Re: DRY GAS (fuel additive ?)

["Christopher M. Smith" <csmith@sdsc.edu>]

On Wed, 3 Dec 1997, Toby Erkson wrote:

> Well, I know from experience that fuel additives meant to remove water from 
> the tank work.  My Dad and I call 'em "gas dryers" so I don't know what the 
> approved term is, but they contain alcohol and it mixes with the water in 
> the tank.  This allows the engine to keep running (although, maybe poorly) 
> while it's "burning" the water.  Normally, when the engine gets a bubble of 

"Dry Gas" (aka, Methanol, wood alcohol) is nothing more than high-grade
(%) alcohol. "Octane Booster" is essentially the same thing as well.
Short-chain [carbon] alcohols are non-polar (like gasoline), but are
somewhat miscible (unlike gasoline) with polar agents (i.e., water). In
fact absolutely pure alcohol (100%, 200 proof) is what we call hydroscopic
... it loves water and will absorb it whenever it is in it's presence. 
Alcohol itself is flammable (burns), even when it's hydrated with a bit of
water. 

So what happens in your gas tank is water is absorbed into the alcohol,
which mixes with the gasoline, and both are combusted in your cylinders.
The amount of water in the alcohol that is in your cyclinders at any given
stroke is negligible, therefore it has very little if any effect on
combustion. Without the alcohol "carrier", water that has condensed in 
your gas tank (cold climates) makes it's way to your engine and may be
injected, in whole, into the cylinders. Instead of combustible gasoline
vapour in your cylinders, you get non-combustible water vapour. The result
is a "miss" or series of "misses" (sputtering). In extremely bad
situations your engine dies altogether (or will not start/restart).

Water in the gas tank is relatively easy to diagnose in a VW. If you
encounter sputtering from your beloved VW while driving up or down steep
gardes, but a fine tune while driving on level grades, and/or you've got
from a warm climate to a cold one, then you've probably have water in the
tank.

Chris
San Diego
73' T3 (216K miles, original owner and love it!)