Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Carburetor and Oxygen
Name: Michael C.
Status: Other
Age: 40s
Location: N/A
Country: N/A
Date: July 2003

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.

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.


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

Click here to return to the Engineering Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory