Pure Water - pure Meth - Mix? Ethanol?
03-03-2009, 07:07 AM
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Pure Water - pure Meth - Mix? Ethanol?
I started to learn more about WI a few weeks ago - the technics/ application behind it is clear, but I'm still unsure about WHAT to spray...
From what I've read WATER is good for a cooling effekt during the combustion cycle, METHANOL is better at chargecooling the hot Air in the intake... is that true?
So what would be the best option for a Coldside supercharger at 200whp (stock internals, 9,5:1 )?
Pure water - maybe even with a direct port injection?
Meth/ Meth blend, but more located towards the blower outlet?
Or could I even use an Ethanol Blend (Meth is hard to get here in Germany, no Meth in Washer fluid, not allowed to be sold to "normal" people...
I'm running the car with E85, does this make a difference wether to use plain water or a meth blend?
Thankx for your answers
From what I've read WATER is good for a cooling effekt during the combustion cycle, METHANOL is better at chargecooling the hot Air in the intake... is that true?
So what would be the best option for a Coldside supercharger at 200whp (stock internals, 9,5:1 )?
Pure water - maybe even with a direct port injection?
Meth/ Meth blend, but more located towards the blower outlet?
Or could I even use an Ethanol Blend (Meth is hard to get here in Germany, no Meth in Washer fluid, not allowed to be sold to "normal" people...
I'm running the car with E85, does this make a difference wether to use plain water or a meth blend?
Thankx for your answers
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03-03-2009, 05:04 PM
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Disclaimer: I am not a chemist, and I have little scientific knowledge of this subject.
My understanding is that methanol is used largely because is it combustible (whereas water is not) and that it has a very high octane rating (114).
The specific heat capacity of water (it's ability to absorb heat from its surroundings) is much higher than methanol; 4.18 KiloJoules/KiloGram/°C at 25°C as compared to 1.45 KJ/KG/°C. What this means is that a given mass of water can absorb roughly three times as much heat energy from its surroundings than methanol, regardless of where this absorption takes place (in the intake tract vs. in the cylinder).
The enthalpy of vaporization of methanol is about half that of water, meaning it's more likely to transform from a liquid to a gas inside the intake pipes, so perhaps that's where the assumption you posit comes from.
Of course, this is all a lot of theory with no application.
From a practical standpoint, I run a mixture of roughly 50% water and 50% methanol. I purchase my methanol from a supplier of racing fuel in 5 gallon quantities, and each five gallon bottle lasts quite a while.
Why do I run 50/50? Probably because I read that a bunch of other people do also.
With regard to nozzle placement- if you are running an intercooler, the nozzle should be placed after the intercooler. Injecting water prior to an intercooler will pre-cool the air and prevent the intercooler from doing its job.
My understanding is that methanol is used largely because is it combustible (whereas water is not) and that it has a very high octane rating (114).
The specific heat capacity of water (it's ability to absorb heat from its surroundings) is much higher than methanol; 4.18 KiloJoules/KiloGram/°C at 25°C as compared to 1.45 KJ/KG/°C. What this means is that a given mass of water can absorb roughly three times as much heat energy from its surroundings than methanol, regardless of where this absorption takes place (in the intake tract vs. in the cylinder).
The enthalpy of vaporization of methanol is about half that of water, meaning it's more likely to transform from a liquid to a gas inside the intake pipes, so perhaps that's where the assumption you posit comes from.
Of course, this is all a lot of theory with no application.
From a practical standpoint, I run a mixture of roughly 50% water and 50% methanol. I purchase my methanol from a supplier of racing fuel in 5 gallon quantities, and each five gallon bottle lasts quite a while.
Why do I run 50/50? Probably because I read that a bunch of other people do also.
With regard to nozzle placement- if you are running an intercooler, the nozzle should be placed after the intercooler. Injecting water prior to an intercooler will pre-cool the air and prevent the intercooler from doing its job.
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