6.20 Can mothballs increase octane?
Description
This article is from the Gasoline FAQ, by Bruce Hamilton with numerous contributions by others.
6.20 Can mothballs increase octane?
The legend of mothballs as an octane enhancer arose well before WWII
when naphthalene was used as the active ingredient. Today, the
majority of mothballs use para-dichlorobenzene in place of
naphthalene, so choose carefully if you wish to experiment :-). There
have been some concerns about the toxicity of para-dichlorobenzene,
and naphthalene mothballs have again become popular. In the 1920s,
typical gasoline octane ratings were 40-60 [11], and during the 1930s
and 40s, the ratings increased by approximately 20 units as alkyl
leads and improved refining processes became widespread [12].
Naphthalene has a blending motor octane number of 90 [52], so the
addition of a significant amount of mothballs could increase the
octane, and they were soluble in gasoline. The amount usually required
to appreciably increase the octane also had some adverse effects. The
most obvious was due to the high melting point ( 80C ), when the fuel
evaporated the naphthalene would precipitate out, blocking jets and
filters. With modern gasolines, naphthalene is more likely to reduce
the octane rating, and the amount required for low octane fuels will
also create operational and emissions problems.
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