Date: Mon, 7 Nov 1994 21:59:54 -0800 (PST)
Sender: Vanagon Mailing List <vanagon@vanagon.com>
From: H Steven Dolan <dworkin@netcom.com>
Subject: Re: Ethanol
On Mon, 7 Nov 1994, David Carment wrote:
> OK dumb question why don't we run diesel in our engines? If its is more
> efficient and cleaner then we should all do the diesel thing. (it is used
> to be a whole lot cheaper too). Or is gas somehow designed to be an
> optimal fuel for other (more conspiratorial) reasons.... --
No conspiracy. First off, diesel is definitely NOT cleaner, as any of the
tailgaters in the recent thread can tell you. In addition, while BTU/lb
is very important, a factor called "flash point" is also vital. Alcohols,
despite (or perhaps because of) their lower BTU value evaporate and burn
at even lower temps/pressures than gasoline. Diesel fuel doesn't. Your
standard gas engine is actually a high precision instrument that mixes
fuel, air, and spark in very precise amounts at very precise times. The
standard vacuum on a carb won't even pull diesel, it's too thick. While a
fuel injector might force it into a cylinder, it won't evaporate fast
enough to be a good fuel/air mix when the spark goes off. So, no go on
running diesel fuel thru your gas engine (except as a cleaner and even
then it looks like you forgot to install your piston rings because the
fuel/air mix is AFU). The high compression in a diesel engine not only
raises the temp in the cylinder high enough to ignite the diesel/air mix,
it raises the temp high enough (previous to the ignition point) to
evaporate the (relatively thick) diesel fuel in the combustion air.
Anyone who wants the gorey details, I can supply them, but in essence:
Gas works best in cars designed for gas.
(use the lowest octane rated gas you can, as all
gasoline has the same BTU/lb)
but oxygenated fuels {w/ethanol/MBTE/etc.} *may*
reduce the amount of pollutants your car spews
Diesel works only for diesel (or cleaning your engine)
The full bore/no pollution/low cost/high mileage solution is to convert
your engine to LPG (run your engine off your reefer), but initial
cost/fuel availability is a real problem. LPG has a high BTU/lb ratio,
burns very cleanly, and you can generally avoid the road taxes on
automotive fuels. On the other hand, conversion can cost 1-2 thousand
US$, and fueling at 3AM is a real problem (try to find an open camp
ground/hardware store, in January, in Canada).
H Steven Dolan
dworkin@netcom.com
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