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I posted a question at a sister site; Why use steam instead of alcohol in Army of Darkness? It is suggested in the comments and an answer that without major modifications the V8 in the Oldsmobile will not run on pure alcohol without blowing up.

Are modifications required to run pure home distilled alcohol in an early 1970s V8? If so what modifications are required?

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Will it run? Yes. Reliably? Depends on what your definition of "reliable" is, as longevity of an otherwise viable vehicle is going to be greatly shortened.

There are several things at play here. There are several problems with running pure alcohol (ethanol) in any vehicle. (Also remember, even ethanol sold as fuel at filling stations is only 85% ethanol and 15% gasoline - on average.) Pure alcohol is corrosive to many parts of the fuel system, especially in older vehicles. It will start corroding the gas tank, which will flake bits of rust into the gas system, start clogging the fuel filter, and eventually cause a leak (over a great period of time). It will also start degrading any seals and rubber hoses associated with the fuel system. I believe newer vehicles which can utilize ethanol based fuels have Teflon seals or stainless steel based tubing to prevent corrosion. It will probably also deteriorate the floats in the carburetor to the point where they will no longer "float" and cause continuous flooding issues.

The next problem is ethanol has less energy per quantity than gasoline, which means your older vehicle will require specific tuning for it. This would require changing jets out in the carburetor to ensure the proper amount of fuel is getting metered. According to this Wikipedia article, 85 ethanol fuel contains about 33% less fuel than regular gasoline. This means you'd need to use a lot more fuel to have the same power output. Timing could be advanced some, since alcohol based fuel has a higher octane rating than petroleum based fuels, making it harder to burn and less prone to pre-detonation (or pinging).

Can a vehicle be made to manage with alcohol based fuels, by all means, but it takes some work to make it happen. Newer vehicles which are "flex-fuel" vehicles (capable of using either regular fuel or E85 fuel) have already made the changes which are needed. They can also measure the fuel with sensors to "understand" what type is being used and adjust how much fuel is being used to cover the changes.

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    So the answer to "modifications required" == "complete replacement of almost anything that touches fuel" ;-) – Bob Cross Mar 21 '14 at 13:20

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