"Rimington, Ken" wrote:
> My neighbor has a strange ides. He recommended using a moth ball in a tank
> of unleaded as an octane booster to prevent pre-ignition knocking. Has
> anyone heard of this before? Is it a good idea?
>From Click & Clack,
http://cartalk.cars.com/Columns/CC/CC7046TXT.html
Dear Tom and Ray:
I have been told that
adding seven or eight
naphthalene mothballs to a tank
of gasoline increases the octane.
Is this true? If it is true, what will
it do to the engine of the vehicle?
-- Donald
Ray: That's an excellent question, Donald. This "mothball" story has
been around as long as we have. So immediately upon receiving your
letter, we called in the illustrious Dr. Jim Davis, Ph.D., director of the
chemistry labs here at Car Talk Plaza, to try to get a definitive answer.
And Jim said he'd get right on it.
Tom: Two months later, he called us and apologized for the delay,
which he said was unavoidable due to a two-month-long faculty
meeting that had just ended at Harvard, where he moonlights.
Ray: Anyway, after several months of study, and the complete
depletion of an otherwise useful NIH grant, Jim has concluded that this
mothball story is basically a bunch of horse pie.
Tom: There are several different types of mothballs on the market,
none of which, to his knowledge, do anything to improve the
performance of gasoline. They WILL burn, so you will get some
power out of them. But since mothballs are more expensive than
gasoline, this is not a very economical way to get to work, Donald.
Ray: If there were some magical performance-enhancing mothball,
Jim says, don't you think Exxon and Mobil would be selling it to us as
an expensive gasoline additive i.e. "Mobil Super ... Now with
Mothballs!"
Tom: The kind of mothball you mention, Donald, is made of
"naphthalene" which is a hydrocarbon, like gasoline. For those
chemical engineers reading today, it's C10H8, and it looks like two
benzene rings fused together. Jim says that benzene makes a very
smoky fire when burned, so his guess is that naphthalene would make
a lousy gasoline. On the other hand, he says, since it's just carbon and
hydrogen (like gasoline) naphthalene probably wouldn't do any harm to
the engine either.
Ray: Another type of mothball which COULD potentially hurt things
is made of dichlorobenzene. That won't improve your car's
performance either, but since it throws chlorine into the mix, it can
produce HCl as a byproduct when burned.
Tom: For those of you who don't remember your high school
chemistry, HCl is hydrochloric acid, the stuff that burns through almost
anything it touches. And pumping HCl through your engine and
exhaust system is probably not very good for its longevity, Donald.
Ray: Not to mention what it does to a) the people who happen to be
breathing anywhere near the end of that exhaust system, b) your
catalytic converter, and c) your manufacturer's warranty.
Tom: So, based upon Jim's
research, we feel confident in
summarily dismissing the notion
that adding mothballs to your gas
tank does anything to improve
performance.
Ray: The only thing Jim will guarantee is that, if you put mothballs in
your gas tank, any sweaters you store in there will come out without
moth holes in them.
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