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Carburetor and Oxygen
Name: Michael C.
Status: Other
Age: 40s
Location: N/A
Country: N/A
Date: July 2003
Question:
I read the question about using ionized air in an automobile carburetor. This
brings me to wonder, what would happen if small quantities of pure oxygen were introduced
into the carburetor, or fuel injection system. Wouldn't this result in more complete combustion
of the fuel? This has puzzled me for some time, so any response would be very appreciated.
Replies:
The burning of gasoline is a little more complicated than just adding oxygen. In order for a set
amount of gasoline to burn completely, a set amount of oxygen is needed. Any amount less than that
results in incomplete combustion of the gas and too much leads to excess oxygen in the exhaust,
which doesn't sound bad if gasoline was just pure gasoline. However, you cannot purchase pure
gasoline. Refining of oil into gasoline leaves impurities (like sulfur) in the gas because oil
contains impurities in the first place. You could argue that we need purer gas, but the cost
would probably upset you local SUV driver. So, when excess oxygen is in the exhaust at such
high temperature, it reacts with the impurities that can lead to oxides, like sulfur dioxide.
When sulfur dioxide gets into the air and sunlight hits it, it turns into smog. Another issue
is that the air that is feed into your engine also contains other things beside oxygen, mainly
nitrogen. Again at high temperatures, nitrous oxides are created due to excess oxygen hanging
around. But what engine manufactures have done is place sensors in you car to monitor many of
the variables in combustion to optimize the fuel consumption. That is why you have seen more
fuel efficient cars without the loss of horsepower over the years (but we still need to do
better :-)). Sensors monitor your air intake, fuel feed rate, exhaust, temperature, etc. to
optimize all variables for the best combustion.
Hopefully this helped answer why just adding pure oxygen is not the complete answer.
Regards,
Christopher Murphy, P.E.
The firing of an automobile engine is not instantaneous. The rate of combustion needs to be
controlled so that explosion does not occur prematurely. That results in "pinging" or more
correctly pre-ignition. Normally the fuel/air mix is adjusted so that the ignition is
"smooth". One could design an engine that used pure oxygen, but that would be a major
re-design.
Vince Calder
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