Methanol/water injection

[plovett]

When you inject a methanol/water mixture into an intake tract, as in a supercharged application, does the methanol add a combustible component?  Or is it just for cooling?

thanks,

paulie

[BigBlueIron]

Methanol in itself is a fuel. So yes to your question.

[Falcon67]

Methanol carries oxygen with it also. 

[plovett]

So does it affect the air/fuel ratio then?  Or is the amount injected primarily for a cooling effect insignificant in that respect?

thanks,

paulie

[BigBlueIron]

Yes it does. It really depends on what meth/water ratio your running and how much total injected. A good reason to use Lambda in tuning as 1 is stoich no matter the fuel or combination of fuels.

But with it comes cooler (more) air due to latency of evaporation (of which methanol is more so than water) so it might not need much of a change from where your at now, as said depending on mix and quantity.

I'm currently setting up a twin stage system for my LPG turbo project. Can't wait to try it but its winter now so I have stopped fiddling with it 

[frnkeore]

If I was going to mess with that, I'd make sure I had a Oxygen sensor to make sure it doesn't run to lean when under power.

[cammerfe]

Running my ECTA car, (E/F CC) I have a 'spray' system that uses methanol as the fuel along with the nitrous oxide. It's literally impossible to add too much methanol. unless you go so far that there's enough methanol in the cylinder to cause a hydraulic lock when the piston comes up to top dead center on the compression stroke. In that case you'll bend a rod or crack a piston or some such. But even a mix so rich that it  approaches 4:1 is not unheard of.

I set the 'E' fuel competition coupe/sedan record, and then re-set it twice more the same day, and the only change I made each time was to go up a couple of numbers between runs on the methanol jet. Then I ran out of jets, so, who knows? Maybe I could have gone faster yet!

KS

[olman]

Does anyone remember Edelbrocks "vari-jection" from the past? I ran one on a 66 428 engine and never heard a knock. They recommended using windshield washer fluid in the reservoir.It was on that truck for over 2 years then sold the truck, Simple and effective.

[GerryP]

There were systems long before Edelbrock's -and yes, I do remember it.  The Olds Jetfire turbo from I think around 1962 used what they called Rocket Fluid, which was, for the most part, windshield washer fluid to quell detonation.

Snow is probably one of the industry leaders in water/methanol injection for both carbureted naturally aspirated to injected boosted applications.

[4twennyAint]

I have a Snow Performance kit on a supercharged 302 mustang.  Best money I ever spent.  It makes the overall fuel curve rich, and you  lean out the Gasoline.  I can run 15 PSI boost and still 38 degrees ignition advance.  Actual power gain over race fuel just using pump 93. 

[gregaba]

I have been wondering about this for a few years so now I will ask the experts.
I was wondering what effect good or bad it would have on a higher compression non boosted street engine.
I would like to run 91 octane as that is all I can get around here without going to race gas.
If it would run good and not hurt my engine I would run the Snow unit.
Thanks
Greg

[plovett]

I was wondering what effect good or bad it would have on a higher compression non boosted street engine.

I have heard of people running methanol/water in non-boosted applications with good results.  The engine doesn't know if it is boosted or not. It just knows if the cylinder pressure and temperature are too high for the fuel's octane.  That could be because of boost or mechanical compression ratio, or other things.

JMO,

paulie

[GerryP]

Water injection systems were VERY common in the '60s and '70s on naturally aspirated engines.  You wouldn't believe how common it was for guys to be running 12:1 pistons on the street.  And, yes, 3/4 race cams, dual quads, tunnel rams, Thrush mufflers (or Purple Hornies) and chrome everywhere.

It helps to understand how a water/methanol (or just plain old denatured alcohol) works.  The one obvious side is where the mix is injected into the intake manifold.  We know this helps to cool the intake air through both the latent heat of evaporation, which means that heat in the system is being removed just through the chemical process of evaporation of the liquid, and the presence of a cooler liquid medium that helps to absorb heat even though it has not evaporated.  The other way the mixture helps is in the combustion chamber.  Here, the same evaporation process is taking place but the affect is more dramatic.  As the piston is rising, whatever is in the combusion chamber is being squeezed.  As you know, when you compress gasses, it raises the temperature.  This heat vaporizes the liquids in the combustion chamber and in that process, latent heat is being removed making the fuel/air mixture less susceptible to abnormal combustion.

Water injection has never gone away.  It's just that the circumstances that brought them to prominence kind of passed by when we knuckleheads quit building 12:1 street engines.  The systems out there, like the Snow system, got new life with the advent to boosted systems.  But they do make systems for naturally aspirated carbureted engines and they work just the same today as they did 70 years ago.

Here's a useless fact:  B-52 bombers use water injection to increase engine thrust.  Those eight turbofans hanging off the wings are what are called volume engines, meaning the thrust is based upon the volume of air going through the engine.  And just if you were interested, a Turbojet is a pressure engine, meaning thrust is a consequence of gas pressure.  One way to increase volume for the Turbofan is to use a liquid that vaporizes.  In this case, the B-52 uses distilled water.  It's injected into the engine and the volume difference between an atomized liquid and a vapor is roughtly 600 times.  So you get more thrust in the process of the rapidly expanding vapor.

[machoneman]

Water injection systems were VERY common in the '60s and '70s on naturally aspirated engines.  You wouldn't believe how common it was for guys to be running 12:1 pistons on the street.  And, yes, 3/4 race cams, dual quads, tunnel rams, Thrush mufflers (or Purple Hornies) and chrome everywhere.

It helps to understand how a water/methanol (or just plain old denatured alcohol) works.  The one obvious side is where the mix is injected into the intake manifold.  We know this helps to cool the intake air through both the latent heat of evaporation, which means that heat in the system is being removed just through the chemical process of evaporation of the liquid, and the presence of a cooler liquid medium that helps to absorb heat even though it has not evaporated.  The other way the mixture helps is in the combustion chamber.  Here, the same evaporation process is taking place but the affect is more dramatic.  As the piston is rising, whatever is in the combusion chamber is being squeezed.  As you know, when you compress gasses, it raises the temperature.  This heat vaporizes the liquids in the combustion chamber and in that process, latent heat is being removed making the fuel/air mixture less susceptible to abnormal combustion.

Water injection has never gone away.  It's just that the circumstances that brought them to prominence kind of passed by when we knuckleheads quit building 12:1 street engines.  The systems out there, like the Snow system, got new life with the advent to boosted systems.  But they do make systems for naturally aspirated carbureted engines and they work just the same today as they did 70 years ago.

Here's a useless fact:  B-52 bombers use water injection to increase engine thrust.  Those eight turbofans hanging off the wings are what are called volume engines, meaning the thrust is based upon the volume of air going through the engine.  And just if you were interested, a Turbojet is a pressure engine, meaning thrust is a consequence of gas pressure.  One way to increase volume for the Turbofan is to use a liquid that vaporizes.  In this case, the B-52 uses distilled water.  It's injected into the engine and the volume difference between an atomized liquid and a vapor is roughtly 600 times.  So you get more thrust in the process of the rapidly expanding vapor.

Wasn't the B-52 engine's water injection used only on takeoff? I thought it was after watching long ago a whole squadron of BUFF's taking off from a North Dakota  AF base.

[GerryP]

Yes, just for takeoff.  Loaded with weapons and fuel, it was on the porky side.