Why alcohol instead of water?

[FastGSXauto]

From reading your threads, you guys seem to run primarily alcohol, with some water to keep it less flammable. I don't understand this. The objective of my water/acohol injection is to get cyclinder air temperatures lower to prevent detonation.

True, water does not provide any fuel, which is a necessary part of the combustion equation. However once we are over the stoich ratio of air to fuel, no more fuel is needed for the combustion. And we are well over stoich already with out fuel systems. In fact additional fuel ( or water ) makes less power because it displaces the air. But this allows us to run higher boost, which outweighs any losses.

So we are injecting water/fuel purely as an anti detonant, not as a provider of combustion fuel. With this established, the properties of water are superior to the properties of methanol, ethanol, isopropyl or any other alcohol. Specifically, the latent heat of fusion is 3 times as high in water as in the others. This property is the amount of heat absorbed when the liquid changes to a gas, which is where the majority of the air cooling takes place. In addition, water has infinite octane. It will not flash ignite. So my question, why are you guys using alcohol instead of water? I really want to know if I am missing something.

 

[BLACK6PACK]

I'll let the experts chime in here. GM tested the Grand Nationals with water injection. We actually have an idiot light in all the turbo buicks that says "POWER INJECTION". They found that there was slightly more wear on the engine and that is when they decided to go the intercooler route.

The reason that I know why we use alky is because it works. We have guys that have tested it all. The easiest to tune with is 100% denatured. From the gurus, the best power can be had with 50/50 water and methanol. A lot of guys run out of injector, so injecting alky not only lets them run a lot of boost and timing it also is a bandaid for having injectors that are too small.

 

[Brian Schauder]

I have a homemade alky injection set up made by Louie Lopez .
I run isopropyl and water 50/50 mix with a shot of wd-40 in it.My car really seems to like the water for some reason.If I use 91% alky with that mix instead of the 70% I get knock.If I run more the 50% alky I get knock.If I mix heavy on the water I don't get any knock.I have no idea why it works this way so I can't answer your question,but thats what works for my set-up.My boost is set at 23-24 and I never see any knock,unless my jug is empty!!

 

[FastGSXauto]

So why dont' you run straight water? That's what I was proposing in this thread.. just because something works, doesn't mean it can't work better. I only use alcohol in the winter to keep from freezing. BTW, I just tuned for about 2 hours. Did about 15 0-70mph pulls. I tried several runs with windshield washer fluid, pure water, and water/denatured 50-50. From my logs, water appears to work the best, though they are all pretty similar.

 

[Brian Schauder]

well you can always improve on something,but I'm kinda from the school of "if it's not broke don't fix it".What I really like is not even having to worry about knock at all.I usually just hit the recall on the scanmaster to see if I had any,never do,so that's why I just do the same thing now every time.

 

[DMan]

From reading your threads, you guys seem to run primarily alcohol, with some water to keep it less flammable. I don't understand this. The objective of my water/acohol injection is to get cyclinder air temperatures lower to prevent detonation.

This is true. But I don't really run water to make it less flammable. 50/50 burns plenty good. Its more the other way around. Start with water but you will find that you need more fuel at the high boost levels. More below.

True, water does not provide any fuel, which is a necessary part of the combustion equation. However once we are over the stoich ratio of air to fuel, no more fuel is needed for the combustion.

While true on paper this ends up being different in practice. Most vehicles make maximum power at air fuel ratios that are richer than stoichiometry, typically around 12-12.5:1.

And we are well over stoich already with out fuel systems. In fact additional fuel ( or water ) makes less power because it displaces the air. But this allows us to run higher boost, which outweighs any losses.

If you go too rich your engine make less power because there is not enough air to burn all the fuel. The mixture is too rich and can't burn properly, if at all.

So we are injecting water/fuel purely as an anti detonant, not as a provider of combustion fuel.

I agree, but alcohol is a provider of combustion fuel, regardless of what you think you are adding it for. Alcohol is a fuel, and does affect your air fuel ratio. Also, alcohol has a higher octane number, so it inherently resists knock.

With this established, the properties of water are superior to the properties of methanol, ethanol, isopropyl or any other alcohol. Specifically, the latent heat of fusion is 3 times as high in water as in the others. This property is the amount of heat absorbed when the liquid changes to a gas, which is where the majority of the air cooling takes place. In addition, water has infinite octane. It will not flash ignite. So my question, why are you guys using alcohol instead of water? I really want to know if I am missing something.

I use alcohol for the following:
1. It increases the amount of fuel you are adding to the engine
2. It increases the fuel octane rating because alcohol has a higher octane rating.
3. While it has a lower heat of fusion, it also evaporates at lower temperatures and should cool the intake charge better than water alone.

I tried using water only when I first started with water/alky injection. Results were good. I recall using blue tops and a thrasher 108 chip I was able to get to 21-22 psi boost with just water before the engine started to knock. Not bad for free anti-detonant. At that point, I needed to add more fuel.

I then had the goal of trying to get rid of all the alcohol by using 50# injectors so I would get all the fuel I needed, and deliver only water. The test never really reached completion as I was plagued with a bunch of other electronic glitches.

However, I have done testing with water and water/alky. In general, the car runs harder and faster when you inject a mix of water alky. Water does a good job of suppressing knock, but water alky just makes the car run like a bear.

Hope this helps.

 

[FastGSXauto]

Ok, I think I understand why you guys use alcohol now. Too add supplementary fuel because you are not getting enough from your injectors. Correct? In my case, I have plenty of fuel from the injectors. I run 550cc/min (4 injectors), and I only get to about 80% duty cycle at 20psi. At this point I add just water to supress detonation. I like this method because I can fine tune my A/F ratio to make optimal power at lower boost, then at higher boost, it keeps the same ratio, but I use water as an anti detonant.

 

[boostm3]

This whole issue seems to beg out for more research....Enlightened opinions run all the way from recommending 100% water to running 100% alcohol. If you read Aquamist, youll get the distinct impression that all they recommend alky for is to prevent mixture freezing in the winter. Over and over again, we are told that '...Water has Infinite octane...it never burns...', etc, in defense of using it. If you hang out at all on these pages, you get the distinct opposite impression, ie, that Alky is god, and water is there just as a transport medium to support the alky.

So, Im glad that FastGSX started this thread, and others have contributed...Still, when all is said and done, we have some minor experiential data, and opinions which run all over the lot...What we dont have is concrete data in support of what the best mixture is...To complicate things, its entirely possible that different individuals perform better on different mixtures . Yet, if we can make the statement that, in general, the best power is made at 12.5:1 air to gasoline, then we should be able to come up with some benchmark values for mix content.

Maybe, this still will happen. The whole water/alky injection phenomenon seems to be expanding to different markets....Its recently entered the bMW aftermarket with the help of Active Autowerkes, and Aquamist. Its been in the Saab aftermarket thanks to KCSaab. So, more exposure is coming..And with that, we should have more results to look at.

 

[BLACK6PACK]

Just to throw another variable into the mix, our cars tend to run better at 11.5-11.7 to 1 mixture.

 

[Turbo__Tim]

Maybe others can run water because they have smaller engines, and therefore don't have as much heat to get rid of to bring the temperatures in line. We need more water to do the job.

To get that much pure water in our engines would require greater misting ability than we have. Our pumps would need to be twice as powerfull, and the individual nozzles much smaller. even then there would be a limit before the spark is doused.

Lacking this super atomization ability we are forced to a 50-50 mixture. The water droplet nucleus in suspension, is surrounded by alcohol. (Kinda like a circle, with a dot in the middle, the dot being water....I have seen pictures)This allows the combustion to take place, without the water interfering. After combustion, the remaining water droplet (which has now become vapor, or as you know it as steam) is pushed out of the engine, taking with it the heat it has absorbed.

Lets say that the water is the medecine, and that the alchy is the sugar coating that helps it pass through the system...

Of course I could be wrong, I often am....

 

[blackbuick87]

Straight water is just too finicky to tune with our setups. I was getting knock with straight alcohol also, and went down to < 1* simply by switching the mixture alone. Steve Hill and many others have done the experimenting for us so that we dont have to. The guys running water only usually have three to four nozzles at least. That is way too complex for me. I and most others here want to be able to install our homemade or plug and play kits, turn up the boost, and haul a$$ without too much tuning. It is just to easy to flood out the fire with straight water

 

[boostm3]

Maybe, another thing which might help explain why the buick guys like the alky predominant systems, and we like the water predominant, or at most, the 50-50 systems, is that our inline 6 3.2l engines have a static CR of 10.5. and I belive the GN engines have considerably less..In addition, our engines are iron block/ alum heads, and I belive the buicks are all iron...right? Perhaps the CR and the Content of the engines contribute to a different behavior of the various mixtures within the cylinders.

 

[spins4]

Maybe the reason is because if you spray alcohol you can reduce the 93 gas from the injectors and substitute that with alcohol. In this way, its like "mixing" race gas into the combustion chambers, similar to mixxing pump/racegas at the tank. I do not know enough chemistry to comment on the difference of water and alcohol on cooling, etc, but it seems alcohol is a better way to raise the octane, and water just lowers the temps? Just a shot in the dark.

 

[Turbo__Tim]

The percentage of alchy in the mix is too small to affect the octane. We are talking a 30-1 ratio. Not even 1 octane point.

blackbuick87 has got it right...

 

[DMan]

Hey Turbo Tim,

Something sounds off with yor 30:1 ratio. Check your calculations. Something tells me its smaller than 30:1.

 

[Turbo__Tim]

You just wouldn't believe how many times I am wrong...

OK let's see, alchy used during 1320= 6 ounces (tops, I use 3)

50-50 mix = 3 ounces of alchy.

Fuel used during a run= 60 ounces

Ok 20 to one?

The ethanol content in gasoline used to reduce emissions is 10%(10-1) And we all know what that does to gas mileage! (reduced power)

BTW Ethanol is only 90% pure. 5 percent water, and 5 percent poison to keep us from drinking it, and avoid paying the federal excise tax on alcohol... If you are running 'pure' denatured, you are really running a 90-10 mixture.

My car uses a 40-1 fuel to water mix, and I manage 21 psi. (3 ounces of 50-50 mix per 1320, or 1.5 ounces of water). That is with (2) 1 mm. Aquamist nozzles, 1st nozzle comes on at 5 psi, the second @ 15 psi.

Most people using the Aquamist nozzles need (4) 1 mm nozzles.
My car is a bit of an exception. I've had a lot of trouble tuning the alchy inj. after switching to alum. heads...

Also I'm far from being an expert on combustion, but the tiny quanity of alchy in the mix tells me that the octane boost comes not from the alchy, but from:

(1) The mist that is mixed in with the gas charge. The mist prolly seperates the gas molecules so they cannot burn in a straight chain, slowing the burn time.

(2) The cooling effects of the water that is left over after combustion. This steam takes heat away from things like valve surfaces, and tiny pieces of carbon, that if allowed to heat up would ignite the intake charge as it is drawn into the combustion chamber. Pre-ignition like this is what blows head gaskets, and punches holes in piston tops, since the charge is mostly ignited before the piston begins the compression stroke. Might as well put a rock in there...

JMO, I could be wrong, I often am...

 

[boostm3]

The percentage of alchy in the mix is too small to affect the octane

But its not too small to impact the a/f ratio.

Here's how using just a 1 mm aquamist nozzle, can enrich my afr by half a point.

50% methanol from a 1mm jet equates to approx to 165 cc of methanol per minute. For 350HP requires approximately 2 litre of fuel, the methanol ratio to fuel is 165cc/2000cc or 8% - methanol has 1/2 the calorific value of gasoline, so extra fuel injected is only 4%. If Im at 12.8:1 at my leanest when under full load, teh methanol used this way in the 50/50 mix would enrich this to 12.3:1 or half an afr point....Its not alot, but it absolutely can make the difference between knocking and not! Now, running 100% methanol in this quantity, if your engine can take it, would obviously double that, adn reduce the afr by 1 full point!

 

[turbov6joe]

I've been running 100% denatured with good results. After reading this thread I decided to try a 50/50 alky-water mix at the track and see what happens. Prior to this I could run 21 psi with 92 octane with a max pump speed setting and have almost no knock retard. With the 50/50 mix my KR was in the upper single digits all night untill the resevoir starting running low and I added 100% alky back to the mixture. As I added 100% alky, the KR got continuely lower all night. Right now I'm using a Jay Carter street chip with OE squirters and turbo. What gives???

 

[boostm3]

mix my KR was in the upper single digits all night

Whats a KR? Knock Ratio? What then...I think that whats true for my car may not be true for yours...Consider that on my '99 M3, first, Im running OBDII engine management; youre not...Second, my static compression ratio is 10.5:1...Youre at least 2 points below that. Third youre engine is all iron; mine's got alum heads. Fourth, Im running a Centrifugal supercharger; youre not. Fifth, Im running max boost of 11 psi; youre probably more than twice that. And on and on and on....Its been proven that on my type of car, alky over 50% will actually raise the in cylinder temps...I dont even know if thats limited to my type of car either, as Aquamist also makes this statement on their website, consequently, their pumps arent even designed to handle more than a 50/50 methanol mixture without swelling the seals. Denatured is a no no for the aquamist pump, according to aquamist, because ethanol will swell the seals in concentrations greater than a lowly 5%!

In addition, I think the goals may be different...ON our systems, most Centrifugal supercharger kits for our M3s come with no intercooler. And most are 6 psi systems, that dont really need it...IN my case, Im at 11 psi, which is why I needed the water/alky injection...But the main function of it is to function as a gaseous intercooler, ie, to cool the chamber and prevent knock. Its been proven time and time again, that water has a greater cooling effect than alcohol, and the main reason alky is used in the system at all is to prevent freezing, and to facilitate evaporation; not as the main cooling agent...Water when it evaporates cools the environment much better than alky! Greater heat latency. But....you guys have intercoolers already...Alky in your systems does double duty as a fueling agent...In many cases, I think this is its prime function...Alky when used at 100% can enrich your fuel mixture by over 1 whole afr point! Even at 50% on my system, it will enrich the mix by a half afr point.

So, in trying to come to grips with these differing goals and differing results, I can only think that the difference in platforms has an awful lot to do with it....If someone else has another take on this, Im sure wed all love to hear it, because its still somewhat of a mystery.

 

[89 SHO/SC]

Originally posted by boostm3


...Its been proven that on my type of car, alky over 50% will actually raise the in cylinder temps...I dont even know if thats limited to my type of car either, as Aquamist also makes this statement on their website ....

In addition, I think the goals may be different...ON our systems, most Centrifugal supercharger kits for our M3s come with no intercooler. And most are 6 psi systems, that dont really need it...IN my case, Im at 11 psi, which is why I needed the water/alky injection...But the main function of it is to function as a gaseous intercooler, ie, to cool the chamber and prevent knock. Its been proven time and time again, that water has a greater cooling effect than alcohol, and the main reason alky is used in the system at all is to prevent freezing, and to facilitate evaporation; not as the main cooling agent...Water when it evaporates cools the environment much better than alky! Greater heat latency.

I have purchased a SMC kit and am installing it on my Taurus SHO. Like you I'm running a Centrifugal Blower, however I'm running more boost than you are without an intercooler (14psi).

Could you share the "proof" that anything more than 50% Alky raises intercylinder temps ? (links, source, etc...) A bunch of our friends here and their Gurus have switched over to 100% alky. I'm planning on increase my boost 1-2 psi and not blowing up my engine is important