[TiAg335i]

So in NY we've been having pretty brisk temperatures...this whole week has been around mid 30's..

But wow, when I merged onto this two lane highway and stepped on it...it just felt like a BEAST! The power delivery was so linear, and I felt my back being pushed into the seat for real this time. Haha, i was grinning the whole way home after that. Amazing what cold temperatures can do...

Any reason for this? It was so noticeable that I almost felt I had a procede or something installed in my car.

[BzsBimmer]

colder air

[darkphantom]

NA engines like warm air

F/I'd engines like cold air

the reasons behind it? too lazy to look it up.

[mroach]

From the Wikipedia article on intercoolers: A decrease in air intake temperature provides a denser intake charge to the engine and allows more air and fuel to be combusted per engine cycle, increasing the output of the engine.

[tpipta]

Cold air is more dense, equals more CFM's which equals more power.

Originally Posted by darkphantom

NA engines like warm air

F/I'd engines like cold air

the reasons behind it? too lazy to look it up.

[noro]

Originally Posted by darkphantom

NA engines like warm air

F/I'd engines like cold air

the reasons behind it? too lazy to look it up.

NA engines like cold air too.

[TiAg335i]

I think this is the reason why the Bugatti has like 4 radiators or something...

more power = more heat
less heat = more power

[Cloud9blue]

more to do with the thermo efficiency of burning cold air than the density.

thats the reason Porsche used expansion intake manifold for the new GT2, even though it causes some decreases in air density.

[sailvi767]

Originally Posted by darkphantom

NA engines like warm air

F/I'd engines like cold air

the reasons behind it? too lazy to look it up.

All engines like cold air forced induction or NA. Cold air is more dense allowing the engine to run more fuel for a given fuel air ratio. More fuel equals more power at static ratios.

[darkphantom]

Ah sorry, I was thinking of altitudes for NA engines. Higher altitudes better for F/I lower altitudes better for NA.

Thanks.

[anerbe]

Originally Posted by AlpineCloud9

more to do with the thermo efficiency of burning cold air than the density.

thats the reason Porsche used expansion intake manifold for the new GT2, even though it causes some decreases in air density.

i believe you're somewhat right

density constant of air has to do with the temperature. cooler the temperature, the denser the air. denser the air, the more mass (energy) it has per unit volume. you're probably talking about pressure decrease. thats why Charge air coolers are on their turbo cars, although they cause less PSI pressure, they overall get more power by lower IAT's which outweights the PSI drop

the Porsche expansion intake manifold is utilizing engineering flow properties which requires exacting dimensions, and tons of testing. i'm assuming it has some sort of venturi effect which keeps the flow properties, but expands the air, cooling it

*content warning - scientific*
because typically when you decrease the flow path cross section, you drop pressure and increase velocity, and when the path increases, you drop velocity of the air, with overall lower pressure before the restriction.

if you engineer a restriction properly, you can get what's called a venturi effect. with this, if you design the restriction angles, radii, etc... properly, you can actually have the velocity maintain speed from the restriction to the expansion, and sometimes accelerate it further even if the cross sectional area is larger. combine this with air when it expands, it cools, and you can get a great boost. I did something similar to my school's formula SAE race car, where I developed the intake system.

[bsamoul]

That's why I love winter time!

[Deda]

that is so cool!

[Strongmad]

Originally Posted by AlpineCloud9

more to do with the thermo efficiency of burning cold air than the density.

Actually, it has everything to do with the density of the air, because of what mroach posted

A decrease in air intake temperature provides a denser intake charge to the engine and allows more air and fuel to be combusted per engine cycle, increasing the output of the engine.

[Universal_Magnetic]

You will see a performance increase, but with colder temps its also harder to get good traction

[Omni]

I've been feeling it too these past few days. It's friggin awesome. Acceleration and throtte response is way better - even in the lower end of the power curve.

[branabolic]

20 degrees all week, car screams!!!

[ragingclue]

Originally Posted by branabolic

20 degrees all week, car screams!!!

So do my RFT's. Can't get traction in the morning for sh*t

[alq80]

yup it's all density!
i love forced induction

[328skidpad]

comon someone post the real numbers, I remember a post a few years ago on e46 fanatics for a 330 e46 it was something like 1-2 horsepower for every 10 degree decrease in temp.
Enjoy the boost

[BMW F22]

I've noticed that too. It's been a bit chilly around here and I felt the car was snappier. At the same time I've also noticed a bit worse fuel economy.

[ncoig]

Wonder if I'll be disappointed in the power when my car gets back over here, then. Warmer here, and onl 93 octane vs the 95 I was feeding her over there.

-N