ALFAGTV6.COM

[Zamani]

You watched too much Steve Irwin.

[Mezevenf]

Damn, I didnt even understand that.

[GTV6GPTT]

some one translate for me when your ready to?
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Wesley Loves Goon!

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[Mats]

However there are some real downsides and it suprises me that nobody here has really touched on them. The biggest problem when using it with a positive displacement blower or a Turbo is the issue of increasing demand as RPM rises. Most of the kits out there don't address this at all. Some do but they are very expensive.

Bingo

Here is the problem. In order to bring temps down near ambient the system must inject enough water to bring the air up near 100% humidity. Of course going over that would result in having water form in the intake system so lets shoot for a safer 80% and accept temps close but not quite down to ambient. Now most systems are set to turn on at a certain boost level and spray in a fixed amount of water, lets call that amount X. Now lets say the motor gets enough boost to need the system as low as 2000 RPM (quite realistic with properly sized turbos, or a good Roots setup). If quanity X is enough to bring temps down near ambient at 2000 RPM, it will only be about 1/3 enough at 6000 RPM. So you won't get much cooling at higher RPM where you are looking to make power. If you set it up the other way, where it injects enough water to cool the air at 6000 RPM then water will form in the intake system at lower revs quenching combustion and causing a loss of power or worse.

Now, I haven't studied thermodynamics for a while but the whole point of water injection is to use the fact that water needs a shitload of energy to jump from liquid to vapour, right? Even if you spray (spray, not pour) serious amounts of water into the chamber it will likely vapourize when the pressure rise brings the temp up in the cylinder, yes/no?
Naturally to use it efficiently we need to be able to map it just like fuel but I think the hydraulic lock problem is quite a small problems as you would have to dump huge amounts of water in there for it to happen.

Some companies try to address this with dual or triple stage systems, but those really on help centrifugal superchargers. These "multi stage" setups trigger additional flow when they see an increase in boost. If your car makes 1 pound of boost at 2000 rpm, 3 pounds at 3000 and 9 pounds at 6000 a triple stage, boost activated system could be for you. Set each stage up for the known boost levels/engine speeds/airflow amounts and the quanity will be close to correct across the board. However Roots blowers makes a pretty flat boost curve, and a Turbo is about perfectly flat once it come on speed.

What we need is a system that measures air flow and temperature calculates and injects the correct amount of water throughout the RPM range. There are systems that do that using a G.M. mass air flow sensor, so perhaps those could be adapted.

I don't think I would be too worried about failure of the system causing engine destruction. You can build safeguards into it. With forced induction everything is more critical, you could also ask, What if my EMS malfunctions and destroys my engine, what if my wastegate fails and overboosts my motor. Even with Good old reliable L-Jet and super conservative settings there are plenty of failure mods that could destroy a forced induction motor. For example a coolant temp sensor failure or AFM failure could do it.

If you want to use water injection then do it! It will help, but unless you are going with some sort of speed/density based system you won't get the tremendous cooling that the makes talk about on thier record breaking cars and would be better off with a good intercooler. Then again, a basic water/meth system would be better then nothing!

I concur.

Saab had a factory option on the 99 Turbo, water injection. Alfa had it mounted as a standard feature on the 155 Q4.

Me, I prefer the good old air-air IC, if you're not down to ambient + 20-30 degrees you're doing it wrong.
Then again I hate weight and power-robbers.

[Greg Gordon]

Mat's this is a small point but I didn't say anything about hydrolock. However since you brought it up, hydrolock is a possibiliy with the right combination of problems and it has destroyed numerous water injected engines. In most cases it's not a factor.

Overall it sounds like we agree 100% on the problems facing someone wanting to set up a good water/meth system.

A good air to air intercooler can be very effective and in some cases it's the thing to use, in some it's not. You are not alone in your love for Air to Air systems. Corkey Bell in his book on supercharging favors these as well.

[zambon]

Hmm, sounds like you guys didnt follow the link that I posted.
http://www.coolingmist.com/detailmain.a ... controller
This controller uses a map sensor to put out variable ammounts of water/meth/alc.
It has the capacity to be manually programed on with a computer. Just like stand alone fuel injection computers, for $200. Seems like an interesting option to me. Also, rumor has it that megasquirt will have built in water injection control before long.

About the hastle of mixing chemicals, I agree, it could be a pain. I had planned to use twin tanks, one for water and one for alchohol or methanol. That would get me off the hook of mixing things. The bad thing about it is that it could be dangerous to have a tank of a flamable liquid in the trunk...
Both tanks would go in the trunk, along with the water injection pump. Some added weight, but it would be about equal to the savings from removing the spare, I would guess.

[Greg Gordon]

Zanbon, Sorry I missed that link. That device does appear to fully solve the quanity vs RPM issue. Of course it also drives up cost. Figure $250 for the basic kit, $200 for the controller, $2 every tank of gas for a bottle of washer fluid (use a type that contains Methanol) and you are getting pretty close to the price of a liquid to air intercooler.

That said, I still think water/meth is a good way to go for some of us. I am using it to bump the power up of my GTV6 a whole bunch right now, along with various other mods many won't agree with. I think the best place to mount the tank and pump is in the area forward of the front wheel. It's cool there and won't require a ton of wiring and hose to hook it up. However I have not quite worked out how I am going to fill the tank without drilling a hole in the car.

[zambon]

I plan to move the battery to the trunk, so wiring the pump there wouldnt be too bad. The price is very significant, I agree. Unfortunately, at this point price is an abstract issue for me because I am currently so poor that I can barely afford to buy a tank of gas. I am planning things for the longer term.
I hope to use both a water to air intercooler and water injection in the end, so it isnt a question of which is better in my case.

As far as extra running costs go, I have heard of people happily running 100% water in street vehicles.

[Greg Gordon]

100% straight water will do a great job for cooling, but they say Methanol helps raise the effective octance of the fuel and further supresses knock. I will know soon enough.