cold air

I see the smiley, but in case you're curious, it does 160 mph, but not
at Mid Ohio. You see you have to brake for a ~70 mph turn long before
the car has a chance to reach its top speed. A Camry would probably
do well to hit 105 mph there.

Jim C.

 

1. Why would you want MORE hp in freezing weather when driving conditions
suck?
2. Don't the fueling stations in Canada change to a different formulation of
fuel in winter? ( I've heard it explained as the winter mix and summer mix)
This could potentially be a part of the loss of MPG?
3. This has got to be one of those questions that is injected into a forum
to drum up a bunch of debate and flame. Do you really care if you have more
HP in -30 degree weather if you only drive to work and to the grocery store
in that climate? I'm a big fan of trying to cope with driving conditions and
making it safely to my destination.

If this was some sort of racing type of situation, I'd still feel the same.
NOONE races in these conditions except the World Rally Cup guys.. and they
are only concerned with staying on the road!

Stepping off my soapbox..
Ric

 

After reading all the replies, I guess the general consensus is that the
advantages of cold air (denser, better combustion) are overshadowed by the
disadvantages (denser air = more drag, more work for engine to stay warm) at
a temperature of around 50 degrees.

This is of course, modifications aside (intercooler, ram air, boost)

Seems reasonable, except for what fbloogyudsr said about fuel not atomizing
well in cold air...didn't quite understand how that works.

As for ram-air, aren't effects only noticeable at higher speeds? (some sort
of linear relationship between small power gain and speed of car)

-sachin

 

1. Why would you want MORE hp in freezing weather when driving conditions

Posted as a theoretical question. The only factor I mentioned was
temperature...not humidity or precipitation.

Wasn't talking about MPG either. Purely theoretical intake temp vs. HP
question

forgive me if I imitate your style in replying:
1. This was a theoretical question. I asked for numbers to see whether or
not, under other CONSTANT CONDITIONS, HP would change as a function of
intake temperature

2. Not everyone has the same standards of cold air as you do. I only cited
numbers as examples. Being ignorant to the answer of the original post, all
I wanted to know was if cold air is better. Doesn't matter where go you, be
it work or the grocery store.


don't label trolls before you properly read and understand the OP, and
realize the curiosity of the original poster.

-sachin

 

Intercoolers are fitted to reduce the intake temperature to a reasonable
level such that the engine will not overheat and explode, which is not quite
the same as reducing the temperature to get more power.. your second
statement speaks for itself..

 

It is good to know that my Jeep GC has more power when sitting on the
driveway having been started in cold Canadian weather.. I am not so happy
that driving away with fulltime 4x4 engaged, heater in full swing and all
lights ablazing is sapping this new found power.. but I have a question.. is
it true that Chinese Bingo halls in Toronto (or anyplace) number the bingo
cards from right to left?.. just a theoretical thing, ya know.. lol

 

Apparently they change (or used to) the formulation 4 times a year here in
Manitoba. I mean the gasoline formulation. Not sure how many times diesel is
changed - twice anyways.

It is actually the depot or refinery that does the change, not the "dispensing"
station where we fuel up.

It could be that this is a loss in MPG, but how much is the question. Anyone
ready for a M.Sc. thesis topic in Chemical Engineering? The volatility of the
gasoline HAS to be increased for winter combustion so the products will have
lower BTUs and thus lower MPG. . Last week at -41C I flooded my Voyager when
trying to start it, and used ether to start it up. At -41C the top of the carb
had a small pool of ether just sitting there. It "quickly" evaporated, but you
could see it do so, just like at that temp you can see liquid propane sizzle
away.

 

I know, I'm just messin' with ya. -Dave

 

The question was "Does cold air make more power", or something along
those lines. The answer is an unqualified "yes".

The fact that people drive more slowly due to slippery conditions
doesn't change that.

 

Intercoolers mean lower temperatures, which means the air is more
dense, which means you can add more fuel, which makes more power.

http://www.ford.com/en/innovation/engineFuelTechnology/hydrogenInternalCombustion.htm

It's not exactly what I was thinking of, but it's similar.

 

This is because your intercooler is much more efficient. Heat transfer,
with all other things being equal (materials, distances etc) increases
with increased temperature difference. So, assuming an air/air
intercooler, when the coolant (outside air passing through the
intercooler) is colder, it can take more heat more rapidly from the
pressurized air. The same holds true for a water/air intercooler, but
there is the added step of air/water (at the rad), water/air involved
(at the intercooler).

I don't know this for sure, but my take on intercoolers is that the
primary benefit is not to lower the temperature of the air entering, but
to increase the density (PV=nRT). So, given the same n and R (specific
to the gas in question), lowering the Temperature lowers the PV
(Pressure time Volume), thereby increasing the amount of oxygen
available in one opening of the intake valve.

Again, the losses occurring between the engine and the cold outside air,
negate most of the gains of charging the intake with cold air.

Dan

 

Some companies make "winter gas", mostly to stop gas-line freezing. It
probably does reduce efficiency.

Lots of us want more power in the winter. Hauling snowmobiles, plowing
snow, cutting through snowbanks. Driving conditions don't suck, drivers do.

Lots of people race in minus 30!! Snowmobile/ATV races, ice racing
(both cars and bikes). It is a whole cultural thing. Love it or die!

|>))

Came out of a meeting the other night with a transplanted American
couple during a snow storm. The wife said, "You Canadians, you love
this. You like the challenge" (I think they are from Florida or the
Carolinas). But I thought, we don't even see it as a challenge, it is
just life, it is what we do.


Dan

 

Today I drove 280 km from rural Manitoba into the city. Average mpg was 24.6 while in
summer I get 27 or 28. Today was warm about -4C and there were lots of snowmobilers out
cruzin. several at the gas station I stopped at for coffee commented that their snow
machines were overheating. When I mentioned the -41C temps of about 10 days ago no body
wanted those days back.

 

And your *tires* at the same ambient temperatures will, in an inverse
ratio, produce a much higher 'Pucker Factor' as you enter the Esses.
=8^O

 

Ahh, another one o' them Porsche weenies! Try Road America when it
snows! You might want to swap out of the 968 for a Quattro ...

Seriously, the problem we start running into is tire compounds. As it
gets colder, they get harder, so it's tough to stay *on* the track
just as you're starting to make *real good* power out of that cold
air. This brings on our standard Badger Bimmers' OktoberFAST morning
lecture:

Cold air makes two things: *more* power and *less* traction.

 

Seriously, the problem we start running into is tire compounds. As it

Interesting...however can't one assume that friction (above a certain speed)
keeps the tires at a steady temperature that is not cold enough to be too
detrimental to the tire grip?

 

Unfortunately, Dan, most of our anecdotal experiences are "unscientific". You
have experience in lighting and I do tip my hat towards that expertise. No
B.S., you DO have experience based on data - cold hard facts.

Unfortunately, most of us, IMHO, are not as well endowed nor as well connected
as to obtain cold (no pun intended) hard facts. We can only compare in an
anecdotal way what happens when we drive in "warm" temps and then when we
drive in a normal on Mars day when the temps hover about -40C. Most readers,
IMHO, do not use the "scientific method" to test any null hypothesis, or any
other hypothesis. The average reader simply does not have the necessary tools
to conduct the study and the necessary analysis in an unbiased manner.
Furthermore, the average reader cannot control ALL variables. When we "make
assumptions" we by necessity introduce biases - but we all know that don't we.

Yes, the textbook stuff is based on hard cold facts. Unfortunately, our cars,
don't always behave as the textbook suggests they "should" behave. Assumptions
mask a LOT of reality.

Lets move on to another issue. Besides, it is getting warmer since the
"average' temp has bottomed out in the Northern hemisphere - it is now
February after all. Racing weather is only about 4 months away in Canada and
this talk of cold air will then be another interesting but of no consequence
discussion, because in 4 months the question at hand will be can I "win" the
next race, not what is the thermodynamic efficiency of my vehicle at 70F

Today it was about 0C (32F) and my Voyager accelerated "much better" IMHO than
it did nearly 2 weeks ago when it was -41C (-43F).

Ken

P.S. I have removed the other two news groups because I do not believe in
cross-posting to news groups that I do not subscribe to.

 

You're absolutely right. As it gets colder its definitely a tradeoff
between extra power and less grip. You have to be *extremely* careful
about warming up tires in cold weather conditions and realize that
they probably won't reach optimal temperature like they will when its
in the 70's.

Most of the time I run Hoosiers, and they still manage to heat up
pretty well when the temperatures are in the mid 50's, though they
take considerably longer than usual to do so. In fact my personal best
lap time at Mid Ohio came on a 55 degree afternoon. Other tires like
the Michelin Pilot Sport cup simply refuse to heat up when the
temperature drops below 60 degrees, and are almost undrivable in those
conditions.

Jim C.

 

Friction will definitely heat a tire up, but depending on the track
temperature, and the tire compound, not necessarily enough to attain
optimal grip.

Jim C.

 

And that's fine, but to do as you did, to answer a question wholly
different to the question that was asked...why? What's the point?

DS