Merits of water in a mainly methanol mixture?.

[JohnA]

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: