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Discussion Starter #1
Has anyone here ever used a water injection setup on their sup's or any other car for that matter? I'm hearing about significant gains in HP and in milage with water injection kits....
 

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Water injection is used on Forced induction cars (i.e. blowers or turbo's) to do a few things. What it does it spray a very fine mist of water (or water alcohol mixture) into the intake charge prior to it entering the combustion chamber. The two main effects this has is that it increases the effective octaine raiting of the fuel (atomized water and/or alcohol will burn, but relatively at a very slow, controlled rate) and decreasing the intake charge temperature (which will also make the fuel charge less likely to detonate under high compression conditions). I know of a few Grand National/Regal T-type guys who run 20 pounds of boost with no Intercooler and a water injection system, and it works well for them. There is a point of diminishing returns with these systems, and there are dangers of using them as well, but a properly set up and used system will work wonders.

Using a water injection system will not give you more Horsepower by itself, nor will it increase your gas mileage, as thats not its intention nor design.
 

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Who told you water will burn? I assure you this is not the case! What it does is flash into steam, thus absorbing latent heat from its surroundings.

The point of water injection is to reduce combustion chamber temperatures, which allows you to run more boost/compression/ignition advance. It does not increase the octane of the fuel, but it has a similar effect. If you tune your engine accordingly you can see worthwhile gains, but I doubt it would be worth it on a NA 5M-GE unless it was heavily modified.

A nice side-effect of water injection is it keeps you pistons and combustion chambers squeaky-clean; it effectively steam-cleans the engine's internals every time you use it! :)
 

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Norbie said:
Who told you water will burn? I assure you this is not the case! What it does is flash into steam, thus absorbing latent heat from its surroundings.

The point of water injection is to reduce combustion chamber temperatures, which allows you to run more boost/compression/ignition advance. It does not increase the octane of the fuel, but it has a similar effect. If you tune your engine accordingly you can see worthwhile gains, but I doubt it would be worth it on a NA 5M-GE unless it was heavily modified.

A nice side-effect of water injection is it keeps you pistons and combustion chambers squeaky-clean; it effectively steam-cleans the engine's internals every time you use it! :)
If set up properly, a portion of the water WILL burn. The reason being is that water is made up of Hydrogen and oxygen (which I know you already know), and both of these burn VERY well (again, as I am sure you know.) Certain water injection systems are set up in such a way that some of the water or water alcohol is sprayed so fine that it is indeed possible to burn the mix... tho this is more on the Alcohol systems... guess I shoulda been more specific on that.

As for the Octaine... the water mixed into the fuel and air charge makes the charge less prone to detonation as water controls the burn rate of the fuel and (as you said) lowers the intake charge temp... god damit.. I know this isn't coming out clear... let me repost later tonight before I take my pain killers again.
 

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Splitting water into its component elements requires very high temperatures, like 1000 degrees C and above. I seriously doubt you'd see that sort of temperature inside your engine; if you did, it would melt!

I might add the the energy required to split water is more than the energy gained by re-combining H2 and O2 (this is one of the fundamental laws of thermodynamics), so there wouldn't be any point doing this anyway.
 

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>steps out of the drug induced haze for a few minutes and begins to wonder how to pull is foot out of his mouth<

Ok..I think what I was trying to get at was the Alcohol would burn in the mix... or something to that effect.

How about I just shut the hell up for now and enjoy my pain killers? :oops:

::beats his head into the wall for refuting thermal dynamic laws...::
 

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I Know of someone who ran water injection on his 7M and stock CT26, he was able to make 18PSI of boost with no detonation (he also had a fuel cut deffensor).

Carl
 

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Discussion Starter #8
What about on NA engines, I have been talkeing to a guy that has installed a water injection system on a 4cyl toyota engine, he is claiming that he is getting a 10% increase in mpg while at cruising speeds on the freeway (being a commuter this would help me A LOT) Water would cool the air thus making it denser correct?
 

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TOYMAN321 said:
Has anyone here ever used a water injection setup on their sup's or any other car for that matter? I'm hearing about significant gains in HP and in milage with water injection kits....
I have heard the same claims, since 1980, but still 20+ years later, nothing substancial about it, other than what has already been listed above. From what I remember from an article that I read in 1979/1980 time frame, the water injection was to help cool the piston down to keep the fuel mixture from preigniting (ping). I was looking into the water/alcohol mixture, because the alcohol in it was suppose to help with the octane rating. I worried about things like, where does the water (which doesn't burn (but I could be wrong :shock: )) go after it leaves the cylinder? Would it rust my exhaust, headers etc? Stupid idea I know, but I could never get a clear answer on that. Some of the B52's use water injection to help them get off the ground, so there must be something to it.
 

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Discussion Starter #10
From what I have read and heard water injection should not be used on startup and near shutdown of the engine. The engine needs to be warm enough to vaporize instantly the water otherwise you run the risk of getting water in your oil, letting the engine run for a few minutes before shutdown w/o water lets the pipes dry out completely. Keep in mind in most applications very little water is used (as far as I have heard) in a NA or even a forced induction car (i.e. 1 liter should get you though a full tank of gas)
 

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Like the old saying goes, if it's too good to be true, it probably is...
That being said, if the claims were true, we would have seen something like this installed in vehicles from the manufacturer already. In fact, with the way folks were in the early '80's, they would've experimented with that theory a lot!
I do however remember a CarCraft magazine article saying the best way to clean your engine was to squirt a little bit of water down your carb every now and then (on a hot engine of course!) and it would clean the carbon and oil deposits in both the carb and valve faces, and as Norbie stated, the piston heads too! They did forget to mention not doing this on a Chrysler 400cid w/the 4bbl carb that was made outta PLASTIC!!! A new carb that same day, the car was running once again...


:mad:
 

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One of the normal by-products of combustion is water, in fact your exhaust is 99% C02 and H20, so you don't need to worry about water injection rusting your engine or exhaust any more than usual! As mentioned above though, it's probably not a bad idea to run the engine without water for a minute or so before shutting it down.
 

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well, since i plan on running 20+psi when i build the new 7m, i was thinking of using this. however, i would set it up with a hobbs switch to kick it on prolly ~10-14psi. that way it wont be on all the time and since ill have my turbo timer set up by then it will always idle a few mins before shut down and the water wil be off so it shouldnt be a problem. now, the issue with that will be i will have to find a sensor to install on the water reservoir so that when it gets low it can turn on a light so i dont go boosting without any water and melt something. i could easily mount the warning light on the dash in plain veiw.
william
 

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oh, and if you spray too much water you can create a condition known as hydro lock, which is where your engine will lock up as water cant be compressed. depending on the rpm this happens, it may only stop the engine cold. however, i have seen rods get bent, and even break and put holes in the block. so if you use this, be very careful. it has many benifits, but can be very harmful if its not used correctly.
william
 

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One key factor here is to remember that alcohol absorbs water, creating a combined mixture of alcohol and water. The key is to maintain the proper ratio of alcohol to water in order to keep the mixture combined. Alcohol by itself is a fairly clean burning, stable, combustible fuel that is also more resistant to pre-ignition and detonation from high cylinder pressures than gasoline vapor, thus allowing for more spark advance, etc., and some increase in power and efficiency. Alcohol also has the inherent ability to absorb heat, which can be good or bad since the whole idea is to rid the intake charge of excess heat altogether. By adding water to the alcohol, the water portion effectively helps keep the temp. of the absorbed heat down to a minimum, thus lowering the charge temp. more effectively. OTOH, straight Methanol is sometimes injected directly into the outlet stream of a turbo to absorb the pressurized charge heat that would otherwise be absorbed by an intercooler. So...why don't we just run our engines on straight Methanol?? We could produce more power this way, but alcohol isn't readily available (not yet anyway), plus you have to induce approx. twice as much alcohol by volume to achieve the same energy output as that of gasoline. :? Water can be seperated into it's two parts H2 and 0 by using electrolysis or a device known as an electroliser.
 

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Water injection is especially useful in areas where the ambient air temps. are high and the relative humidity is low (hot, dry air). Another trick is to chill the water before it gets injected so that the water can absorb even more charge heat before it flashes into vapor. A chilled water/alcohol mix can work even better. :)
 

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you could also, you know... do water sprayers onto an intercooler, alo the new mitsu evo and scooby sti.
 

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yes, you could spray the i/c with water as well, however i personally am going to set up a co2 system to chill the i/c.
william
 

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williamb82 said:
oh, and if you spray too much water you can create a condition known as hydro lock, which is where your engine will lock up as water cant be compressed.
I have yet to see a water injection setup capable of supplying anywhere near enough water for this to happen. A 2.8 litre engine consumes a LOT of air (93 litres per second at 5000rpm assuming 80% VE), so you'd pretty much have to pour water into the engine from a bucket before it would lock! This is a far cry from the small fogger nozzles used with water injection...
 

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I think the key here is to remember that there is space above the piston crown in the combustion chamber at TDC. Any volume of water induced that doesn't get vaporized and exceeds the volume of the quench area could cause hydraulic lock since water in liquid form can't be compressed.
 
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