PART TWO: FUEL SYSTEMS
alcohol). Methanol or methyl alcohol (CH 3 OH) is termed “wood alcohol” because origi-
nally it was distilled from wood. Rubbing alcohol (C 3 H 8 O) is used to rub sore muscles and
as a medical disinfectant, an antifreeze, a solvent, and many other things. Neither methanol
or rubbing alcohol is currently used in a mixture with gasoline as fuel, and both are poisons
if ingested. Note that ethanol is also occasionally used as a rubbing alcohol.
Existing cars, trucks, and boats almost universally operate on gasoline or diesel fuel—both
of which are petroleum products. Diesel engines—due to the way diesel engines function—
can’t burn alcohol in any form; however, almost all gasoline engines can safely run on the
appropriate mixture of gasoline and ethyl alcohol. In this use, it’s the mixture of gasoline and
ethyl alcohol that’s generally termed ethanol.
The role ethyl alcohol plays when mixed with gasoline is complex. It isn’t simply burned, but
it replaces MTBE (methyl tertbutyl ether), which in turn replaced tetraethyl lead to reduce lead
emissions. The purpose of these various additives is primarily to increase the oxygen level in
the fuel and so increase performance and reduce knocking—increasing octane level. Such
additives are thus oxygenates.Advantages of Ethanol
The alcohol in ethanol burns cleanly with low exhaust emissions, and it helps the gasoline burn
more efficiently. As we’ve seen, ethyl alcohol is also renewable, and so—taken all together—
it appears to be a green or environmentally friendly energy source. There is, however, some
debate about the net gains from using ethyl alcohol to make ethanol gasoline. It can be argued
that the energy required to produce and transport the raw material, distill it into ethyl alcohol,
and properly blend it with gasoline—along with other practical factors—make the environ-
mental gains less impressive or possibly a net loss.Ethanol Fuel Mandates: The New Development
Regardless of any controversy that may exist about the merits of ethanol gasoline for the en-
vironment or for the economy, many states and the U.S. Congress have mandated ethanol’s
use as a fuel. In fact—since almost all gasoline engines can run well on gasoline with 10 per-
cent ethyl alcohol blended in—such fuel is, all of a sudden, common. The concept of ethanol,
however, has been around for decades and has been used as an actual fuel in quite limited
distribution since the late 1970s. Until the recent legal mandates, though, ethanol was rare.
Since 2006, it has become widespread.
Ten percent ethanol (the blend of 10 percent ethyl alcohol by volume and gasoline) is
called E10, for ethyl alcohol 10 percent. E20 is a blend with 20 percent alcohol. E85 is 85 per-
cent ethanol and 15 percent gasoline. It works well in gasoline engines, but only in engines
and fuel systems specifically prepared to use it. In any case, the higher percentage blends are
(as of 2006) less common because they are more likely to cause problems when used in exist-
ing, unmodified gasoline engines and fuel systems.Ethanol Degrades Fiberglass Tanks
All of the preceding has led to a rather new (in 2006) and largely unforeseen problem with
fiberglass gasoline fuel tanks. A spate of tank and fuel difficulties have developed. After
research and testing arranged by BoatU.S. and several marine surveyors dealing with odd fuel-
system failures, these problems have been traced back to the alcohol in ethanol gasoline
reacting with and dissolving the resin in fiberglass fuel tank walls. The process is chemically(Continued from previous)