ChrisB

It is cold in Vancouver today.
- 1 degree Celsius ... 30 degrees F. Just below freezing.

On the way home after a long day of work, on a deserted country road - i decided to do a standing start on dry pavement.

I must have mashed the accelerator just right - because the V-8, E550 took off like a real beast. The jolt of power really brought a smile to my face.

I know NA engines like cool air - like an inter-cooler gets more HP / Torque.

I must have been well on the way to a well below sub 5 second 0-60 run. Took my foot off the gas because my stomach felt like the start of Rocking Roller Coaster at Disney.

It was awesome ... the ESP light flickering in the darkness as the car was barely holding traction.

Very cool experience ... got close to home and realized I was in Eco mode ...

Usually I switch to Sport as soon as Istart the car.

KEY08

Arrie

C280 Sport

Cold air is great for engines Simple as that. Imagine if you had the Bi turbocharged E550 With AWD. Sport Mode on. No A/C on too helps

KEY08

C280 Sport

Really? Most people say otherwise. Interesting! Why so? Sound? Feel of it?

cetialpha5

Cool air has more oxygen in it than hot air. So if you run a fixed air/fuel mixture, you get more power with cool air than hot air.

KEY08

thefisch

Very cool. Too bad I live in Florida. On the plus side, it was 80 and gorgeous today.

SteveE400

Ah, yes. . . but at least here in the Upper Rust Belt we get higher air density more often. That said, my turbo car doesn't care - it just keeps the waste gates closed until it hits target pressure.

kajtek1

Even if the car is 0.1 second faster, even with stop watch it is not measurable.
So we are talking 99% placebo effect here?
Than remember that dense air make bigger air drag.

cetialpha5

It's definitely measurable. Probably more accurate to say cold air typically has less water vapor than hot humid air. It's a standard phenomenon when flying. Hot summer weather a prop plane doesn't develop as much power and lots of times you hear of small plane crashes where the plane was overloaded for the temperature, the engine just doesn't develop enough power to lift off.

When I worked at a gas power plant, it was evident in the power output, hot summer days the plant struggled to do 270 megawatts, normally it was around 300, in the winter it could go as high as 340.

C280 Sport

Ya it was!

Arrie

Using the ideal gas law PV = nRT you can easily look into this.

Assuming the volume and pressure stay constant, like is the case with N/A engine we can write the equitation as n = (1/T) x (PV/R). In this formula (PV/R) stays constant as assumed above.

Now the temperature T is the absolute temperature and for 90 F it is 305.4 K and 40 F is 277.6 K

So the amount of air moles (n) at 90 F is n = (1/305.4) x (PV/R) and at 40F n = (1/277.6) x (PV/R)

The ratio of the amount of air moles is then 305.4/277.6 = 1.10, i.e. 40F air has 10% more material than 90F air in the same volume. This means 40F air has 10% more oxygen than 90F air meaning the engine control system can spray 10% more fuel to burn the oxygen. This should result in 10% more power with the same throttle opening.

With an engine with almost 400 hp it is roughly 40 hp increase in power and this should indeed be noticeable. In my car is certainly is. And some tunes advertise only about this magnitude power increase so if those are noticeable so should the effect of the lower air temperature also be.

Turbo engines are probably different and I don't know how the air temperature after turbo chargers is controlled but the max pressure is controlled with the waste gates and volume entering the engine should stay pretty much the same so if the air temperature drops the above calculation should somewhat apply to turbo charged engines too.

ChrisB

As the the thermodynamic equation predicts - if in actuality there is a 10% increase in power (considering 90 F air vs 40 F air) ... does that relate directly to 0 to 60 acceleration?

If 5 second run (that may be a common feeling for an E 550 driver - which is impressive enough) turns into a 4.5 second run ... that would probably produce noticeable physical sensations in the body. I believe that is what put the smile on my face.

More than a pure placebo effect. Although that was in play as well.

Arrie

Like I said in my post my car is noticeably stronger in cold weather. It is very easy to feel.

cetialpha5

Well you could always measure it with this butt dyno.

http://kalecoauto.com/index.php?main...&products_id=8

Johnny Rad

kajtek1

Things you can learn on the net

zeemob

After 45 minutes of driving.. at a traffic stop in Houston, TX

kajtek1

You have 76F at 8 AM in Houston?
How did you get the oil temp display?

zeemob

It was 7:13pm on 02/06/19 to be exact.

You can get the coolant temp + engine temp + current gear display + lap timer etc by activating the AMG Menu on the instrument cluster (even Non-AMG vehicles). Of course you will need MB SDConnect + Vediamo + some expertise.

Mud

Last year I tried to show my ditz neighbor why his cheap aftermarket "cold air intake" caused his car to perform worse not better.
It was just sucking in underhood air, and the aluminum tube acted like a big heat sink. I hooked up my scanner to show real time data. This was in Texas late summer.
Stock airbox and inlet IAT temp 96d F
Aftermarket air intake IAT temp 134d F
MAF sensor gm/sec reading increased with cooler air inlet temps, I figured due to denser air.
Short term fuel trim range also increased with the after market intake, I took it to be due to a leaner condition. I doubted the cone filter flowed any better than a good quality stock paper filter.
It was actually a hot air intake that made more noise.
I think cooler denser air is a good thing especially when its free as in outdoor temperature drop. The nice thing is that with computer controls the vehicle can take advantage of it!

ChrisB

TeeEl

My E550 takes off like a damn rocket then lurches like it hit the end of a bungee cord when it shifts. I'm not sure if it's due to transmission, ESC, whatever other reason. Some time I'll record my instrument cluster while doing this because I'm usually too concerned with keeping my eyes on the road to see what's going on.