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Discussion Starter #1
I know alot of you guys use the aquamist setups, but has anybody gone with and alcohol setup? The benefit to alcohol being that it has more of an intercooling affect and adds octane at the same time. Simple kits can be had for less than 500US, and would provide a nice measure of protection.
 

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Originally posted by Samba_GS-R:
[qb]I know alot of you guys use the aquamist setups, but has anybody gone with and alcohol setup? The benefit to alcohol being that it has more of an intercooling affect and adds octane at the same time. Simple kits can be had for less than 500US, and would provide a nice measure of protection. [/qb][/b]
Firstly, water cools better than alcohol.

Secondly, if you're going to add octane it's best done by putting it in your fuel, rather than in your air mixture.

The usual benefits of water injection are being able to reduce the number of "non-burning" elements in your combustion.

Any time you engine goes richer than about 14:1 any extra fuel in the cyllinder simply doesn't burn. It does slow the combustion process two ways however.

One being it cools the gasses slowing the initial flame kernel down.

Two being it causes a baffle against the flame front as it travels, slowing it down.

Slowing combustion down is bad. But because the alternative is usually knock, it is tolerated to squeeze some extra hp out of your engine. (or as a safety margin)

Because only a 12-13:1 a/f ratio is necessary to get proper combustion even under high boost (assuming there is no knock) any extra fuel is used simply to cool the system down and prevent detonation.

Alcohol is a better air coolant than gasoline ... but water is far better still.

Water is not only able to cool more per pound injected, but also it actually has a better "chemical" effect.

When you inject alcohol or excess fuel you leave unburnt hydrocarbons in the cyllinder as the flame front moves away from the spark plug.

These un-burnt hydrocarbons slow down the oxidation of CO ---> CO2 ... which is one of the power producing reactings during combustion.

Water does not inhibit this process, and so the flame front not only propogates faster (which allows you to get the same power on less ignition timing) but water also makes for a more complete burn and lowers both your CO and NOx emmissions if tuned properly ...

However ...

It's extraordinarily difficult to tune for water injection. It's essentially like completely re-engineering your fueling system if it is done properly, and this is why most auto makers and tuners do not employ it.

It can be used to give an "added margin for safety" at any power level fairly easily though.

For instance, you could install a very simple aquamist system that you only activate on hot days when it's necessary. This would be the most ideal solution.

At any rate, if you want more octane go read the thread on fuel quality ...

If you want cooler charge air (which does the same thing) then go look up aquamist water injection.

If you REALLY want to know more about water injection though ... go here:

http://www.turboice.net/

There is a LOT of good information. A small portion of which I even contributed myself , though I've yet to even buy a water inejection system.


It's a very useful site. Have fun!


Dubbya~
 

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Discussion Starter #3
I was more refering to the standard denatured alcohol(or methanol)/water mixture injection kits commomly used on turbo/SC cars in the US. The mixes are mostly water, combined with alochol or methanol mixture. Thus providing the air cooling affect when the alcohol/methanol evaporates, it absorbs the heat in the air, cooling the intake charge. The remaining water helps control the detonation factor. I think I may look into a system like this.
 

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Most of the time they only use alcohol to lower the freezing point. This is because otherwise the water in the tank can freeze over-night, and you can't put anti-freeze in your water injection system for obvious reasons.

Aquamist does not reccomend alcohol in most applications because it is corrosive to the rubber seals in the water pumps.

And remember, water cools better than alcohol per pound, and is more dense, making it cool better per gallon.

Also remember what I said earlier about un-burnt hydrocarbons. You'll likely see more power, and cleaner exhaust, with just water ... if tuned properly. (Which is the hard part anyway.)

But if you are going to use a mixture, I would suggest 20% or less methanol, and I would suggest replacing the pump seals at least once a year or more, just in case.

I still think you'd be better off with just water, and toluene in the gas tank for track days. But it's up to you.

Dubbya~
 
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