The liquid fuels we use today were unknown until petroleum or crude oil was first discovered at Titusville, Pa.
in the year 1859. Even then it took more years of experimentation to identify all the useful compounds a gallon of black goo could yield. Texas is at present the largest producer in the
U.S. Some has to be pumped from the ground, some flows freely, or
spurts out in the form of a gusher like an artesian well. Have you wondered how it got there? It is
believed to result from the decomposition of plants and animals
that lived in the sea, which was originally in the areas where it
is found.
While the fermentation process was going, a tremendous build-up of internal pressure caused bulging of the earth’s crust, which in turn formed pockets. The upper parts of these pockets harbor natural gas, still sometimes at great
pressure. It is a thick brownish green oil and as found is a
mixture of Carbon and Hydrogen in varying proportions.
For instance, the formula for cylinder oil is
C23H48, which means 23 parts Carbon in a
chemical mixture with 48 parts Hydrogen. Petroleum and all products
made from it are thus known as hydro-carbons. When properly refined, 100 gallons of crude
oil will normally yield liquid fuels and byproducts in the following measure: about 44 gallons of
gasoline, 6 gallons of kerosene, 36 gallons of fuel oil, 3 gallons
of lubricating oil, and 8 gallons of liquid paraffin wax or asphalt.
While refining is going on the temperature is raised in steps, so
that different byproducts having different boiling points may be
collected separately.
Gasoline, having the lowest boiling point, is collected from 160°
to 390° Fahrenheit temperature. Next in line is Kerosene,
which is boiled off at temperatures from 390° to 570°. And so
on down the line. Lubricating oil is mixed with soaps and various
other compounds to make non-fluid greases. Pennsylvania crude oils
yield paraffin wax and so are said to be paraffin bases. Those from
the west yield asphalt instead and are called asphalt. The formula
for gasoline runs from C7H16, 5.83 pounds per
gallon, containing 122,721 British Thermal (or heat units) per
gallon to C9H20 (for the heavier gasolines)
6.04 lbs per gal., containing 125,450 Btu’s. Kerosene has a
formula of C13H28 weight per gal is 6.82
lbs, and a gallon contains 135,922 Btu. Notice the heavier the
fuel, the more the heat units per gallon. This does not necessarily
mean more power, but instead means more hours of operation on a
tankful, when burned under proper conditions. The heavier the fuel,
the less volatile. The more heat must be used to aid in it’s
vaporization. This heat may be taken from the exhaust pipes and
manifolds of the engine in use and applied to the intake air, as
well as to the mixture after it leaves the carburetor to prevent
condensation within the manifold and so keep in it a state of
vaporization.
Considerable refrigeration goes on right within the carburetor.
You may have noticed the frost that forms next to the carburetor of
a tractor, particularly just after first starting. This is due to
freezing of moisture in the external air brought on by this
refrigeration. No additives in the gasoline will prevent this, they
are merely to keep the moisture in fuel lines from freezing. The
more volatile (more easily vaporized) the fuel the less pronounced
this effect will be. Air by volume, in the country (without smog)
is about 78% Nitrogen (gas which under ordinary conditions will not
unite with any thing else) 21% Oxygen which we need to breathe, and
combines with the hydro-carbons in fuels during combustion also
contains carbon-dioxide, and other trace elements in small
amounts. It takes about 15 lbs of air to burn one lb. of
gasoline. More gasoline is necessary at lower than normal
temperatures. Thus it is necessary to choke a cold motor to start
it.
When burning within a cylinder, the mixture reaches a
temperature around 2,700° Fahrenheit, and carbon-dioxide
(carbon-monoxide in lesser amounts, due to imperfect combustion)
and water are formed, the latter not being noticeable as it is in
the form of steam. It is the expansion of the mixture within the
cylinder due to heating (while burning) which forces the piston
outward and so produces the power. If this burning takes place too
rapidly the piston receives a sledge-hammer blow instead of a more
steady push, and we then have what we call detonation, knocking, or
pinging. This was effectively overcome in years gone by, by feeding
water within the mixture, by means of an extra jet in the
carburetor. This greatly helped to keep the interior of the
cylinders clean and free of carbon also. Kerosene had an octane
rating of zero and made this very necessary.
Modern engines mostly use gasoline, the octane rating depending
on the crude oil it’s made from. The octane rating of untreated
gasoline would be about 60. After the addition of tetra-ethyl
lead and other anti-knock compounds, it can be raised to 100 or so,
Most of the older engines will perform very well on untreated
gasoline. There’s nothing to be gained by burning higher octane gas in them.
The average compression when
they were built was 75 lbs. for gasoline, and 85 lbs. for kerosene
when feeding water. Use the lowest octane gasoline that will give
good performance and you will get the best economy and all around
results.
Years ago we used to hear about oil companies watering their
gasoline. If you believe that just take a small amount of gasoline
and like amount of water, put them in a bottle, shake it up good,
try to mix them and see what happens. You will find them impossible
to mix. In chemistry, it is called non miscible. It used to amuse
me, years ago, to hear some people who had trouble starting their
cars (particularly Model T Fords) tell they were going to get one
of these hot spot manifolds to overcome their difficulty. The heat
from the exhaust would warm the mixture, but there would certainly
be no heat until they got the motor started–quite obviously they
did not understand.
