Nitro Kits

[YT2095]

I`m sure most car owners have heard of these or have seen them in TV shows or in movies.

often as a tank under the seat and switch on the dashboard that gives instant extra acceleration.

 

now from what I understand the Nitrous Oxide simply provides extra Oxygen to the fuel mix.

 

so why isn`t Oxygen itself used!?

 

it would last loads longer as all you need to do is Up the 21% oxygen already in the air, so a slow input of pure O2 into the carb taking the percentage up a few points to say 25% should do the same thing surely?

[gonelli]

I have heard the reason NOS is better than just adding more oxygen is that using nitrous oxide provides more heat and therefore will drive the engine more than just oxygen gas. Apparently it's because when N2O breaks down to release oxygen, nitrogen is also formed. And due to nitrogen having very stable triple bonds the reaction is exothermic, which is where you get your extra heat from.

[John Cuthber]

Part of the reason NO2 works (or so I read) is that it cools the gas mixture going into the engine (because it's cold having just evaporated from the liquid in the cylinder). The cold gas going in is denser so it holds a greater mass of fuel and oxidiser in each volume. With the engine sweeping out a given volume (the displacement) you get more fuel and oxidiser per stroke with cold gas. That's where a lot of the power gain comes from. The energy of decomposition of the NO2 helps and so does the greater effective oxygen concentration.

[Rocket Man]

nitrous oxide is used in some hybrid rockets as the oxidiser, i'm not sure whether that's because it's easier to obtain than oxygen or simply easier to liquify, but it might be more reactive than O2.

[gonelli]

Part of the reason NO2 works (or so I read) is that it cools the gas mixture going into the engine (because it's cold having just evaporated from the liquid in the cylinder). The cold gas going in is denser so it holds a greater mass of fuel and oxidiser in each volume.

 

I don't really think that would be a main reason why NO2 is used, because the boiling temperature of NO2 is higher than that of O2. So if the idea was to get the mixture denser to get more into the engine, then using O2 would be the better choice.

[Rocket Man]

actually, it makes sense as a secondary effect.

if you make the gas more dense, you don't need to compress it into the inlet. if you have a regulated fuel injector, it'll keep the fuel/oxidiser in the right proportions giving it a bit of an effect like a turbo as well as burning hotter.

[YT2095]

IIRC, isn`t that what Inter-coolers are there for also.

cools the air down so you get more molecules of it per given area.

[grifter]

intercoolers are specificaly designed for use with turbos and supers as oppose to just cooling down air in the cylinders, the turbo (or Super) is cooled to increase efficiency (as more o2 mollecules can be present @ any one time due to the gas mollecules having less less Ke)

 

in response to the Why nitro question:

The addition of nitromethane in fuel provides more power therfore a smoother idle, thus making the engine easier to tune. O2 isnt used as it will combust at lower temperatures. any pure N present will react with oxygen @ the spark plugs (during a spark) to form Nox (where x varies) just increasing the ammount of combustion taking place...

 

just a quick one: perhaps another reason O2 isnt used as it will auto-combust as the piston returns to the top, therfore causing knocking, which would drastically reduce engine preformance...(not 100% sure at the pressure pure O2 combust at, might wanna chech that..)

[richard]

I think free oxygen is just too reactive. The engine would gradualy get lighter

[John Cuthber]

"I don't really think that would be a main reason why NO2 is used, because the boiling temperature of NO2 is higher than that of O2. So if the idea was to get the mixture denser to get more into the engine, then using O2 would be the better choice."

No, it wouldn't.

You can liquefy N2O (the stuff we are actually talking about, rather than NO2) at room temperature by compressing it into a cylinder. You can't do that with oxygen. To liquefy oxygen you also have to cool it. If you used liquid oxygen then the temperature would be so low that the fuel wouldn't vapourise. At best it wouldn't work. At worst you would briefly have an explosive mush then no car...

[YT2095]

actually, my O2 tank (99.5% pure, Medical grade). blows at room temp after 1 metre of silicon tube and with the gas regulator set at 4 or below, it gets cooler at about 5 and very cold at 10 (local frosting outside and close to the reg).

 

I was only thinking about a few % above the normal 21% that we (and cars) breathe.

would it have Any impact on performance?

[John Cuthber]

Expanding gases generally get cold but he was talking about boiling points. The heat of vaporisation is a lot bigger than the cooling effect of expansion for most cases.

Running oxygen into the air intake would be interesting. With a 1 litre displacement engine running at 1000 rpm you would need something like 5l/m of oxygen to raise the concentration by 1%. How much oxygen does a typical cylinder hold?

[YT2095]

my tank holds 429 litres Nominal.

 

10cm dia x35cms height, and the regulator 0 to 10 is calibrated in Litres per Minute.

[chilehed]

During WWII a lot of testing was done with a variety of oxygen-carrying agents. O2 caused lots of problems with detonation, which in retrospect isn't surprising.

 

Nitrous oxide is a great compromise between storage density, container mass, cost, and ease of transport.

 

BTW, "nitro" is nitromethane, not nitrous oxide.

 

Which reminds me of a drag car running in the blown alcohol class in Florida during the early '80's. The guy took advantage of a rule that let you run naturally aspirated using nitro and nitrous. Man, that thing hauled a**.