What outside temperature is our engine's favorite?

[N8dawg]

first time it went below freezing for me and it felt like a rocket ship. What's the optimal outside temperature for our engines?

[PhillyNate]

Dude, I've been waiting for someone to bring this up. Ever since Fall has come and the lower temps my car has been an absolute... well "rocket ship." Especially in the higher rev range. The car has been downright scary from 5.5k rpm on up. And I'm as pleased as can be. The colder it gets, a new personality emerges from the engine bay. I kind of expected this with the type of intake setup we have on these cars but DAMN.

[swamp2]

Colder the better and higher density typically goes along with colder temperatures. Of course the cold starts are not good on an engine (nor batteries, belts, and a slew of other car things) at all but if the question is purely about power then colder the better. Growing up in Alaska the coldest parts of the winter (-40 to -50 deg F) made for some serious bumps in power.

[robb7979]

Tires don't like it either. Isn't -40 the "magic" temp for different type of oil? It sticks in my head for some reason. But yep, colder air is always more dense. It's usually drier in the winter too, which is also denser than humid air.

[BPMSport]

The colder the better to an extent. It becomes a balance of the variables. There is no "magic" number.

You have to look at:
1. Air Density (colder air = denser air = more oxygen available for combustion) End result is ECU runs more timing and car makes more power. The difference between very cold and very hot can be a significant amount of horsepower.
2. Traction in very cold temperatures might be an issue
3. Oil/Coolant configuration should match environment car is located in

[FormulaMMM]

Dude, I've been waiting for someone to bring this up. Ever since Fall has come and the lower temps my car has been an absolute... well "rocket ship." Especially in the higher rev range. The car has been downright scary from 5.5k rpm on up. And I'm as pleased as can be. The colder it gets, a new personality emerges from the engine bay. I kind of expected this with the type of intake setup we have on these cars but DAMN.

Temperature really does make a huge difference, and it's not unique to the M3. E39 M5 is an absolute snore in temps. >80-85, but in the cold a monster across the whole rev range.

[JJM335]

About 65 is my favorite. The car is peppier but the tires aren't too cold.

[JonnyM3]

Drove in a some 48 degree weather the other night. Did a few first to third pulls, hooked up every single time and the car felt great

[mdosu]

low 50s. And if you have heated seats and vert, better drop the top.

[NYCM3ryder]

haha funny i saw this bec this morning when i got up for work ad 7am it was nice and chilly... once the car was wamred up.. M-mode was engaged and wow!!!!!! she was ALIVEEEEEEEEE..... cant see a better way to start the morning off... got to work with a big smile on my face hahaha.

[SchnellM3]

Originally Posted by Mike Benvo

The colder the better to an extent. It becomes a balance of the variables. There is no "magic" number.

You have to look at:
1. Air Density (colder air = denser air = more oxygen available for combustion) End result is ECU runs more timing and car makes more power. The difference between very cold and very got can be a significant amount of horsepower.

This, plays into the same thing with flying you get better power, lift and bite out of the prop due to the denser air.

No doubt the M loves the cold air and the sound is just terrific. My bike with the Akra on it sounds menacing as well, but the tires that I have on it don't like the cold weather so much...

[Titanium Silver]

Originally Posted by JJM335

About 65 is my favorite. The car is peppier but the tires aren't too cold.

+1. If it is too cold the tires don't get good traction from start. Just lots of hop off the line.

[N8dawg]

Originally Posted by swamp2

Colder the better and higher density typically goes along with colder temperatures. Of course the cold starts are not good on an engine (nor batteries, belts, and a slew of other car things) at all but if the question is purely about power then colder the better. Growing up in Alaska the coldest parts of the winter (-40 to -50 deg F) made for some serious bumps in power.

Does density coincide with what normally is humidity? For example when Florida is 45 degrees will it be denser than when Nebraska is 45 degrees?

[tlr]

Originally Posted by mdosu

low 50s. And if you have heated seats and vert, better drop the top.

I love driving in cool weather with the top down, seat heaters on, heat blasting.

[Ateam]

2 things to keep in mind-

1.In regards to humidy, keep in mind that colder air holds much less watever vapor than warmer air. Therefore "80 percent' humidity in 100 degrees is WAY different than 80 percent in 40 degrees. The effect of humidity is almost nothing once you are below 40 degrees as the air cannot hold a lot of moisture so.

Point is that colder temps are a "double benefit" in that you get the colder denser O2 and you get much less water vapor mixed in for any given humidity.

The small tradeoff is some states change their gas formulation for "winter formula" contains more butane in order to modify the relative vapor pressure of the of the fuel between winter and summer. Butane, similar to enthanol makes our fuel have less energy content and basically winter fuel is a bit less potent than summer fuel. Still a net beneft in winter thought

2.The most accepted rule of thumb is that 10 degrees F change= 1 percent hp change.

So about 4hp for every 10 degrees for our cars. so from summer 100 degrees to 30 degrees is almost a 30hp relative increase. this does not take into account the lower humidy effect in winter so with that its probably more along the lines of a 30-45 hp difference between winter and summer. That shows you how much a true 30 hp difference is, VERY noticable.

[Daft]

And adding boost in combination with the cold temps only amplifies the power gain. I wonder how my car will feel in well below freezing temps this winter. Insane power I'm sure but useless on snow/icy roads..

[apecush]

-22C is not its favorite temperature for idling, that is for sure.

[RizOne]

Low to mid 50's is best for most engines. Performance tires like some heat in them for grip so they need a higher temp. So good compromise is about 60 degrees, and with some heat in the tires you can get some stick.

[Ateam]

He is not asking about what temps our tires like or what temp gives you best time around a track, rather he asked what the ENGINE did best in and the answer to that is as cold as possible without being so cold that it is detrimental to the parts. 0 F is great for power once fully warmed up

[RizOne]

Why not minus 100 degrees then? I assumed he wanted to drive the car.

[Ateam]

As I mentioned the internals and parts have to work. engine would not work at -100

as cold as the engine can still actually run and warm to temp is the best temp for max power