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BMW 3-Series (E90 E92) Forum
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6MT shifting with AC on
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06-15-2007, 06:15 PM | #1 |
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6MT shifting with AC on
I normally shift around 2700-3000 rpm, but I noticed when the AC is on it becomes hard to shift smoothly at these rpms and I would have to go north of3500 rpm to help smooth the shifts out. Are you guys noticing the same thing? I know the AC puts extra load on the engine, but it should not be this noticeable on an engine this size.
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06-15-2007, 08:33 PM | #3 |
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I, too, notice that. But I notice it with other cars as well. I believe when the a/c is on, it's using a lot of juice from the surge compressor that's why.
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06-15-2007, 08:57 PM | #4 |
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Yes, especially if you "Max" out the A/C. I feel the power lost is more apparent when shifting from 1st to 2nd.
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06-16-2007, 12:53 AM | #7 |
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You know I never thought I would say this, but with this particular car and this particular auto tranny....
This car is better driving and more user friendly and for the most part faster with the Steptronic. It's almost as if this car was built around that tranny.
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06-16-2007, 06:22 AM | #8 | |
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In my old e36 m3 ...oh yeah, you felt it kick in even while at highway speeds...car would slow for a second when you turned it on, needless to say I rarely used the a/c. |
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06-16-2007, 03:32 PM | #11 | |
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Quote:
They need to make a/c run off the electrical system, not the engine. -Dan
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06-16-2007, 03:51 PM | #12 | |
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in this case the a/c will take the power from the generator that of couse will take the same power off the engine (becaming harder to spin as you request more current). Not only, since the generator has a 80% efficency you will loose ... after this your 'electric' A/c will require a compressor (another electric motor ...). Attaching the compressor directly to the engine is actually the most efficent option fdc
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06-16-2007, 03:54 PM | #13 |
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never noticed this....
i guess i usually shift higher than 3500 rpm....
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06-16-2007, 04:12 PM | #14 |
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I got the cdv delete. Now it shifts like a hot knife through butter. Even with the AC on
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06-16-2007, 06:12 PM | #15 | |
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-Dan
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06-16-2007, 09:12 PM | #16 | ||
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Quote:
AT usually gives up 10% to 15% of the engine power compared to MT as a result of powerloss in the torque-converter.
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06-16-2007, 11:15 PM | #18 | |
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with AC the way it is now, you have a certain amount of engine power that is required to turn the AC compressor if you had an electric AC compressor, you'd need electricity, which is made by the alternator, which is spun by the motor. So if you needed electric AC the alternator would draw more energy from the motor turning mechanical energy into electrical energy is not a %100 efficent process, so if you had an electrical AC compressor your engine would have to work harder than if you had a standard mechanical AC compressor |
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06-17-2007, 12:27 AM | #19 |
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i just tried to avoid the ac just because i know its going to change the car's performance
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06-17-2007, 12:54 AM | #21 |
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i noticed this with my ac on as well. but i figured since the ac was on it was normal. and sine everyone else is posting about it i guess it is.. i cant shift was smooth..
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06-17-2007, 01:36 AM | #22 |
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drive with window down =P
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