Science behind 'Colder air = More Power'

[Mike1234]

Right, whats the science behind 'Colder air going into the engine = more power'?

Does colder air react with the fuel to combust better or what?

[Pommy]

even I know colder air = more oxygen = bigger boom = power! google could have told you that dude..

[grandell]

cold air is more dense, hence more air 'per litre', therefore more oxygen as well, which means you can burn more fuel


and yeah, google or search would've told you that

[Mike1234]

Yea, thought about googling, but hearing it off someone who knows is alot better. Cheers Mang

[Lycanthrope]

Air expands when warm, so the colder it is, the more air you can fit into the cylinder (the air will be more dense and richer in oxygen). The ECU will then add more fuel to match, resulting in an overall more powerful combustion.

[Mike1234]

Damn noob ehs, clogging up the forums

Will search next time

[BUMP]

Its all relative

[Coupe-R]

Air expands when warm, so the colder it is, the more air you can fit into the cylinder (the air will be more dense and richer in oxygen). The ECU will then add more fuel to match, resulting in an overall more powerful combustion.

[grandell]

Originally Posted by Mike1234

Damn noob ehs, clogging up the forums

Will search next time

haha no worries man
next time someone wants to know they can search and they'll have this definitive guide come up, so its all good

[DrRubber]

google volumetric effeciancy (sp) thats all you need to know

[TakeiTeg]

no dumbass, hot warm air = more power coz hot air is hot and more hot = power, just like hot girls have powar and like when you a cold you usually can't run till you're warmed up so mount your air filter beside the extractors for maximum powaerrr..

[Robbie]

Originally Posted by TakeiTeg

no dumbass, hot warm air = more power coz hot air is hot and more hot = power, just like hot girls have powar and like when you a cold you usually can't run till you're warmed up so mount your air filter beside the extractors for maximum powaerrr..

haha, that sounds convincing yeah rofl

[Coupe-R]

now you can see you prob use more gas in winter than summer. Possibly

[Vlad]

Originally Posted by Coupe-R

now you can see you prob use more gas in winter than summer. Possibly

cause it gets cold and i run the a/c?

[doo0T!doo0T!]

Properly atomised fuel helps make power too as more molecules are available to oxygen to react with
Just like a lump of coal, a lump of sulpher and a pile of salt pitta is fine but if you crush it up into a fine powder you've suddenly got gunpowder!

(hot fuel, small particles) + (cold air, higher oxygen content per volume) =

[chromies ea]

I wonder if anyone has run pure oxygen in a nitrous type setup for drag racing, considering air only contains 1/3+- oxygen it could give decent gains.. and n/a engines wouldnt be bumped into forced induction

[tarmac-]

LOL at your avatar doot...

Yeh, hot air expands and rises, so less oxygen in a given "cube". I wonder how much the ecu actually would compensate, if at all, with cold vs hot air.. O2 sensors are for pussies anyway :p, just tune it correctly without and be done with it

[Ped Rac3r]

.

[Colza]

Originally Posted by tarmac-

I wonder how much the ecu actually would compensate, if at all, with cold vs hot air...

Lots.

In a MAP sensor system like Honda uses, the mass of air is calculated from the other 2 variables: temperature and pressure. You need to know two of them to work out the third, temperature is definately taken into account.

[doo0T!doo0T!]

Originally Posted by chromies ea

I wonder if anyone has run pure oxygen in a nitrous type setup for drag racing, considering air only contains 1/3+- oxygen it could give decent gains.. and n/a engines wouldnt be bumped into forced induction

There is no point, the Nitros is the oxidiser not the fuel, you add nitros you have to add fuel for it to react with.
So Nitros + oxygen just gives a whole lot of oxygen

Normal air + Nitros oxide = more density of oxygen than breathing pure oxygen.
Also storage of pure oxygen is super super super dangerous, in the presence of only 60% oxygen the fat in your own body becomes as combustable as petrol is now!
Steel burns, aluminium burns violently. basically everything except inert substances will burn and things will get very hot very fast.

It's more dangerous to carry oxygen than fuel because if an oxygen bottle ruptures everything around it becomes fuel!!

Btw our atmosphere is only about 21% oxygen on average, Has been measured as low as 11% in some cities!

[grandell]

Nitrous oxide + nitromethane ftw! they're running that on some of the drag cars in the states...


hmmm, got off topic? sorry

[jdmdc2]

yea bro get a pod filter up near your bumper and u will easily take 2.5 seconds off your 1/4 mile times..

[EG_GTI]

Ahhh.. too much science - it makes my head hurt.

[grandell]

man you guys know nothing... don't you know hot air's better?

As temperature increases so does the potential energy contained within the oxygen molecules in the air. This potential energy increases the rate of combustion allowing more fuel to be burned faster.
Also the more energetic the air is the faster it will move. Therefore as the valves are only open for a certain length of time, more hot air will be able move through into the cylinder than if the air was cold and dense. Think of the difference between coke and a thickshake, you can't suck a dense substance like a thickshake as quickly as you can suck something more fluid like coke.
This faster flowing effect also has an effect inside the combustion chamber, where the faster flowing air increases the swirl effect allowing a more even distribution of fuel and air.

[Borat]Naaat![/Borat]

[Hayce]

^^ hmm better bin my IC for an extra heater then huh... Common sense kitty just got killed.