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BMW 3-Series (E90 E92) Forum
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How much power do we lose when its hot outside?
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07-07-2007, 12:37 PM | #23 |
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I live in AZ where temps lately have been 115°+ and from spring to summer I have noticed a significant decrease in power. The heat coupled with the parasitic effect of the A/C definitely hinders the pavement peeling here in the desert.
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07-07-2007, 01:26 PM | #25 | |
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Basically, heat sucks for turbo cars. Hotter air is less dense air. Difficult to calculate the exact loss, but who really cares? |
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07-07-2007, 01:34 PM | #26 |
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My car did 275whp on the dyno in 95 degree heat... (uncorrected)... I only lost 2 hp on the 2nd and 3rd run because they were only a few seconds apart, and the car was heatsoaked.
I would say that the loss is minimal until you get pretty high above that. |
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07-07-2007, 01:52 PM | #27 | |
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Those with experience tuning and dynoing a car through various incremental HP upgrades get a feeling for how much more power the car is producing simply by way of its acceleration. On a hot day, they might notice that the acceleration is back to was when making X HP. Given that less than 10HP is not very noticeable, someone experienced with modding their car could tell you, probably within 10HP, what the negative or positive affect of ambient temp was.
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07-07-2007, 06:52 PM | #28 |
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Just a gut feel, but the power difference between 75 degrees and 20% humidity and 95 degrees and 90% humidity is very noticable.
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07-09-2007, 09:20 AM | #29 |
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It's because the air is compressed by the turbos. The hot, compressed air is less efficient than hot air that is not compressed (cooler, more dense).
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07-09-2007, 12:22 PM | #30 |
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07-09-2007, 12:34 PM | #32 |
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So the dyno fan blew air to your IC that was just slightly warmer at the last run. Heatsoak hits already before the end of the first dyno run. IATs are thus not much different between the runs. As the ambient temps are close to each other across the runs, your experiment does not tell much about ambient temps effect.
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