There have been numerous
books and plans written purporting to "reveal the secrets" of the
famous "200 mpg carburetor," a device supposedly built in 1935 by
Charles Nelson Pogue of Winnipeg, Canada.
As of this writing Mr. Pogue
is in a nursing home in Winnipeg, Canada. Several of our customers have
visited with him. Each came away with a slightly different story.
Mr. Pogue actually did
manufacture a carburetor he titled the "Winnipeg" in the late 1930s;
317 all told. One of our customers had one and claimed it delivered 35
mpg on a Ford Mustang with considerable loss of power; however, he
agreed to let us have it for testing and we are still waiting.
There are two problems with
the "Pogue principle," which is being touted in high mileage seminars
and books all over the country.
The first is that the Pogue
carburetor violates the first law of thermodynamics, a commonly
accepted scientific postulate that has been with us since 1830.
The law is written as
follows: U = q + w
Or, in simple English, if
you have chemical energy in a system (U) in its expenditure, it must
equal q (heat) plus work (w). That is, if you have 100,000 BTUs in a
gallon of fuel in which you then burn the end products—in a system
operating at 30% efficiency—you will have 30,000 BTUs of work and
70,000 BTUs of heat.
Anything you put inside the
combustion chamber can do only one of two things during the ignition
stroke.
Produce energy
(mechanical movement) during the reaction.
Absorb energy (leave out
the exhaust as heat) during the reaction.
There has been a lot written
about the "unburned particulates" furnishing the extra fuel for the
extra 50 mpg or so, but if you’ll check the Fish dynatune emissions
levels you’ll see there aren’t enough of them to get you another 300
yards down the road.
The second problem
encountered with Pogue-type devices is that—in some instances—they
actually predate the carburetor.
Let’s elaborate in both
cases.
Back before the carburetor
as we know it came into being in the 1890s there were several novel
methods of getting fuel into the engine.
One method was using a
kerosene-soaked rag to drip fuel into the engine.
Another method—that became
quite common—was allowing air to pass over the surface of gasoline and
then to be sucked into the engine. Sometimes a valve—called a "mixing
valve"—would be positioned between the fuel reservoir and the engine.
The valve would pop open when the downward motion of the piston created
enough suction.
This method—and variations
of it—have been touted all over the United States in "100 MPG
CARBURETOR" seminars sponsored by various individuals as being the
"ultimate" in sophisticated fuel systems, usually with exhaust heat or
radiator water added to "vaporize" the fuel much more effectively than
a standard carburetor.
There are a number of things
wrong with the concept of such a "100 MPG" system.
The first is that the
gasolines in use during the days of the mixing valve were far more
volatile than the ones in use today. Some of you may remember when you
could stand ten feet away from an open pan of gasoline, light a match,
and watch the gasoline immediately catch fire.
Gasolines were changed in
the 1930s with the advent of the catalytic cracker now used in
petroleum refining. Carburetors like the Pogue, which depend on easily
vaporized gasoline, simply will not work with today’s gasolines.
The second seminar-taught
error is the method of using exhaust heat or radiator water to heat the
fuel to the "vapor" point to extend the mileage. Warming or preheating
fuel does have some value, but it’s limited.
Consider using hot water
from the radiator to vaporize the fuel first.
Today’s gasolines do not
completely vaporize until they reach 450º Fahrenheit heat, while
the maximum temperature of the water in today’s pressure radiators
reaches only 250º Fahrenheit. You just can’t heat a substance to
450º Fahrenheit using a 250º Fahrenheit heat source.
At least, not on this planet.
Exhaust heat works a bit
differently.
It is the function of an
internal combustion engine to change chemical energy into heat, and
then the heat into mechanical movement. If the heat is not changed into
mechanical movement it simply leaves—as heat. Any time you feel heat
coming off an engine you are feeling wasted energy. The exhaust ports
of an engine that operated at 100% efficiency would be ice-cold to the
touch since ALL the heat would have been changed into mechanical
movement.
Which means that the more
efficient your engine is the less exhaust heat you’re going to have.
For example, if you have
600º Fahrenheit exhaust heat produced by one gallon of gas over a
20-mile trip and you use "exhaust heat" to "vaporize" the fuel and go
60 miles, what produces the 600º Fahrenheit heat for the next 40
miles?
If you answered "two more
gallons of fuel," go to the head of the class!
Seriously, there are ways to
go several times the distance on a gallon of fuel (none of them
involving carburetors); it’s just that the foregoing examples aren’t
two of them.
In short, Charles Nelson
Pogue was a machinist with no formal training in thermodynamics and may
have actually believed that what he was attempting would work.
All a carburetor can do is
meter and atomize fuel in correct proportion to air.
Any further increases have
to come from increasing the thermal efficiency of the engine itself
(such as raising compression) or reducing rolling friction. And this
last is why a diesel locomotive with steel wheels will go ten times as
far on a gallon of fuel as a diesel truck of the same weight with
rubber tires.
For Pogue—or any similar
carburetor—to go 100 mpg on a gallon of fuel on a vehicle normally
going 20 mpg, the air/fuel ratio would have to be in the neighborhood
of 75 to 1 or better.
Any second-year college
chemistry student knows that.
