yogibear458

What a big difference 10C ambient temp makes to the performance. Steptronics shifts gear faster and the car goes much quicker! We had a hot spell in late June and temp was around 30C+ with fairly high humidity. The car was a big sluggish... floor the go pedal and the tach climbs 'slowly' and didnt feel like 325horses.

Temp has dropped to the low 20s in recent days and the car feels quicker. But kickdown isn't the same as pre 16.2 update.

I thought big displacement engines are not as susceptible to ambient temperature.

Maybe I'm more used to the speed now than when the car was new.

Wiss545

i donot think temperature has an effect on the engine,

where i live average temperature during the day 42C, thou i rarely drive my 545 manual but everytime i push the cash i got the same fantastic feeling of acceleration


Regards
Wiss545

Edlee

I believe temperature has a huge effect on the car's performance. A friend and I both experienced problems previously when the temp here hit 36.5 degrees C. The car went sluggish, was hesitant when pulling off and was jerky during idle. Returned back to normal in the evening.

E60Speed

The ECU looks at the air temp to help determine fueling, since 1 litre of hot air has less oxygen than 1 litre of cold air

Drive the car in the middle of a very hot day, then wait till late that night when the temp has droped a lot and go drive - HUGE difference

Wiss545

I believe than that the cars which are shipped to Hot countries are modified. because if high temperature will effect the performance my car will Hault and never leave it is place

MaxBuck

Of course engine performance is affected by ambient temperature. BMW engineers are great, but they cannot repeal the basic laws of thermodynamics.

mixterk

Colder air into the engines intake is better for performance than warm. Thats why when you buy and upgraded induction kit and air filter it comes with a tub that seperates the intake from the warm engine bay air and has it aimed at the colder air from outside.....hope that makes sense. So better when cooler

EBMCS03

But man... a N/A engine would still be affected "THAT MUCH" that you can feel the difference... especially 325hp?? I understand if it was forced induction with a turbo or S/C and only 150HP then ya you'll feel the difference. Ya it'll have an impact but you're not suppose to feel it but what do I know...

wolverine

Horsepower is very sensitive to temperature, and barometric pressure. SAE horsepower ratings utilize a correction factor for temperature and pressure. Basically your engine is rated at an ambient temperature of around 30 deg C. Hotter than that and you will produce less HP. In colder conditions your engine will produce more HP. You may also notice a difference when the barometer is very high (higher HP), or very low (lower HP). I would guess you're just feeling the higher HP due to the colder temperatures.

As an example, let's say you bring your car in for a test. Suppose your engine is running an actual 325 hp. If you test it on a day that is 30 deg C, then you should actually record just about 325 hp. Let's say the temperature dips to 20 deg C, and you bring it in again for a test. Your engine will be developing 332 HP because of the lower ambient temperature. That's a difference of 7 HP just from a 10 deg C drop in temperature. Your SAE horsepower rating is still the same 325, because of the correction factor.

Slight changes in barometric pressure will have the same type of effect. So if you look at a Dyno graph, make sure it's SAE 'corrected' horsepower. Otherwise you can't really compare the results to anything. Also, any good car test will give at least the temperature and possibly the barometric pressure since they have a significant effect on acceleration times.

EBMCS03

Ya I know that but actually "feeling" the difference of 7Hp is sensitive... Kinda little harder in a higher output engine.