Engine Oxygen Consumption

[Krian]

Hey, just been reading up a bit on NOS and trying to figure out how everything works, and i've got a question or two that i'm hoping someone can answer:

Nitrous works by increasing the amount of oxygen within the cylinder during combustion, right?

The colder the air the more oxygen rich the fuel/air mix is, hence the need for a choke - to provide more fuel when the engines cold so the oxygen has something to burn with, right?

If thats the case, can you do something to cool the air getting into the engine, then run the engine with a richer fuel/air mix to increase the power of the engine?

Is that all correct or have i got it wrong again?

 

[Dusk]

Just go and buy a nos kit.

 

[Krian]

I was asking to make sure that my theory of how a nos kit worked was correct and whether you can attain a consistant power boost via air cooling rather than a temporary boost via the use of nos.

I'd kinda prefer to go without a nos kit tbh.

 

[Dusk]

Yep, but i dunno what you could use...

 

[Demarest]

The only other way to increase the cold air intake is relocating the air intake pipe to the front of the grill (away from the heat of the engine bay) , or outside of the car somewhere, e.g. an air intake on the bonnet. Intercoolers do the same job as well, but i think that these are only used with turbochargers. I have also heard of CO2 kits that apperantly cool the intercoolers to get even cooler air. But dont take my word for it tho.

 

[Andrew]

That isn't what a choke does - it isn't for when the air is cold, it is for when the engine is cold. Petrol has a problem fully vapourising when the engine is cold, so you need to put more fuel in for the engine to run. Cold start enrichment is a better term.

Also, you don't want the engine to run richer. You want to get both more fuel and air in, but maintain the ratio.

Cooling the air isn't really viable, apart from a cold air intake. Intercoolers are only used on turboed cars as the compression brings the temperature of the air well above ambient. If you tried it on a NA car, you would just be trying to cool the intake air with the intake air, which clearly won't work.

 

[Krian]

I was thinking something along the lines of fitting an air scoop to the front of the car (hidden by a nice grill so it wouldnt look too tacky!) and then trying out a few things from my overclocking days to cool the air.

Hopefully if i could figure out the ratio and increase the fuel mix then id get more power.

 

[Ed]

Not the same. Nitrous contains more oxygen per mass than the air does. Hence why it makes more power. To make a noticable difference from air you would have to really cool it. This means removing heat energy from the air at a very fast rate = very impratical.

Ed

 

[Krian]

Ed: Yeah, I kinda came to the same conclusion, but what about increasing the air pressure? Say from standard atmosphere (umm, 30psi I think) up to 60psi? That would give you more oxygen molecules per square inch, and if you increased the fuel flow to go with it wouldnt that give the car a bit more oomph?

 

[Turtle]

I think its about half that figure Krian, time to consult wiki again for me :unclesam:

 

[detox]

know this is not what your on about but this is useful

NOS = 40% oxegen
AIR = 20% oxegen

 

[Andrew]

Ed: Yeah, I kinda came to the same conclusion, but what about increasing the air pressure? Say from standard atmosphere (umm, 30psi I think) up to 60psi? That would give you more oxygen molecules per square inch, and if you increased the fuel flow to go with it wouldnt that give the car a bit more oomph?

That's called forced induction, i.e. a turbo or supercharger.

Atmosphere is about 14.7psi.

 

[Andrew]

know this is not what your on about but this is useful

NOS = 40% oxegen
AIR = 20% oxegen

I don't know where you got those figures from, but they aren't right.

Air contains 21% oxygen. Nitrous oxide contains 33% oxygen by volume once decomposed into nitrogen and oxygen.

But when it goes into the cylinder it is nitrous oxide, and the heat of combustion causes it to become nitrogen and oxygen. For every litre of nitrous oxide gas entering, you will get about half a litre of oxygen. So from that respect you will have 50% oxygen.

Either way, neither is correct; it's quite a complex mechanism and at the end of the day, it is useless comparing oxygen content and easier just comparing power gains.

 

[Krian]

That's called forced induction, i.e. a turbo or supercharger.

Atmosphere is about 14.7psi.

Ah, k, so thats what superchargers do I was just trying to figure out what would happen if i stuck an air compressor on meh air intake - I think K10's use a venturi type carburettor, so I thought the fuel air mix would take care of itself.

Hence all the questions