[jamesbeaumont]

I was wondering if anyone else on here has noticed how big a difference air temperature seems to make to the responsiveness of their cooper? Ive also noticed that its slower when damp/raining... I know its normal to have a bit of difference but the engine seems really sensitive

[Ant FR]

somebody never paid attention in chemistry did they.

Basically the colder the air the denser it is, therefore more oxygen per given volume. Therefore assuming the same volume of air enters the air intake you will have a bette burn, thus creating more power.

[KenL]

Quote: Originally Posted by Ant FR (original)

somebody never paid attention in chemistry did they.

Basically the colder the air the denser it is, therefore more oxygen per given volume. Therefore assuming the same volume of air enters the air intake you will have a bette burn, thus creating more power.

I thought you learned that in Physics, not Chemistry

Anyway, I am not sure you are completely correct?

Air density is based on air pressure is it not? The air pressure can be low or high when it is cold and warm?

In addition to this, James said his performance was worse when damp/raining.

TBH, I have not noticed any difference in performance when cold or wet. Should there be a difference in a normally aspirated car?

I am convinced though that my fuel consumption is worse by about 2mpg.

Perhaps this thread would be better answered if it were in the performance section.

[Goonery]

For the record, this explains it quite well. Its for Aero engines but the principle applies to any internal combustion engine.

ULPower : Engine Resources : ISA conditions

[jamesbeaumont]

Thanks guys, I understand the density variations with temp and moisture (from physics) I just havent noticed a difference so significant in other cars, damp conditions especially. I thought it could be something to do with an unusual filter shape/design, lack of air etc. Who knows!