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    Cooling Power of Meth versus Water

    I'm curious about Meth versus water's cooling ability. I have noticed that larger concentration of Meth definitely cools better as far as IAT's read at the throttle body. My thought is that Meth evaporates faster and thus more cooling before the TMAP sensor. But once water fully evaporates it should have better cooling properties CORRECT? An additional thought is that potentially some of the water may not fully evaporate until compression, combustion.

    Any thoughts on this?

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    Interesting topic and usually debated as to whether meth or water have a better cooling impact. Which is why the % of each in the mixture is also debated.

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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    I'm curious about Meth versus water's cooling ability. I have noticed that larger concentration of Meth definitely cools better as far as IAT's read at the throttle body. My thought is that Meth evaporates faster and thus more cooling before the TMAP sensor. But once water fully evaporates it should have better cooling properties CORRECT? An additional thought is that potentially some of the water may not fully evaporate until compression, combustion.

    Any thoughts on this?
    That must be true. It takes more energy to evaporate water, but it ultimately will. So it will cool the charge more than methanol. On the other hand, you can always spray more methanol to compensate for the lesser cooling.

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    Doesn't methanol's thermodynamic properties allow it to dissipate more heat than water?

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    Debating whether to post.....

    Do I have the time for this topic?
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    ^please do, although who am i to ask... Click here to enlarge
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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    I'm curious about Meth versus water's cooling ability. I have noticed that larger concentration of Meth definitely cools better as far as IAT's read at the throttle body. My thought is that Meth evaporates faster and thus more cooling before the TMAP sensor. But once water fully evaporates it should have better cooling properties CORRECT? An additional thought is that potentially some of the water may not fully evaporate until compression, combustion.

    Any thoughts on this?
    Some fluid makes it in to combustion and thus lowers the resulting cylinder temperatures, reduces EGT, and helps stabilize combustion. Too much water causes problems though. Methanol/alky will evaporate faster, often in the charge pipe, which is reflected in those IAT thermistor readings. As you expected the IAT reading is just one sensor in one location and does not tell the entire story.

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    I assume you guys never listened to the chemistry teacher lol.

    specific heat capacity of Water: 4184 J/Kg
    specific heat capacity of Metahnol: 2545 J/Kg

    If you didn't understand what it means, it means water has better cooling power.

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    Yes but its not an easy answer to which to use. It depends on what EXACTLY ur spraying meth/water for. It's a balance as more intelligent people above me have said. Water alone will cool better in theory, but how much can u spray, how much is too much. Do u want octane as well? EGT and cyl. temps were mentioned as well..
    Waiting for more intricate and elaborate explanations though Click here to enlarge

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    Click here to enlarge Originally Posted by Sorena Click here to enlarge
    I assume you guys never listened to the chemistry teacher lol.

    specific heat capacity of Water: 4184 J/Kg
    specific heat capacity of Metahnol: 2545 J/Kg

    If you didn't understand what it means, it means water has better cooling power.
    Yes, in theory, water has infinite octane because unlike meth it won't combust.

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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Yes, in theory, water has infinite octane because unlike meth it won't combust.
    Yes, but water doesn't ADD octane, it is just non-combustible... actually taking up space and reducing the total combustion energy, but increasing dynamic compression.

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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    Yes, but water doesn't ADD octane, it is just non-combustible... actually taking up space and reducing the total combustion energy, but increasing dynamic compression.
    It's tough to try to figure out how to phrase it exactly. In essence, it does add octane because it is making it more difficult to combust.

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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    Yes, but water doesn't ADD octane, it is just non-combustible... actually taking up space and reducing the total combustion energy, but increasing dynamic compression.
    I'm with Sticky on this one. Although water has no actual octane it does infinity raise the octane rating. Click here to enlarge

    Don't confuse adding octane with adding horsepower though.

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    I think you all are looking at this wrong. Water cannot combust, BUT it is not increasing the A/F mixture’s resistance to spontaneous combustion. Meth has a higher octane (but also contributes to combustion energy) and thus due to the percentage of meth and gasoline the A/F mixture has higher ignite temperature. Water will reduce the A/F mixture’s temperature and effectively reduce the cylinder’s volume, but will NOT change the fuel’s ignition temp. Anyway, that’s how I look at it but I’m not an engineer.

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    You're just confusing octane with octane rating. Anyway, we all knew what you meant. Click here to enlarge

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    Ok.

    Although water has a high heat of vaporization (takes more heat for it to turn into vapor form) it can absorb a lot of ambient heat before it changes phase. One would think that because of this water would make a better liquid intercooler. Here is the problem, water is less volatile than methanol. Methanol becomes gaseous very quickly, so although on a PER MASS basis methanol absorbs less energy upon vaporization, the methanol readily vaporizes much much faster and is thus the better liquid for air cooling.

    Not to mention the added octane benefits of methanol. But the question was asked which is the better liquid intercooler, that would go to methanol due to the sheer fact that it has much less surface tension than water and will vaporize nearly instantly with the above mentioned benefits.

    I was going to add something more.

    Have you ever spilled methanol all over your hands? I have, and before I can wipe it off the methanol is gone, completely gaseous and in the process sucks the heat right out of your hand. Thats why your hand feels like it was in a freezer right after getting hit with some meth. Water does this too, but because it wont evaporate as quickly, you dont feel the same effect.

    Eventually, if you stand there long enough and spilled the SAME AMOUNT of water on your hand under the same conditions, it would have removed more heat from your hand. But because your hand can generate heat faster than the water can remove it, you wont feel as cold as you would with methanol hitting your skin. The methanol literally sucks heat out very quickly upon vaporization, the technical term for this is latent heat of vaporization and there is more to intercooling by looking solely at this property.
    Last edited by DBFIU; 09-20-2011 at 07:52 PM.
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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    Meth has a higher octane
    Impossible considering water does not combust.

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    I have done a decent amount of testing but with less focus on IAT and more focus on ignition. I have found that my timing picks up significantly with higher meth concentration mixtures while IATs still decrease significantly. I am basically running 100% meth now.
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    Click here to enlarge Originally Posted by Sticky Click here to enlarge
    Impossible considering water does not combust.
    geez you're nitpicky when you think you know something... i meant higher octane then gasoline so it raising the octane rating of total fuel, or ignitable compounds... water does not contribute here and the infinite octane only relates to itself and doesn't effect octane rating of the mixture.

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    Click here to enlarge Originally Posted by JoshBoody Click here to enlarge
    geez you're nitpicky when you think you know something... i meant higher octane then gasoline so it raising the octane rating of total fuel, or ignitable compounds... water does not contribute here and the infinite octane only relates to itself and doesn't effect octane rating of the mixture.
    Not trying to nitpick you at all simply saying an object that does not combust in theory always has higher octane because there is no way to rate it since it is infinite.

    Why does not it not relate to the octane rating of the mixture if it makes it resist combustion?

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    Click here to enlarge Originally Posted by Irishace Click here to enlarge
    I have done a decent amount of testing but with less focus on IAT and more focus on ignition. I have found that my timing picks up significantly with higher meth concentration mixtures while IATs still decrease significantly. I am basically running 100% meth now.
    There are trade offs. I suggest keeping some water in the mix to help cool down combustion. Especially on pump gas. 80/20 is good. But close to 100% with race gas is OK for track days. Just keep that fire extinguisher close by. Click here to enlarge

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    Click here to enlarge Originally Posted by LostMarine Click here to enlarge
    Yes but its not an easy answer to which to use. It depends on what EXACTLY ur spraying meth/water for. It's a balance as more intelligent people above me have said. Water alone will cool better in theory, but how much can u spray, how much is too much. Do u want octane as well? EGT and cyl. temps were mentioned as well..
    Waiting for more intricate and elaborate explanations though Click here to enlarge
    Yes, but we are not talking about " which is better to cool down ", we are talking about " which has better cooling power ".
    even if we are talking about " which is better too cool down " IMO water is better. IMO the two problems with water are these:

    - higher volumetric expansion coefficient. it means in the same condition, if we give X amount of heat to both fluids, the volume of
    water will expand twice as methanol. in other words, if we fill a radiator with water, we have to fill it less compared to methanol.

    - Water is an oxidizer. methanol can be too, but not in every condition.

    and hey, i found that statement offensive. lol

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    I don't understand why people give water an infinate octane rating when octane rating (regarding to engines) is given to fuels. Being that water is not a fuel, it is sort of useless.

    Over the past 5-6 years on multiple car I came to the same conclusion. You want the best power, 100% meth. You want slightly cooler temps in the chamber, mix 20-30 percent water to your meth mix, however with the n54, will have to drop the tune a tad.

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    Click here to enlarge Originally Posted by Sorena Click here to enlarge
    Yes, but we are not talking about " which is better to cool down ", we are talking about " which has better cooling power ".
    even if we are talking about " which is better too cool down " IMO water is better. IMO the two problems with water are these:

    - higher volumetric expansion coefficient. it means in the same condition, if we give X amount of heat to both fluids, the volume of
    water will expand twice as methanol. in other words, if we fill a radiator with water, we have to fill it less compared to methanol.

    - Water is an oxidizer. methanol can be too, but not in every condition.

    and hey, i found that statement offensive. lol
    But its a double question. Overall water cools better, but needs more time to do so, which is the constraint. So given the time.considerations, meth is better, because it does it faster

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    2 out of 2 members liked this post. Yes Reputation No
    And I found some time.

    Whether you are injecting meth, gasoline, or water, there are a range of areas that can be affected:
    • Burn speed
    • Cylinder temps
    • Peak cylinder pressure timing (crank angle)
    • Air density
    I wouldn't say that injecting water changes the fuel's octane rating, but it does change how the engine interacts with fuel making similar results to higher octane being used. There is a difference though. Where higher octane affects burn speed the most, adding water primarily affects cylinder temps, and by extension peak cylinder pressure timing. So the slower burn speed of a higher octane fuel will arrive at X degrees PCP, the water changes the PCP by starting at a lower cylinder temp/pressure, and the rise time of cylinder pressure is actually faster than high octane fuel, but they arrive at the PCP at the same cranking degree.

    Meth affects both burn speed and cylinder temps a high degree, so it has a compound effect on PCP.

    The goal is to have minimal pressure before TDC, as this takes power away from the engine. This is a big part of why advancing the timing closer to TDC makes more power. So adding water starts the burn temp/pressure at a lower level, and the engine sees less resistance before TDC. Adding meth does this as well, but it also slows the burn speed so that more of the mass fraction is burned after TDC.

    So that's what is going on in the cylinder. We obviously missed one point, and that's Air density.

    Before the combustion cylinder this is where we seem to be focused on "cooling" the air charge with meth or water, or both. I think which one is better is more dependent on the hardware being used than the injection medium. A poor injection nozzle is going to perform better with meth than water, and a great nozzle will work better with water. Big area of discussion and experimentation for sure.

    Then there's pre-turbo injection, which targets something entirely else...although nobody seems to be able to quantify what that is. LOL


    If anyone is looking for the "mother" of all Water/Meth injection threads, it can be found in the link below. Admittedly, the topic is pre-turbo injection, but the theory and technical discussion applies to post-turbo injection as well.

    http://www.aquamist.co.uk/vbulletin/showthread.php?t=251



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