[rsmallwo]

Hi All,

My 335d seems not quite as rapid as it usually is, its still rapid but while the weathers been hot I've noticed that when I "gun it" the world is still in shape and focus, I'm used to it starting to go blurry!!!!

I'm thinking that the combined extra load on the air con compressor and the slight decrease in air density due to the heat means I'm not getting quite the same power as when its cold.

Anyone else finding this?

I did have my turbo boost hose replaced by BMW just as the hot weather started and did wonder if they had reset my ECU and lost my remap
http://www.e90post.com/forums/showth...=281232&page=6

Hopefully I'm just worrying for nothing

[zltm089]

My one is running ok in London....;-)

[acerboo]

always run better when its cold as cold air is denser

[beemerbird]

Certainly does dull it as acerboo said, and turbo engines more so in my experience.

Bit like me, I don't fair well in this heat sorry to say.

[yatin c]

would definately agree. my 335i isnt as sharp once external temp gets over 20 degrees c. also temp gauge is at 120 - usually sits at 110. it hates london in this weather!

yatin

[shane55]

Yea I would agree my 330d today seemed a bit lazy in 26.0 degrees heat... I will go for a blast later in the cool evening to see if she's ok! I think when you accelerate fairly quickly the ECU drops out the air con compressor to prevent damage during hi-revving acceleration and not to allow it to zap some 4 horsepower from the engine at crucial overtaking moments!!!

[dxb335d]

Cars deffo will have affected performance in this weather. In start stop traffic you will have heat soak. Which can affect performance also.

Ive seen this at the drag strip. Cars loosing 2-3MPH at the end of the run due to it.

[HighlandPete]

Heat soak is a bigger issue than most believe, it takes a bit of constant driving to get rid of it as well, once soaked. So any hard acceleration from a 'stop start' situation will be more noticeable, than the same acceleration from running through the air at the same ambient temperature.

HighlandPete

[jvowles]

As mentioned previous - you will drop power due to the air density changing (decreasing) with ambients.

The power loss will vary engine to engine (realistically 20ps or so), however on the plus side your car would have lost aerodynamic drag in the warmer ambient air...

[Outlaw 06]

Originally Posted by acerboo

always run better when its cold as cold air is denser

+1. Warmer air = lower air density = decreased performance.

[chasealex]

On the plus side, you get noticeably better economy in the heat than in the cold.

[jvowles]

Originally Posted by chasealex

On the plus side, you get noticeably better economy in the heat than in the cold.

probably true on short journeys - but it should be the same if not better, if the tyre pressures are up, on longer journeys?