Jump to content

Horsepower and cold weather


juniper

Recommended Posts

I was wondering if someone knew how much HP increases in cold dry weather. I was driving my wife's V8 audi mid sized sedan, that usually isn't very peppy, and I can always feel additional weight when driving it, like extra passengers, or the spare tire in the trunk. I drove it the other day and it was cold and dry and it feels like there is around 35 additional HPs. So if a car has around 350hps approximately how much would it increase if it was around 5 below zero and 10% humidity.

Link to comment
Share on other sites

Every motor will respond slightly differently to a cool charge... but they all will improve.

I dont think you are going to get 10% better output... +35/350. That is unless that baseline was done in bad conditions.

Also, temperature is only one component... density is very critical, probably more than temperature.

Link to comment
Share on other sites

There is no question cars have more initial HP when cold.  Heat kills HP.

 

As with any modern water cooled engine I would expect when the optimum operating temperature is achieved then HP and engine performance should be consistent.

  • Like 1
Link to comment
Share on other sites




There is no question cars have more initial HP when cold.  Heat kills HP.







 







As with any modern water cooled engine I would expect when the optimum operating temperature is achieved then HP and engine performance should be consistent.



Absolutely. As the air is colder, my understanding is that the oxygen is denser, allowing more combustion to occur. Similarly, that's why Fireworks burn brighter (but shorter) in the winter.

Sent from my SM-G920V using Tapatalk

Link to comment
Share on other sites

That's why the Corvette has reverse coolant flow to allow higher compression and the computer backs the timing down if pinging gets close. Then again your vehicle might be 2 quarts low on oil giving you about a 20% gain in horsepower. That's another reason why the Vette went to a dry sump system to keep the crank out of the oil bath.

JJK

Link to comment
Share on other sites

  • Moderators

It's not just the denser air, it's also colder fuel, remember "cool cans". The cool can went under the hood and the fuel line went through it in a coil giving as much time in there as possible. You would fill the can with ice cooling the fuel before a run, I don't know if it was just a fad that passed with no noticeable improvement or it did help but i do remember them.

CoolCanBlack.jpg

  • Like 1
Link to comment
Share on other sites

5 hours ago, YK Thom said:

Jeep does better in winter up here.

Crikey.  Just noticed...North West Territories.  God knows how anything does anything at all up there!.  My people believe that anytime it's too cold to be naked, it's too cold.

 

Dave

  • Like 1
Link to comment
Share on other sites

11 hours ago, juniper said:

I was wondering if someone knew how much HP increases in cold dry weather. I was driving my wife's V8 audi mid sized sedan, that usually isn't very peppy, and I can always feel additional weight when driving it, like extra passengers, or the spare tire in the trunk. I drove it the other day and it was cold and dry and it feels like there is around 35 additional HPs. So if a car has around 350hps approximately how much would it increase if it was around 5 below zero and 10% humidity.

 

The only way to know for sure is to put the vehicle on a dyno and make a few runs. You'll end up with an uncorrected figure for HP and torque, that is good for that day and those conditions.

 

Those numbers would then be corrected to the SAE J1349 Standard, using 77°F, 29.235 in/Hg (or 990 mb) and 0% relative humidity.

 

There are dyno/horsepower correction calculators all over the internet. But they won't tell you anything unless you know the atmospheric conditions.

 

http://wahiduddin.net/calc/calc_cf.htm

 

http://www.superchevy.com/how-to/ghtp-1109-fact-and-fiction-of-dyno-correction-real-wheel-horsepower/

 

http://www.dynojet.com/products/dynamometers/Automotive-dynamometers.aspx

Link to comment
Share on other sites

30 minutes ago, Mallette said:

Crikey.  Just noticed...North West Territories.  God knows how anything does anything at all up there!.  My people believe that anytime it's too cold to be naked, it's too cold.

 

Dave

You have some wise people. Not sure what happened to us.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...