[praful]

Originally Posted by GTO

Engines perform better in colder weather. Primary reason : The density of cool air is a lot more than hot air. Thus, you end up with a superior burn, which results in better performance & efficiency.

Pardon me for the noob physics doubt!

But denser air also means more drag right?

So shouldn't there be any difference on performance and efficiency as the body of the car has to work harder to overcome wind resistance?

[jigbarai]

Not any noticable change in throttle response, but yes - definately better FE figures in winters since AC use is minimized.

[JayD]

Originally Posted by GTO

Engines perform better in colder weather. Primary reason : The density of cool air is a lot more than hot air. Thus, you end up with a superior burn, which results in better performance & efficiency.

Over the winter season, I've noticed a distinctly sharper throttle (compared to the harsh summers), the engine seems smoother and revv-happier. This effect is even more pronounced with diesels (especially the Jeep). It is around this premise that the cold-air-intake industry exists, and whatever the season, your engine will feel sharper at night than at noon.

Are you feeling it?

Yep! My intake air temps are down to the 25 range, from 40 plus usually. Even in the evenings i'm pulling in 31-33 from the normal 50+. Response seems a lil better, and FE is showing a massive increase!(Another factor is that i don't use the A/C much now) Overall, I'm loving it.

[ask77]

yes ! especially here in the north where the temperature difference between summers and winters is huge there is a very perceptible difference in engine performance. The engine is much smoother , there is much less engine noise although that may be because the radiator fans are running lot less and of course the FE is much better because the a/c is not running and you can actually switch off the engine on a red light !

[asitkde]

Originally Posted by akshay4587

I am sure,most of us idle cars,till the RPM settles down to normal.

I have a question and I think it is related to the thread. When I start my car in the morning (ambient temperature is about 15 degrees, say), idling rpm is more than 1.5K, actually quite close to 2K. Within a few seconds (at most 5 seconds) of idling, the rpm comes quickly down to about 1.1K and stays there. This is when I usually start moving. The normal idling speed after a full warm-up is about 900 which is attained after a few minutes of driving (I try not to cross 2.5K during this period). Is it necessary to idle the car to the point when the fully normal idling speed is achieved? I thought cars of this generation did not need an elaborate warm-up, apart from the initial few seconds. Is my thinking wrong?

[SS-Traveller]

Originally Posted by praful

But denser air also means more drag right?

So shouldn't there be any difference on performance and efficiency as the body of the car has to work harder to overcome wind resistance?

It's not THAT dense!!!

Denser air = more oxygen in it = better fuel burn.

[dhanushs]

Originally Posted by praful

But denser air also means more drag right?

True! but for drag to show its effects on FE, you should be traveling well above triple digit speeds all the time.

Windows down or A/C on might give you some insight.

[mercedised]

Engine runs cooler, this also has a effect on the better engine feel. Just like night driving, one might consider,as if, we drive all the time as in night, in winter. (lol.. )

[.anshuman]

The Laura manual clearly states that the Engine when cold does return a very low FE until it warms up. Up here in the North where we have shivering cold winters, the Diesel engine takes forever to warm up, until then it sounds crude irrespective of the make.

But Yes after they warm up the performance is a lot better thank to the FREE cold air intake for some months. FE is also better thanks to the reduced AC usage.

[Technocrat]

Yes, I have noticed this both in my bikes & car in Pune. The engine runs smoother & the FE is more.

But yes when it gets very low, it takes some time for the engine to come to the ambient operating temperature before it can perform well.

[shuvc]

In places where temperatures drop below say 10 or 5 deg, what effect does the cooler air have on cars fitted with cold air intakes? Would it further cool down the intake air?

[Hashim]

Yes I am feeling better performance from my car too.. much better throttle response even in LPG and lesser down shift of gears. I know as I travel from same road everyday and my hands almost know instantly which gear to put at which turn, but now car stays in power band and it does not knock. Only trouble is getting it idle properly first time in morning, thanks to age of the car and weak ignition system. Although it starts with a single click of the key but doesn't idle when started cold in morning. Rest of the day its fine.

[khoj]

Originally Posted by asitkde

I have a question Is it necessary to idle the car to the point when the fully normal idling speed is achieved? I thought cars of this generation did not need an elaborate warm-up, apart from the initial few seconds. Is my thinking wrong?

Well, what you are doing is quite acceptable. If you could wait till the engine attains its normal idling speed that would be ideal but is not essential.
As for the current generation of engines they are still made up of metallic bits and different kinds at that. You want all of the different bits to have attained a working temp before you load them up and it is always best to have metal running against metal with a bit of hot lube in between them. So while a warm up is still desire-able, modern day metallurgy & chemistry have ensured that the time taken to warm up now a days is much much shorter than what the engines of yore used to take.

[GTO]

Originally Posted by phamilyman

What you have in Mumbai is hardly winter - I know friends who swim even in December!!

So true. But 20 degrees is better than the 45 of summer

Originally Posted by SS-Traveller

The fuel density is also higher, the AC is turned off (no/minimal compressor load), and the engine oil maintains its viscosity better in cold weather. Result: The engine sounds more silent, revs more easily once warmed up, and gives better FE. My Scorpio returns about 1.5 km/l more, and the Swift about 2 km/l more than in summers.

Thanks for sharing the additional points. Very insightful post.

Originally Posted by shuvc

In places where temperatures drop below say 10 or 5 deg, what effect does the cooler air have on cars fitted with cold air intakes? Would it further cool down the intake air?

I would think so. However cold the outside air, the engine bay will always be warmer / hotter.

[driving_smartly]

Is it Advisable to keep engine Idle till the temperature guage shows that engine has warmed up. I did this recently before my visit to my native place, the ride was smooth throughout. Filled the tank full, then did 363 kms (Return) with almost 60% AC. My Santro took 19.27 litres cutoff at petrol bunk. An average of 18.84 kms per litre with 4 passengers and luggage. Speed was maintained between 80-100. Though i had driven very sedately but still i had to accelerate heavily in 3 ghats for overtaking