# Oxygen tanks on cars
**URL:** https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370
**Category:** Factual Questions
**Created:** [November 23, 2002, 7:18pm UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370 "2002-11-23T19:18:28Z")
**Posts on this page:** 13
**Page:** 1
### Author:  [@Squink](https://boards.straightdope.com/u/Squink)
#### Post date: [November 23, 2002, 7:18pm UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/1 "2002-11-23T19:18:28Z")
The recent threads on [Hydrogen Power Production](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=145280) and [Superchargers](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=144581) got me to wondering if anyone has tried hooking up an oxygen tank to the air intake of their automobile. The resulting higher burn temperature, and possibility of igniting a lot more fuel per piston stroke, should increase efficiency, while giving the engine’s horsepower rating quite a kick. The setup would also be mechanically simpler than a turbocharger or supercharger. I’m sure that such a modification would be dangerous, and shorten a stock engine’s useable lifetime, but would it also be illegal ?
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### Author:  [@Ringo](https://boards.straightdope.com/u/Ringo)
#### Post date: [November 23, 2002, 7:36pm UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/2 "2002-11-23T19:36:51Z")
That sounds similar to what people accomplish with [nitrous oxide](http://www.chm.bris.ac.uk/motm/n2o/n2oc.htm) systems. From the link:
> [@](#):
>
> At room temperature, N[sub]2[/sub]O is quite unreactive with most substances, including alkali metals, halogens, and even ozone. It is therefore widely used as a propellant in aerosol cans in place of the CFCs which can damage the ozone layer. When heated sufficiently, however, N2O decomposes exothermically to N[sub]2[/sub] and O[sub]2[/sub].
>
> If this reaction occurs in the combustion chamber of an automobile, 3 moles of gas would be produced from 2 moles, providing an extra boost to the piston, as well as liberating more heat. It also has a number of other benefits. The increased oxygen provides more efficient combustion of fuel, the nitrogen buffers the increased cylinder pressure controlling the combustion, and the latent heat of vaporisation of the N[sub]2[/sub]O reduces the intake temperature. Therefore N[sub]2[/sub]O is occasionally injected into the fuel lines of racing cars to give more power to the engine and to give the car exceptional acceleration.
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### Author:  [@Ringo](https://boards.straightdope.com/u/Ringo)
#### Post date: [November 23, 2002, 7:50pm UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/3 "2002-11-23T19:50:25Z")
If I’m reading correctly, the combustion of the gasoline provides the heat that allows the N[sub]2[/sub]O decomposition, increasing the effective compression ratio and giving a more efficient reaction\*. So, not exactly what you’re proposing with just oxygen, but along the same lines.
\*[sub]caveat - this comes from a person who liked organic chem so much that he took it over again.[/sub] 😉
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### Author:  [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)
#### Post date: [November 23, 2002, 8:09pm UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/4 "2002-11-23T20:09:30Z")
They tried pure O2 before NO2…with disasterous results: the engine exploded.
With NO2 in the combustion chamber during ignition, the Oxygen dissociates from the Nitrogen; the Nitrogen acts as a buffer, slowing the combustion process and prevents pistons and valves from burning.
This is with spark ignition engines…I don’t know how a diesel would react to a pure Oxygen atmosphere.
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### Author:  [@ftg](https://boards.straightdope.com/u/ftg)
#### Post date: [November 23, 2002, 10:31pm UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/5 "2002-11-23T22:31:09Z")
Note that pure O2 reacts with just about anything (including concrete) given the slightest bit of a nudge. I strongly suspect that the extra O2 in a fuel system would start the combustion well before the max. compression is achieved. This is not a good thing. Keeping a cylinder from firing too soon is one of the major issues in engine design. Note that N20 is somewhat inert at room temps and takes quite a bit of zap to get it to break down, hence it is not too much of an issue in this way.
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### Author:  [@Squink](https://boards.straightdope.com/u/Squink)
#### Post date: [November 23, 2002, 11:21pm UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/6 "2002-11-23T23:21:34Z")
Pure O[sub]2[/sub] would certainly cause problems, but I’m thinking that with modern microprocessor controlled gas mixers it might be possible to up the intake gas from the normal 20% O[sub]2[/sub] to say 30 or 40%. You’d end up with the same amount of Oxygen per cylinder as if you had used a supercharger to double the compression, but without the pressure, and consequent heating during the compression stroke. That _might_ be enough to reduce premature firing.
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### Author:  [@andy\_fl](https://boards.straightdope.com/u/andy_fl)
#### Post date: [November 23, 2002, 11:49pm UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/7 "2002-11-23T23:49:35Z")
> [@](#):
>
> \*Originally posted by Squink \*
> \*\*got me to wondering if anyone has tried hooking up an oxygen tank to the air intake of their automobile. The resulting higher burn temperature, and possibility of igniting a lot more fuel per piston stroke, should increase efficiency, while giving the engine’s horsepower rating quite a kick. The setup would also be mechanically simpler than a turbocharger or supercharger. I’m sure that such a modification would be dangerous, and shorten a stock engine’s useable lifetime, but would it also be illegal ? \*\*
First of pure Oxygen is very dangerous to work with. All parts which can come in contact with Oxygen need to be oxygen cleaned before use. So any grease left behind may probably cause an explosion. Also, if you are planning to carry around the regular compressed oxygen bottles, it may be illegal due to DOT laws.
Having said that - using pure Oxygen rather than air will have a lot of advantages as you correctly point out. Following will be the disadvantages:
1\> Air to fuel ratio used commonly is around 15:1 (by mass) [from here](http://courses.washington.edu/me341/oct22v2.htm). Now air contains around 21% (by volume 23% by weight) oxygen so if you used pure oxygen, the oxygen to fuel ratio will be around 3.5:1. Now density of gasoline is around 6 lb/gal, so for every gallon of gas you will need around 21 lbs of oxygen! So everytime you fill up say around 16 gallons of gas, you’ll have to take another 336 lbs of Oxygen and that is just the weight of Oxygen - Including the weight of the cylinder will almost double it.
2\> Cost of oxygen is around $20/ 200 scf, for Industrial grade. Density of oxygen at standard conditions is around 0.09 lb/cf. So you’ll have to pay around a $1 per pound of industrial grade oxygen. So you’ll have to cough up $3.5 more per gallon of gas. ( This price calculation is approximate)
3\> Nitrogen oxides formation is a strong function of temperature and availability of excess oxygen beyond that required by stoichiometry. Since you’ll be running at a higher temperature and with industrial grade oxygen (which has nitrogen), you may have more nitrogen oxides which in turn will increase the load on your catalytic converter.
So the decision maybe a simple economic one, in this case.
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### Author:  [@andy\_fl](https://boards.straightdope.com/u/andy_fl)
#### Post date: [November 23, 2002, 11:51pm UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/8 "2002-11-23T23:51:43Z")
Change 336 to 56 lbs :d. Damn all this math.
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### Author:  [@Joe\_Mahma](https://boards.straightdope.com/u/Joe_Mahma)
#### Post date: [November 23, 2002, 11:52pm UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/9 "2002-11-23T23:52:48Z")
**Ringo** -I believe nitrous oxide is added to the air intake of an engine, not the fuel line.
One of the problems you would run into adding pure oxygen to the air intake is that the heat released by combustion would be a lot higher, resulting in holes being melted in pistons, and burned valves.
Maybe some of the motorheads on the board will verify these items.
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### Author:  [@Ringo](https://boards.straightdope.com/u/Ringo)
#### Post date: [November 24, 2002, 12:16am UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/10 "2002-11-24T00:16:03Z")
Yeah, the link I gave above had the “into the fuel lines” bit wrong. A much better [Nitrous Oxide Injection F.A.Q.](http://www.dynopower.freeserve.co.uk/nitrous_oxide/faq.htm) has this:
> [@](#):
>
> **How Does Nitrous Oxide Work?**
>
> There are three points. First, nitrous oxide is comprised of 2 parts nitrogen and one part oxygen (36% oxygen by weight). When the nitrous oxide is heated to approximately 572F (on compression stroke), it breaks down and release extra oxygen, However, it is not this oxygen alone which creates additional power, but the ability of this oxygen to burn more fuel. By burning more fuel, higher cylinder pressures are created and this is where most of the additional power is realized. Secondly, as pressurized nitrous oxide is injected into the intake manifold, it changes from a liquid to a gas (boils). This boiling affect reduces the temperature of the nitrous to a minus .127 Degrees F. This “cooling affect” in turn significantly reduces intake charge temperatures by approximately 60-75 Degrees F. This also helps create additional power. A general rule of thumb: For every 10 Degrees F. reduction in intake charge temperature, a 1% increase in power will be realized. Example: A 350 HP engine with an intake temperature drop of 70 Degrees F, would gain approximately 25 HP on the cooling affect alone. The third point, the nitrogen that was also released during the compression stroke performs an important role. Nitrogen acts to “buff or dampen” the increased cylinder pressures leading to a controlled combustion process.
Heh, I got part of it right.
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### Author:  [@Doc\_Nickel](https://boards.straightdope.com/u/Doc_Nickel)
#### Post date: [November 24, 2002, 2:29am UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/11 "2002-11-24T02:29:50Z")
Okay, couple of points here:
First, onboard supplies of (whatever) eventually run out. Nitrous oxide is saved for “special occasions”, as even a mild system will drain a 20 pound tank in only a few minutes. More powerful systems might get as many as two 9-second runs from a single tank.
Second, oxygen is very reactive, almost uncontrollably so. Worse, a high-oxygen atmosphere can cause petroleum products to, shall we say, rapidly self-conflagrate. In other words, mix oil or gasoline vapors with high-concentration oxygen and it could “auto ignite” explosively without any external sources of ignition.
This by itself precludes it’s use in an automobile, as there’s every chance- almost a certainty- that the fuel will explode the moment it’s sprayed out of the injector, let alone waiting until it enters the combustion chamber.
Third, the higher the oxygen content in the air taken in, the higher the fuel content needs to be to utilize it. You’ve heard of a car or engine running “rich” or “lean”? Rich means there’s too much fuel for the amount of air, lean means too little. The optimum sweet spot is pretty narrow- too lean and the engine runs excessively hot, to rich and it fouls plugs, mileage drops and drivability suffers.
Adding additonal oxygen in any noncritical or nonracing situation is a waste of materials. Once the oxygen runs out- and it’d do so far before the gas tank runs low- the system would have to default back to atmospheric. Nothing, therefore, is gained, except cost and complexity.
Fourth, yes, nitrous is added _in addition to_ extra fuel, both of which are _in addition to_ the engine’s regular fuel-air mix. Nitrous is not, itself, a fuel, it simply provides the oxygen necessary to burn the additional fuel actually injected alongside.
Nitrous is stored in the tank as a liquid, like carbon dioxide. It’s storage density is greater than oxygen, and the working pressure is lower (800 psi vs. 3,000 psi or so) so a tankful is easier to use and lasts longer, pound for pound.
And properly installed, nitrous can be saved for those “special” moments, leaving the engine easy to care for, lightly stressed and docile for regular day-to-day driving.
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### Author:  [@andy\_fl](https://boards.straightdope.com/u/andy_fl)
#### Post date: [November 24, 2002, 3:12am UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/12 "2002-11-24T03:12:05Z")
Donno about race cars, maybe they have big catalytic coverters to account for the excess nitrous oxides (maybe they dont have any). But you will surely violate environmental laws if you use nitrous without a bigger catalytic converter in a passenger car.
Also, whether you add nitrous or not, Nitrogen oxides are produced during combustion, and the catalytic converter is used to remove them.
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### Author:  [@Blown\_Injected](https://boards.straightdope.com/u/Blown_Injected)
#### Post date: [November 24, 2002, 11:32am UTC](https://boards.straightdope.com/t/oxygen-tanks-on-cars/138370/13 "2002-11-24T11:32:36Z")
Hey Joe: Yep
And also what Doc said
The idea is to make more power so the extra oxygen allows extra fuel which make more power and of course uses more fuel.
Also N2O has a bad rap for hurting engines. It ain’t bad as long as extra fuel is added.