frenchyd said:
In reply to AwesomeAuto : why windshield washer fluid? It's only about 10% methanol
The cooling effect of 85% ethanol plus it's 114 octane not only prevents preignition but cools the charge better. Than 10% methanol and water
Not true at all. -20*F windshield washer fluid that is readily available everywhere is 30% methanol, 70% water.
Water cools far better than methanol could ever hope to.
Charge air temps have a lot less to do with preignition and detonation than people think. Methanol does a slightly better job of cooling charge temps because it evaporates more readily than water, but water absorbs twice as much heat energy as methanol when it is converted to gas. It also takes twice as much energy to raise the temperature of water at room temps as it does methanol. Water wins in the cooling department, hands down.
The second problem is that methanol still burns. It might cool charge temps slightly, but its still going to ignite and produce heat. The water will not. Methanol's only benefit here is that its 'slightly' cooler than gasoline. It will still force heat into pistons, it will still cause rings to expand. For guys running cast pistons and tight ring gaps, water wins here too. During compression, the temperature of water is raised high enough that it flashes to steam before ignition. This removes so much heat from the cylinder that it makes detonation or pre-ignition almost impossible. Methanol is still able to detonate in this situation. It will remove some heat, but if it has evaporated, it takes far less energy to raise its temperature, and therefore its still very possible to obtain pre-ignition temperatures during compression.
So for guys running cast pistons that need to stay cool to prevent cracking, and tight ring gaps that need to stay cool to prevent expansion, water beats methanol every time.
If you have forged pistons and preferable ring gaps, methanol is the way to go.
If you are out of fuel injector and need supplemental fuel to make more power, methanol is the way to go.
If you have a wild combo but the CFM flow of your heads isn't up to the task, methanol will cool the charge air better and allow more power for a given port size.
But for pure cooling purposes, water is king.