Performance drain using A/C?

Coder335i · 07-20-2007, 06:07 PM

Has anyone seen any noticeable performance loss when using the A/C?

I know there is an additional load on the engine using the A/C, just not sure how much it should be and how noticeable. I would expect a car of this quality and price to handle this without issue.

Curious to know other's experiences..

DanMardik · 07-20-2007, 06:21 PM

I feel this as well, and it's normal. Regardless if you drive a ferrari or a Honda Civic. I'm not well versed into the specifics as to why so I'm not going to get into specifics.

STE92VE · 07-20-2007, 06:21 PM

Have had the A/C on auto since the day I took delivery. If there is a power loss, can't wait until cooler weather!

DanMardik · 07-20-2007, 06:23 PM

Quote:

Originally Posted by STE92VE

Have had the A/C on auto since the day I took delivery. If there is a power loss, can't wait until cooler weather!

AndrewAZ · 07-20-2007, 06:57 PM

Yep... Unlike the E46 M3 before I remember whenever I would drive that hard it would cut the A/C from taking power form the motor but of course the result was the car was miserable to drive in Arizona's hot summers and its hard not to drive the card hard, well for me not redlining every other light is hard..

I can spin the tires on my current E90 with the A/C off but when the A/C is on I have yet to do it.

John 070 · 07-20-2007, 07:09 PM

I think my 0-60 went to about 13.8 sec, but I got the ZAC premium air pkg. which I can also use to cool my house with the optional 7FL Carrier/Trane USB interface. The top speed is also under 100 because the compressor is mounted on my roof, but you can take it off in the winter mos.

Driver72 · 07-20-2007, 07:12 PM

Yes, there is a bit of a drag on when the A/C is on in normal driving.
But basically every modern car releases the A/C drive when a car is floored (goes full throttle).
Therefore, you should not lose any performance when going full throttle on your car even with the A/C on.

There is a "clutch" type mechanism that stops turning the a/c compressor at this point (full throttle application) so air will continue to blow, because of the fans but no extra power is being drawn from the engine. You should be at full power at this point.

STE92VE · 07-20-2007, 07:13 PM

Quote:

Originally Posted by DanMardik

garek · 07-20-2007, 07:14 PM

Every car I've ever driven has suffered a performance loss from A/C. This is quite common.

Driver72 · 07-20-2007, 07:20 PM

Quote:

Originally Posted by AndrewAZ

I can spin the tires on my current E90 with the A/C off but when the A/C is on I have yet to do it.

Your doing something wrong then.
Your A/C clutch will release at full throttle.
I can spin my minivans tires with or without the A/C on.

ejazbmw · 07-20-2007, 07:24 PM

i notice a bit of a difference, but i can careless its to hot to think about performance.

ToddMcF2002 · 07-20-2007, 07:36 PM

Quote:

Originally Posted by AndrewAZ

Yep... Unlike the E46 M3 before I remember whenever I would drive that hard it would cut the A/C from taking power form the motor but of course the result was the car was miserable to drive in Arizona's hot summers and its hard not to drive the card hard, well for me not redlining every other light is hard..

+100000000 it was a miserable feature. If I really wanted every ounce of power I could turn off the AC! Just great when you are wearing work clothes. :mad: Way too much electronice in general. Hated the software throttle and that silly power button but that is another topic altogether.

SunnyvaleCA · 07-20-2007, 07:37 PM

Running the A/C will also heat up everything under the hood: engine compartment, oil, radiator fluid, etc. When you are running with marginal gasoline such as California RFG II fuel, this may cause the engine timing to be cut back to limit precombustion, resulting in decreased power even if the A/C compressor is released.

achien · 07-20-2007, 08:03 PM

Quote:

Originally Posted by Coder335i

Has anyone seen any noticeable performance loss when using the A/C?

I know there is an additional load on the engine using the A/C, just not sure how much it should be and how noticeable. I would expect a car of this quality and price to handle this without issue.

Curious to know other's experiences..

With A/C on, I thought I was driving the '84 Hyundai Pony...

Driver72 · 07-20-2007, 08:22 PM

Quote:

Originally Posted by achien

With A/C on, I thought I was driving the '84 Hyundai Pony...

SE3P_to_E90 · 07-20-2007, 08:26 PM

Quote:

Originally Posted by achien

With A/C on, I thought I was driving the '84 Hyundai Pony...

Pony eventually grow up to be horses.

edgarj · 07-20-2007, 08:55 PM

Here's an article on the power loss due to AC. The dyno showed a loss of 11hp on a 3.0 Z4.

http://blogs.automobilemag.com/10071...ton/index.html

jhv · 07-20-2007, 09:04 PM

funny you should bring this up because whenever i want to "push" my car or whatnot, i always turn off the a/c and fan, lol
i thought i was the only one who did this

Driver72 · 07-20-2007, 09:48 PM

Quote:

Originally Posted by edgarj

Here's an article on the power loss due to AC. The dyno showed a loss of 11hp on a 3.0 Z4.

http://blogs.automobilemag.com/10071...ton/index.html

That's funny that the Z4 doesn't disengage the A/C compressor.
It even says in the article that "some" cars do that.
It's more like "most" cars these days.
Heck even that decades old Mercedes did.

Wonder if they ran the dyno without the A/C first and then with the A/C afterward. If so, the heat soak alone could of/would of caused a 11 hp drop.

They would of had to let the engine cool for 15-20 minutes at least before doing another run with the A/C on for this test to be valid.

I'd be surprised if a $45k sports car didn't disengage the A/C compressor at full throttle. I bet the 11 hp loss was simply because they did pretty much back to back runs and the Z4 was just heat soaked.

Anyone whose familiar with dyno tests knows you can lose that much hp between runs if you do the runs pretty much back to back.

533ogetnom · 07-20-2007, 10:12 PM

Quote:

Originally Posted by Driver72

Your doing something wrong then.
Your A/C clutch will release at full throttle.
I can spin my minivans tires with or without the A/C on.

where did you get that info, i know that the AC will decouple at higher RPMs to prevent it from exploding since its just a straight connection, but i havent heard of it doing this just because you go full throttle, infact i do regularyl on the highway in 6th and it stays cold

mayno · 07-20-2007, 10:52 PM

fwiw, i have my a/c pretty much about 80% of the time, and i don't experience any power loss. i've launched hard both w/ the a/c on and off, and i really can't tell the difference. both launched quickly and w/out hesitation.

if i were to do a 1/4 mile run or track the car, i'd obviously turn it off, but in normal day-to-day driving i can't notice the difference.

flush01 · 07-20-2007, 11:36 PM

when AC is on i feel clutch gets more jerky for some reason...

07-20-2007, 06:07 PM	#1
Coder335i Second Lieutenant 23 Rep 231 Posts Drives: 2007 - MB 335i Coupe Join Date: Apr 2007 Location: Florida iTrader: (0)	Performance drain using A/C? Has anyone seen any noticeable performance loss when using the A/C? I know there is an additional load on the engine using the A/C, just not sure how much it should be and how noticeable. I would expect a car of this quality and price to handle this without issue. Curious to know other's experiences.. __________________ //E92 Coupe - Monaco Blue/Saddle Brown, Gray Poplar//
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07-20-2007, 06:21 PM	#2
DanMardik Captain 17 Rep 729 Posts Drives: 08 INFINITI G37S Join Date: Dec 2006 Location: Irvine, CA iTrader: (0)	I feel this as well, and it's normal. Regardless if you drive a ferrari or a Honda Civic. I'm not well versed into the specifics as to why so I'm not going to get into specifics. __________________ *RIP 2007 335i Sedan*
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07-20-2007, 06:21 PM	#3
STE92VE STEVIL Empire 218 Rep 6,297 Posts Drives: Fast Join Date: May 2006 Location: Long Island, NY iTrader: (0)	Have had the A/C on auto since the day I took delivery. If there is a power loss, can't wait until cooler weather! __________________ 2007 E92 328i 6MT-Space Gray/Black Dakota/Gray Poplar w/heated seats-PCD 4/27/07 (SOLD) 2009 E90 328i xDrive 6AT-Space Gray/Oyster Dakota/Dark Burl Walnut w/ZPP,ZCW,Xenons-ED 4/17/09 - Redelivery 5/30/09 (SOLD) 2014 E84 xDrive28i 8AT-Alpine White/Black Nevada/Silver Matte w/ZMV,ZLP,494 - DD 3/14/14 (SOLD)
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07-20-2007, 06:57 PM	#5
AndrewAZ Major 137 Rep 1,243 Posts Drives: 335i Join Date: Jan 2007 Location: CA iTrader: (0)	Yep... Unlike the E46 M3 before I remember whenever I would drive that hard it would cut the A/C from taking power form the motor but of course the result was the car was miserable to drive in Arizona's hot summers and its hard not to drive the card hard, well for me not redlining every other light is hard.. I can spin the tires on my current E90 with the A/C off but when the A/C is on I have yet to do it.
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07-20-2007, 07:09 PM	#6
John 070 Lieutenant General 1705 Rep 14,829 Posts Drives: 335i cpe Join Date: Oct 2006 Location: ZSP/ZPP/ZCW iTrader: (0)	I think my 0-60 went to about 13.8 sec, but I got the ZAC premium air pkg. which I can also use to cool my house with the optional 7FL Carrier/Trane USB interface. The top speed is also under 100 because the compressor is mounted on my roof, but you can take it off in the winter mos.
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07-20-2007, 07:12 PM	#7
Driver72 Brigadier General 327 Rep 4,484 Posts Drives: 335i - to new owners now. Join Date: Dec 2006 Location: California iTrader: (0)	Yes, there is a bit of a drag on when the A/C is on in normal driving. But basically every modern car releases the A/C drive when a car is floored (goes full throttle). Therefore, you should not lose any performance when going full throttle on your car even with the A/C on. There is a "clutch" type mechanism that stops turning the a/c compressor at this point (full throttle application) so air will continue to blow, because of the fans but no extra power is being drawn from the engine. You should be at full power at this point.
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07-20-2007, 07:14 PM	#9
garek Second Lieutenant 10 Rep 287 Posts Drives: 09 E90 M3 DCT Join Date: Apr 2006 Location: Arizona iTrader: (0)	Every car I've ever driven has suffered a performance loss from A/C. This is quite common.
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07-20-2007, 07:24 PM	#11
ejazbmw blahhh 302 Rep 6,355 Posts Drives: 2014 M235I Join Date: Apr 2007 Location: NJ/NY iTrader: (7)	i notice a bit of a difference, but i can careless its to hot to think about performance.
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07-20-2007, 07:37 PM	#13
SunnyvaleCA Enlisted Member 0 Rep 36 Posts Drives: 1998 C43 AMG Join Date: Jun 2007 Location: Bay Area iTrader: (0)	Running the A/C will also heat up everything under the hood: engine compartment, oil, radiator fluid, etc. When you are running with marginal gasoline such as California RFG II fuel, this may cause the engine timing to be cut back to limit precombustion, resulting in decreased power even if the A/C compressor is released.
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07-20-2007, 08:55 PM	#17
edgarj Captain 32 Rep 815 Posts Drives: 335i e92 Join Date: Oct 2006 Location: San Marcos, TX iTrader: (1)	Here's an article on the power loss due to AC. The dyno showed a loss of 11hp on a 3.0 Z4. http://blogs.automobilemag.com/10071...ton/index.html
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07-20-2007, 09:04 PM	#18
jhv Lieutenant General 1699 Rep 17,304 Posts Drives: G80 M3 Join Date: Apr 2007 Location: Los Angeles iTrader: (1)	funny you should bring this up because whenever i want to "push" my car or whatnot, i always turn off the a/c and fan, lol i thought i was the only one who did this Last edited by jhv; 07-22-2007 at 05:22 PM..
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07-20-2007, 10:52 PM	#21
mayno Captain 72 Rep 613 Posts Drives: 2007 335i / 2018 BMW 430i Conv Join Date: Dec 2006 Location: So Cal iTrader: (0)	fwiw, i have my a/c pretty much about 80% of the time, and i don't experience any power loss. i've launched hard both w/ the a/c on and off, and i really can't tell the difference. both launched quickly and w/out hesitation. if i were to do a 1/4 mile run or track the car, i'd obviously turn it off, but in normal day-to-day driving i can't notice the difference.
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07-20-2007, 11:36 PM	#22
flush01 Major 46 Rep 1,419 Posts Drives: 33m@%#ing5 Join Date: Feb 2006 Location: toronto iTrader: (0)	when AC is on i feel clutch gets more jerky for some reason...
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