Merits of water in a mainly methanol mixture?.

[keithmac]

Hello all, I`m currently running a 75% methanol 25% water mix injecting approx 1200cc/min. This gives me roughly 300cc/min of water injected by port and post turbo as part of the mixture,which is 15% of the fuel injected.

I`m due to fill the tank again and was mulling over wether to stay 75m25w or just go for pure methanol, it`d be easier just to fill with metanol, no mixing but I don`t want to sacifice the knock reducing properties of the water?. Does injecting at these higher volumes negate the effects of the water?.

My other though was that the water content was also reducing the corrosive effects of the methanol on my aluminium inlet manifold etc and may be worth keeping just for this reason?.

I`ve tried many mixtures and flow rates to eradicate knock on my engine and have come to the conclusion that it`s octane limited, hence the high volume of methanol used.

Would like to here some input from anyone who`s injecting 1l/m or more and what mixture you found to be best?.

Cheers, Keith.

[JohnA]

Methanol doesn't do much with in-cylinder cooling though.
If you have temp spikes during the compression stage it is the water mist that will absorb it, not the methanol.

[keithmac]

Cheers John, I`ve stuck with the 75% methanol 25% water mix as it`s proven to work very well on my setup. If it ain`t broke don`t fix it..

[JohnA]

Methanol evaporates very quickly, and it helps the water mist disperse more uniformly. It also adds some octane and calorific value.
But it cannot match water's latent heat of evaporation.
They work as a team :smile:

[dudical26]

I know this thread is a bit old but I just saw it.

I use two 1.0mm nozzles with my HFS-5 kit and spray 100% meth. I had the thought that when you spray that large a quantity of fluid, even if eater is better at cooling then meth, it doesn't matter anyway. There is so much meth being sprayed that I think it cools it enough, and I would rather gain the benefits of the octane of meth.

[JohnA]

Yeah, for pure intercooling meth is preferable.
Water is not very good at reducing charge temps, it's 5-10C reduction if you're lucky, usually less.

For chargecooling in the cylinders (during the compression stroke) water is preferable. It does away with the need to run rich under boost.
This effect you can only see with a knock detector though, not intake temp gauge.

[djuosnteisn]

I wanna make sure i understand this correctly.

Intercooling is reduction of temps in cold pipe and intake mani correct? And methanol is more effective for this.

Charge cooling is reduction of temps in the cylinder, and water is more effective for this.

So if one is spraying to reduce knock, water is the best option as it cools the cylinder most effectively (with some meth added to help dispersion & some intercooling). Once knock is eliminated, timing advance and higher boost levels can be had.

I just don't see the benefit of spraying mostly methanol, other than that let's you lean the mixture out a bit. I don't understand how much power is able to be had in a setup like this (though i've seen graphs showing higher mixes of methanol resulting in much more power than water alone).

(john, i just posted a similar question in the gasoline forced induction section, and it should have been here. Feel free to delete the redundancy!)

[JohnA]

I wanna make sure i understand this correctly.

Intercooling is reduction of temps in cold pipe and intake mani correct? And methanol is more effective for this.

Charge cooling is reduction of temps in the cylinder, and water is more effective for this.

So if one is spraying to reduce knock, water is the best option as it cools the cylinder most effectively (with some meth added to help dispersion & some intercooling). Once knock is eliminated, timing advance and higher boost levels can be had.

I just don't see the benefit of spraying mostly methanol, other than that let's you lean the mixture out a bit. I don't understand how much power is able to be had in a setup like this (though i've seen graphs showing higher mixes of methanol resulting in much more power than water alone).

(john, i just posted a similar question in the gasoline forced induction section, and it should have been here. Feel free to delete the redundancy!)
Technically, the terms 'intercooling' and 'chargecooling' should be interchangeable.

Methanol evaporates very quickly absorbing heat, so it is best on the way to the cylinders.
Water mist is very efficient in absorbing heat during the compression stroke, so it is best inside the cylinders. As it changes state from liquid to gas it absorbs a LOT of heat.

The exact meth/water mix that is best for an application depends really on whether you have intake temps well above ambient, and whether the mechanical compression ratio is way too small for the amount of boost you're running at full throttle. For example, if you're running a CR of 6:1 and 2 bar boost, you wouldn't see much benefit from in-cylinder intercooling.
But if you're running a CR of 11:1 and 2 bar boost, then you need all the in-cylinder intercooling you can get, because you are pushing your luck with pump fuel (race fuel wouldn't benefit though nearly as much).

Both can claim intercooling effects, but at different times in the path of the air charge.
You can have both if needed, they are not mutually exclusive. :smile:

[djuosnteisn]

Thanks!

So in a high compression ratio, high boost system, best performance gains can be realized with a majority water mix, with only some methanol to aid in dispersion and manifold temps.

It's still a bit of a mystery to me then, why some would spray majority methanol mixes, unless they had maxed out injectors? Unless, since the methanol is more effective at cooling "on the way to the cylinders", it creates a far denser intake charge than water would, and thus net more performance gains?

Sorry for the noobness, but i think WI is by far one of the coolest things i've done to my car ever. Just want to understand it fully.

[djuosnteisn]

After reading other threads on this forum, i think i have a fundamental misunderstanding.

Some people speak of the methanol as the main agent for octane boost, and the water as the main agent for cylinder temp reduction. But in my mind, the cooling effects of water would increase the effective octane, right? Less chance for knock = higher octane?

[maxc]

After reading other threads on this forum, i think i have a fundamental misunderstanding.

Some people speak of the methanol as the main agent for octane boost, and the water as the main agent for cylinder temp reduction. But in my mind, the cooling effects of water would increase the effective octane, right? Less chance for knock = higher octane?I've been reading that just water is good for 10 too 20 octane points higher.
I have run very lean fuel mixtures and very high compression with just water.
The trick is getting the too "mixed" before they reach the cylinder.

[djuosnteisn]

I guess my application is even more difficult. I run a mazdaspeed6 with direct injection. So the final mix (fuel to spray) happens in the cylinder. I'm just trying to understand the difference in benefits from mostly methanol, to mostly water.

I've got a single nozzle setup on my cold pipe (315cc/min), maybe 4 inches from throttle body, and it works great.

Just installed a kit in my buddy's car, and decided to do a dual nozzle setup (smaller nozzles, total of 380cc/min) and he's still seeing knock. We're running the exact same map, boost etc. I have a better cold pipe though, that goes straight into the TB. He's bends a bit. I want to see what mix would best benefit his setup, and get rid of his knock.

[JohnA]

...So in a high compression ratio, high boost system, best performance gains can be realized with a majority water mix, with only some methanol to aid in dispersion and manifold temps.
.
yes
..why some would spray majority methanol mixes, unless they had maxed out injectors? Unless, since the methanol is more effective at cooling "on the way to the cylinders", it creates a far denser intake charge than water would, and thus net more performance gains?.
A denser charge yes, but not by much. A few percentage points at best in real life...
Maxing out the injectors is not that hard a problem to fix either, increasing fuelling is not that hard (compared to increasing the oxygen content!)

If your intake temps are slightly above ambient under boost (say 10-30C) , then there is not much to be gained by intercooling at that stage. You'll get a small density gain and some safety margin (from detonation)
If on the other hand your intake temps under boost are way over ambient (say 100C) then intercooling before the cylinders is essential. Even spraying water mist would have a serious effect in charge temps in that case. Methanol would help even more.

It all depends on which links are the weakest ones in your power chain.

[djuosnteisn]

John, you rock! :D
Thanks so much for your feed back, and helping me understand the process! I look forward to learning/sharing more in this community!

[JohnA]

.... But in my mind, the cooling effects of water would increase the effective octane, right? Less chance for knock = higher octane?
sort of - if you think of 'octane' as the fuel's reluctance to self-ignite. Just like race fuel, it allows you to run higher comp ratios and/or higher boost pressures without detonation.

Beware that such generalisations and statements are full of holes though, assuming other factors such as ignition advance etc are all equal (which they never are!)

[keithmac]

I found my car to be "octane limited" to want for a better description on 97 ron petrol. Running 1l/min of methanol when on boost (and 250cc/min water) allowed me to add 6 degrees of ignition timing, which I had to take out before (at 20 psi manifold pressure).

I`ve since switched over to E85 as my main fuel, this has better octane rating than 97ron petrol and I now don`t need the meth/water at all (for the same conditions).

I had limited results with water only, much better with 75%methanol 25%water.

[djuosnteisn]

Thought i'd post some other interesting benefits to higher methanol ratios that i've learned of recently.

Probably the best one i've learned about is how methanol is partially oxygenated by itself. This most likely accounts for the lower stoich ratio of (IIRC) 6 to 1, Air to Meth. Since air is usually the most difficult ingredient of combustion to get into the engine, running higher percentage of methanol helps bring more air to the party. Also it does have a higher octane rating than most gasoline (over 100), allowing for more boost and timing advance without knock. I've even read that it actually releases more power than gasoline when combusted. Compared to water, which doesn't combust at all (and actually replaces some of the oxygen in the cylinder), methanol would definitely make more power. Just thought i'd share. If there are flaws in what i've learned, i'd appreciate criticism! Thanks!

[RICE RACING]

^ massive flaws yes.

The "oxygen" in all alcohol fuels is already USED in the chemical bond of the fuel! it's not adding extra oxygen to the combustion chamber at all, just as E85 fuel does not ......... This is a classic mistake people make. Or what I should say its carrying of "extra oxygen" means its very low on power density and you need to take up more space by throwing in up to double the amount to do the same job you can with proper gasoline! *extra fuel weight* extra pumps, extra injectors....... all cause its an inefficient fuel! This is why it was never used in GP racing after the 30's 40's in supercharged cars, you are always filling them up and they are SLOW as a result, same for air planes not a single one using straight alcohol fuel as its very poor as a total system package. E85 was also scrapped in the 30's after the Govt of the day tried to pull the con on people back then, but people then were smarted and did not buy the rubbish as cars went less distance on it as the power density is worse............ this is true of ALL MAJORITY ALCOHOL FUELS.

The only derived benefit is the extra cooling the alcohol can do to the intake charge (as its power density is far inferior to gasoline or petrol) and you are injecting double the qty of what your would with real fuel. Thus the temperature drop due to vaporization *of double the fuel qty!* is where you get the charge density increase from and its NOT from the extra oxygen in the fuel chemistry its self.

Many efficient engines, make more power on gasoline than they do on any alcohol blended or total fuels, why? cause they can aspirate in more actual air! and its not overtaken by fuel, you need air to burn fuel not more fuel. This is why one a not so rich or near ideal 15% RICH AFR setting you can make more power V's a 20% over stoich RICH fuel setting, you are burning more of the fuel as there is more air and oxygen free to combine with the hydrocarbons in the combustion chamber, AS ALWAYS heat control is your enemy especially in octane sensitive true pump petrol fuels, THIS IS WHY WE USE WATER INJECTION! < It's the most effective way to control temperature and relive maximum heat with minimal loss of volume of power producing air/oxygen. And its the ONLY injectant that can yield MAXIMUM temp reduction in conjunction with MAXIMUM base fuel reduction while still allowing MAXIMUM power production.............. no Alcohol fuel is capable of this be it by internet claim or fact :)

It is only inefficient engines that are knock limited or have poor combustion chamber designs that will benefit from the extra cooling alcohol gives due to needing to run many times more of the stuff due to its inferior power density. So whenever you can throw in more ignition timing to get near the BMEP or use less fuel cooling taking up space of aspirated air then of course you can see marginal gains running the inferior fuels.

Water is a far better way of cooling the engine. AND it allows you to run much less main fuel (and aspirate more air!) which always makes more power! WHY? cause you are using less inferior fuel for cooling the engine internals and aspirating more air which contains free oxygen that takes part in the combustion process and makes more power.

One of the best combination's to make power is gasoline at the right RATIO + Water Injection *again at the right ratio to the main fuel supply* (at a ratio of 50/50 by mass with alcohol). This gives maximum power generation, minimal TOTAL fuel usage, and excellent engine cooling. All other solutions are a net negative for either power generation or vehicular performance. You only need to look at the aviation world where power, speed, reliability and power density to weight are all PRIME OBJECTIVES of internal combustion. You wont see ANY Methanol only fuel planes or Meth injected planes, but you will see base gasoline fueled ones combined with water/methanol injection at 50/50 ratio ;)