Air Acetylene Torch

April 24, 2010 | Posted by admin

Air Acetylene Torch

Can someone please answer this theory related to compressed oxygen and the combustion engine?

If the use of a cold air intake modification on a combustion engine in an automobile helps improve power and gas mileage, would introducing a small- med.-lg. amount of compressed oxygen give the same result?
Anyone who’s used an oxy-acetylene torch knows that acetylene alone isn’t capable of cutting anything until you turn on the oxygen.
Is the principle of the cold air intake mod that colder air is denser and since oxygen excites combustian the fuel/air mixture is more volatile?
Why does nitrous oxide boost horsepower so much?
Aside from the obvious modifications needed to introduce oxygen into the air/fuel mixture and possible motor component strengthening, what mods would be required to make this work (if at all), ie.- timing, cam, valves, pistons, compression ratio, etc.?

Combustion of any sort is an oxidation-reduction reaction (“redox” reaction). Hydrocarbons like gasoline and diesel are fuel (reductants). So are acetylene and red-hot iron. Oxygen and nitrous oxide are oxidants.

Think now of the torch flame. It requires a closely-tailored mixture of fuel and oxidant to burn efficiently (hotly). This is operation in the stoichiometric regime. The oxygen blast on the red-hot iron is using iron as a limiting reactant and oxygen in as great excess as possible. It is not necessary to control the fuel-oxidant ratio to burn the iron in this situation.

On the other hand, it is very, very necessary to control the fuel-oxidant ratio in the engine. Notice that we generalize to say fuel-oxidant rather than fuel-air. The about 80% Nitrogen in air does not contribute substantially to the power stroke in the engine cycle. Nitrous oxide cannot be thought of as simply a mixture of nitrogen and oxygen as is air. Being a chemical compound, N2O, its properties are completely different. At room temp, it is essentially inert. Inside the engine, during the burning, it decomposes at temps above 300 deg C, yielding intense reactive oxidants. Thats why it boosts power so much.

Now to answer the questions…
Yes, introducing a small amount of extra O2 in the manifold would increase power as soon as the FI system readjusted itself via the O2 sensor. A medium amount or large amount would stall the engine due to a lean mixture.
Yes, it is the greater density of cold air which the FI system is built to detect and squirt more fuel, making more powerful explosions in the power stroke. The only way the FI system can know that there is a greater O2/N2 ratio is through the O2 sensor. Within limits, it will see that there is excess O2 and adjust somewhat to squirt extra fuel. If the manifold pressure rises due to compressed gas, FI system will see that as more air, not more O2. Unfortunately, a limit is quickly reached where the O2 sensor can’t signal for any more fuel, then you start leaning out too much.

The only good way to do what you want with compressed O2 is reconfigure the FI-system with a custom-programmed chip, not the normal snap-in type. Or, trick the sensor inputs into signalling denser air. Or, extend the duration of the injector pulse over and above what the ECU times out.

Bottom line: Experimenting with small O2 injections will give the result, somewhat of a cold day’s performance. The result will be erratic and will probably set the check-engine light, but will do no harm. To use more O2 requires complicated work, but it is on the order of supercharging as far as principle and damage-potential are concerned. The chief thing to remember is that FI systems are calibrated for air, not O2-enriched air, or nitrous, for that matter. Nitrous is made to work because of the “wet” system you mentioned. Doing that with O2 risks a serious fire. Read over the answer and you’ll understand why.