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Old 07-12-2007, 11:20 PM
keithmac keithmac is offline
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Default Merits of water in a mainly methanol mixture?.

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.
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Old 15-12-2007, 09:10 AM
JohnA JohnA is offline
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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.
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Old 17-12-2007, 04:09 PM
keithmac keithmac is offline
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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..
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Old 17-12-2007, 06:42 PM
JohnA JohnA is offline
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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:
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Old 12-05-2008, 01:40 PM
dudical26 dudical26 is offline
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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.
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Old 28-05-2008, 07:07 PM
JohnA JohnA is offline
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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.
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Old 06-02-2009, 06:22 PM
djuosnteisn djuosnteisn is offline
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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!)
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Old 06-02-2009, 06:55 PM
JohnA JohnA is offline
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Quote:
Originally Posted by 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!)
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:
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Old 06-02-2009, 07:28 PM
djuosnteisn djuosnteisn is offline
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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.
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Old 06-02-2009, 07:47 PM
djuosnteisn djuosnteisn is offline
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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?
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