In Defense of Water Injection
 

So I was bothered by a recent thread where it was claimed that anything besides 100% meth injection was the way to go. There seems to be a lot of misunderstanding and empty claims as to why, and some poor guy with a simple question was being fed all of it. I don't have the time to give a full report, but I found a guy who says everything I would have tried to say, except better. Besides that, his combustion chemistry is much better than mine. Even though it is a diesel forum, it applies to the otto cycle as well. I would encourage you to take a look at his explanation here: http://www.cumminsforum.com/forum/89...injection.html

Also, if you get a chance you can read Pounder's Marine Diesel Engines and Gas Turbines, by Doug Woodward. It talks about water injection using various methods, but it really only talks about the emissions benefits and NOx reduction, since there isn't really a reason to hot rod a commercial ship. It does support some of what DanC says in that other forum. It also specifically states that power isn't adversely affected and fuel consumption remain the same, but they're not trying to make more power with it anyways. Could they? Yes. And I bet you could remove your catalytic converters on your car to free up some more power while you're using the emissions benefits to pass the sniffer if done right.

So, don't believe the marketing and peer pressure used to convince you to buy a certain product. Run your meth or your water injection as is necessary for YOUR needs and goals, and then choose the system that gets you there. I'm not saying don't run 100% meth, 50/50, or all water. They all have different advantages that must be tuned for to actually realize.

Now, what will I be doing? I'll probably be doing what I can afford and making a compromise with a 50/50 non-progressive kit since I already have one, and shooting it in the charge pipe about a foot in front of the TB. If I could do it the best way I see fit for me, it would be a small nozzle water or 50/50 mix in front of the impeller, and big nozzle 100% meth at the throttle body. There is more than one way to skin a cat.

EDIT: If you read all the way to page 6 then you will see why I added this info here. It's simple and directly from "Engineering Fundamentals of the Internal Combustion Engine" by Willard Pulkrabek. If you take away anything from this thread, I hope that it is a desire to read this book or the much larger "The Internal Combustion Engine in Theory and Practice" vol. 1&2 by Fayette Taylor.
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Mitsu EVO they came factory w a water sprayer.

water spray for the intercooler maybe, not water injection.

An old Saab turbo is the only car Ive ever heard of that came with water injection from the factory.

But water has infinite octane, so IS the better detonation suppressant. Water will also cool chamber temps better too.
But obviously water itself can have a negative impact on combustion if too much is used, and that's the caveat.

Most people just want to inject and dump a shitload in with no real metering or precise control. So in this case methanol works great. The engine will always be able to consume it all with almost no negative effects, it will cool charge and it will add octane.
But it does require much larger volumes of fluid to do so. Plus methanol is poisonous, flammable, etc etc
Water is safe.

Really, just depends what you're trying to achieve and how efficiently you want to achieve it.

I agree OP it all depends on what your trying to do. Usually when one runs 100% meth is because its also being used as an additional fuel source as well as the cooling benefits. So its fair to say that for a lot of guys around here 100% meth is the only way to go. A 50/50 mix Probsbly isnt going to cut it on a 750 WHP blown corvette. :thumbs:

Why ? Ultimately it will be safer than 100% methanol because of the better cooling and detonation suppression.

It's just a case of injecting the right quantity. It may be a little easier to make the power on 100% meth, but 750whp is very doable on pump alone, nevermind using some extra means to achieve it.

:bigears

evo and sti cam w a ic sprayer

It will be a lot easier. How many cars around here make a legitimate 750 reliable whp without meth?

750 WHP is a lot of power ya know. :)

I know it is. As to how many, I dont know. As for dyno number reliability for that number, that's another matter too.

Ive made anywhere from 680 to 850rwhp on pump fuel only. Except the 850 was with a badly misfiring engine. So which do you believe ? I certainly dont believe the high number, and the low number I know is a very conservative Dyno Dynamics.
I dont believe any dyno numbers. And dyno's in the US seem to read much higher than most in the UK too. Although Dynojets arent that common here.
I trap 1/4, 1km and mile much faster than many local cars claiming huge amounts of power more than me, and in far lighter and more aerodynamic cars.....so really, most of them must be BS.

But I also know I make a lot more power on 60/40 meth/water.

Most seem keen just to shoot straight for meth over some fears about pump fuel. I dont know how bad fuel is over there, but we only get 93 PON over here, and Ive never had any issues with it.

I can easily make 500hp on 4cyl turbo engines on pump fuel, and I can easily make whatever power my own LS engine makes on pump fuel too with no reliability issues.

In fact, the only times Ive had engine failures...have largely been down to meth system problems.

Which is safer ? that could be debated too.

Out here in California 91 is our premium fuel. There is a gas station here in San Diego that has 100 octane at the pump though.

I ran a home made water injection on the roots supercharged, non-intercooled Rx7. I just sprayed water above the supercharger into a throttle body vacuum port. A thermocouple mounted below the supercharger showed a nearly instantaneous drop of 50 °F (but still significantly above ambient). Its been a while so I don't remember the max temp drop.

Yeah, I guess that's a little unclear about what injection means. Direct Water Injection (DWI) to me means you have direct injection to the combustion chamber, but I use injection interchangeably without noticing. The other way, that all of us would use, is referred to as charge air humidification.

Yep, but I don't know what that limit is and I don't think anybody will get close to that limit to find out. To put it into perspective, "Water and fuel are injected in a typical water-to-fuel ratio of 0.4-0.7:1, reducing NOx emissions by 50-60 per cent without adversely affecting power output or engine components."-from Doug Woodward's book I mentioned earlier. This is from examples on some Wartsila engines using DWI and charge air humidification, btw. That's a lot of water:willy: Before you reach those water amounts, you would run into cylinder liner wear problems.

Yes, people do inject a bunch of meth without precise metering or control, and that's my biggest concern with it. There is no way to calculate your AFR/equivalence ratio/lambda on paper using such basic methods of injection, so you have to rely on a wideband sensor that will tell you lambda to figure out if you are supplying the right amount of methanol with your fuel.

And you can inject too much methanol by running it unnecessarily rich. Water has a higher enthalpy/latent heat of vaporization than methanol, so why would you bother running an excessive amount of methanol if the goal is to prevent detonation?

aint no need to argue about it... the people who actually race and been doing it along time already know what to do... and there is no point in trying to help people because the reality is to be a "grue" on this or any site, all you have to do is post a lot and repeat whatever it is someone else said.. that's is.. then is become somehow "fact" and then it just gets repeated over and over again... WW2 planes used water injection long ago.. its been around forever because it works.. the only reason it don't work on a "corvette" is because someone cant make $600 on it and corner the market..

Thanks, you're very right. I think I'll leave it at that.

So let me get this right? People say meth kit X essentially won't work with a corvette because it dont cost 600 bucks? And that the manufacturer who makes a meth kit that cost 600 bucks corners the market because of good marketing?

Id like to think that injecting 100% methanol into an engine would require a superior pump lines and fittings for starters.




Taken from AEM's website: "Methanol is a toxic and highly flammable chemical. 100% Methanol ignites easily and burns vigorously with an almost undetectable flame. Methanol can be absorbed through the skin and even small amounts can cause blindness or even death. Using this fluid at high pressures, without dilution, in an under-hood environment with nylon lines and push-to-connect fittings is very unsafe. The performance advantages of using greater than 50% methanol concentrations are small, if they exist at all. However, the safety issues are very real and far outweigh any perceived benefit of running high concentrations of methanol."

Taken From Alky Control's website: "Our systems are designed for off-road-use only. While we cannot encourage the container to be filled with straight alcohol while the vehicle is operated on public roadways, making the solution of alcohol 50/50 by mixing with water makes the alcohol non-flammable. Or using straight water versus any alcohol. We cannot assume any liability for any damages incurred by the use of a flammable liquid in a passenger vehicle. And keep in mind, there is probably a greater threat from a gasoline tank filled with 20 gallons versus a gallon of alcohol. So discretion is advised, and hence why braided hoses are used with our systems to minimize any risk associated with a flammable liquid."

What can be learned from reading both of these passages taken from each site is that both company's do not recommend the use of 100 percent methanol. However they dont recomend it for different reasons.

Aem is essentially because they say its dangerous with their lines n stuff because the lines could come apart during operation.

Alky control is essentially because they cant encourage the use ofa100% methanol on public roads. They go on to say that it has nothing to do with their lines being incapable.

Bottom line is that you get what you pay for. I litterally had the lines come apart during activation when I had an AEM kit.

Excluding alky control, the lines on every other meth injection kit are not any different from AEM.

I haven't even began to the output capabilities and internal components of the other pumps vs alky control. Let me summarize it. They all fall short in comparison.

That is not at all the purpose of the information I was hoping to convey in this thread, nor is it relevant to anything that was said. Please read the link in the original post. I really don't want this to turn in to another debate about which company's pump and lines are best.

I run mainly pure distilled water in my injection setup. I'll put maybe 5% by vol of methanol or isopropyl to decrease the surface tension of the water and allow better atomization.

If you don't have large enough fuel injectors then meth is a good way to reduce duty cycle. If you have injectors sufficient for your power levels, as much water as you can until it bogs.

No surprise diesel guys like the water injection. I am sure their IAT temps are a lot higher than a gas engine running 10-20psi.

I wss just responding to a comment.

on that note to get your thread back on track. I find that most people using methanol in applications here are doing it for not just cooling of the air charge but also as an additional fuel. However if your just after the cooling effect of Water/methanol injection than by all means run water or a 50/50 mix. Though I would think that one may want to consider a more efficient intercooler if possible. A wideband has been pretty proven to be an effective means to assisting in determining a proper AFR. Wideband is the only way to determine a proper AFR. There are way too kany variables to try to pen and paper calculations. Engine rpm, dynamic cyl air elevation engine load.

Methanol has less BTU's than gasoline. It is ignorant to add meth, and pull gasoline for fuel. I am a believer in water from my own findings. I also am an advocate of spraying in front of the blower. I run a 3gph in front of my blower, and it picks up boost, and cools the air at the source. Nice read OP.