Quote:
Originally Posted by 1cheap1
So if ethanol is high in oxygen and sucks water out of the air then we would have to keep air out of the fuel tank or keep it to a minimum. Would we have to replace the tank with some sort of soft bladder type tank that would collapse as needed? Or a series of small cells that would keep the air out of the others?
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Yes, you are correct, ethanol is hydroscopic. But since the water links on a molecular level, unlike gasoline where it puddles at the bottom of the tank, it reacts much like water injection would on a gasoline engine. Of course, too much water would definitely cause inefficiency and possible running problems. When ethanol or any alkyl fuel is sold pure it is called 'neat' ethanol or 'neat' methanol. It is considered pure at 95% since it is so difficult to keep it free of water. Only dessicant filters used at the time of operation have been able to get it slightly in excess of 98% pure. Collapsible bladders have been used in the past, but mostly to protect aluminum fuel cells from corrosion because alcohol attacks aluminum. Alcohol is especially agressive when water is present and you burn it. The heated combination creates formic and performic acids during combustion. That is the reason why piston tops in alcohol engines look like they've been sand blasted. Specially formulated oils to be used with neat alcohol are recommended since alcohol attacks conventional oils and has been known to wash cylinder walls and accelerate wear. Ten percent gasoline known as E90 has been proven to nullify the problem; but, E85 became the government standard because oil companies always find a way to keep their hands in the cookie jar and they have the wherewithall to choose the kinds and sizes of cookies.
If one wishes to replace the fuel tank, plastic fuel tanks are available for purchase, and fuel lines that are lined with teflon and butyl are recommended if you don't want to keep changing your rubber hoses every couple of months. Just remember you have to purchase the special AN (Aircraft National) fittings that fit the fuel lines that are made by the same company. EX: Earls, Russels, both companies that make them. I have installed them on all my driven pre-ethanol and classic cars to avoid leaking gas and the constant expense of replacement of rubber hoses.
Neat ethanol produces its greatest energy at 7.0:1 air/fuel ratio where it rivals the btus of energy in gasoline. But who wants to drive a vehicle that gets half the mileage. Neat methanol is even worse at 4.0:1 air/fuel ratio where it produces about 20% more power than gasoline, but the wet volume flowing through the intake runner displaces enough area that intake runners and valves must be enlarged to compensate. That equals an engine specifically designed to run on methanol.
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