fuel which allowed for greater flight distances on the bomber missions... real good information here


http://naca.larc.nasa.gov/reports/1943/naca-report-756/

 

Forcefed1: So your system is set up so that at 7psi you start misting and dont stop until pressure drops below 7psi? What rate do you mist water (I guess gallon per hour is the rating?)


Is it ok for the turbos to have the water sprayed before them? Can't the water cause damage to the turbine blade spinning that fast?

Thanks
-Dave

 

Aquamyst suggests injecting the water after the intercooler for enthusiast's use.

Injecting before turbo is reserved for racers.

 

I use a Spraying Systems USA air/water atomising nozzle (modified to my specs) it will completley atomize water at low pressures of 5 psi, it mixes air from the turbo with water from the tank, there is no blade errosion when using a high tech low pressure nozzle such as this.

My system costs about $500 Aus, for a Al tank, and all parts needed to complete the system.

And yes like aquamist I recomend best results are achieved when injecting before the turbo, there are no droping out issues.

 

Rice Racing, do you know what model of nozzle you have? Where do you pull pressure from? just a hose off the intercooler ducts?
-D

 

Coop
Yes my system begins at 7PSI and continues misting untill the pressure drops below 7PSI I use 2 .6mm aquamist nozzles on my eclipse. for the 7 I have 2 .8 mm aquamist nozzles. The first one comes on at 7 PSI the second stage is plumbed into a pressure switch reading the blow off valve of the second turbo and the 1st stage. This way stage 2 comes on with the second turbo and above 7 psi. at the pressre Im running the nozzles are rated for 175ML/MIN each for my setup this works out to be about 17% water/fuel. WOT

 

SUE18A, I get the pressure of the manifold pipes before the TB.

I modify the nozzle to give around 340ml/min flow @ 19 to 20 psi water/boost pressure.

 

Hi Israel (and everyone),

For those of you who will be attending the SEMA show in Las Vegas next month, Boosted Group is hosting the booth for Aquamist at this year's show. I will have my MR2 on display in the North Hall and would be happy to show you the Aquamist system and discuss what it does and how it works. I’m confident that this set-up will prove to be a powerful weapon in your guys' ongoing fight to prevent detonation. Hope to see you there.

-- DavidV

 

Pardon my ignorance, but will a water injection system help reduce intake temperatures and thus increase Hp for a car with the stock computer and no other modifications? I was considering an aftermarket intercooler, but changed my mind after seeing the price and articles about intercoolers just being heatsinks. I want more bang for my buck.

Will the stock ECU start running more advanced timing automatically with a WI system?

 

I think you are better off with an intercooler. You can achieve the same effect with an intercooler but it would be less likely to fail than a water injection system.

 

So what if I run out of water or the pump fails. Shouldn't my car just go back to running normal?

 

If you are running in a range of boost that would create more knock but the WI helps keep temps down and reducing or eliminating knock and then the WI fails you will most likely experience more knock and detination. If you tune to use a WI, and it fails, I would refill asap.

I have read that you can use the cheap windshield washer fluid (the blue stuff) because it is almost 50/50 water and isopropal (small % coloring), so it won't freeze, and you can still use it for your windshield of you like. (if you are using the same resivour (sp?) )

The only way the car would go back to running normally is if the ECU knew when the WI system was on. And then knew of you ran out of water then the WI system wasn't working and the boost and fuel and timing was adjusted correspondingly. That would be cool!

 

So you are basically saying that the stock ECU will not re-tune itself to advance the timing or increase the boost by sensing lower intake temperatures caused by a WI. The only way to benefit from WI is to tune an aftermarket ECU or boost controller. Is this true? Is there any benefit to having a WI on a stock ECU/stock boost control just because the intake air will be that much cooler???

 

Does the stock ecu have a way to read intake temps?

 

of course it does

thats what the little sensor that screws into the bottom of the UIM is for...i think 2nd runner from the firewall..

-Nic

 

Cool, I didn't know that, guess that is why I am here, to learn

 

Will anyone answer my original question?:

"So you are basically saying that the stock ECU will not re-tune itself to advance the timing or increase the boost by sensing lower intake temperatures caused by a WI. The only way to benefit from WI is to tune an aftermarket ECU or boost controller. Is this true? Is there any benefit to having a WI on a stock ECU/stock boost control just because the intake air will be that much cooler???"

 

i could be wrong, but i dont think the air temp sensor factors in to change advancing or retarding the ignition. it deals with how much fuel it puts in.

any aftermarket ECU will compensate for air temp readings....it factors into your a/f compensation numbers in the map along side your MAP (air pressure) sensor to figure out how much mass of air (oxygen) is flowing into your engine.

 

the only thing the stock ECU will do is add more fuel after seeing that the air temp is lower.

 

does anyone have a pic of where they installed the pressure switch, and how and where you are reading pressure... Just pull off one of the nipples on the UIM?

I have almost everything I think I will need to install the Wi system ( I went with Aquamist nozzles, they are the cheapest and most highly recommended)

-Dave

 

So more fuel plus colder air should equal more Hp, correct???

 

Well colder air is more dense air, so more air mass is being pushed into the engine if it, (the air), is colder. With more air you want more fuel to keep A/F ratios. More air and more fuel = more power....right? (please correct me if I am wrong)