BMW M3 Forum (E90 E92)

BMW Garage BMW Meets Register Search Today's Posts Mark Forums Read


Go Back   M3Post - BMW M3 Forum > M3 (E90 / E92 / E93) > General M3 Forum (E90 + E92 + E93)
 
European Auto Source (EAS)
Post Reply
 
Thread Tools Search this Thread
      08-14-2018, 03:55 PM   #1
Merlin_83
Merlin
Merlin_83's Avatar
United_States
130
Rep
423
Posts

Drives: 2012 BMW M3 w/ZCP 6MT
Join Date: Feb 2014
Location: United States

iTrader: (0)

Angry She no likey the heat - hot, hot weather and A/C

Greetings,

It's been 96-100 degrees Fahrenheit and very dry the last 2 weeks. I try to never run the A/C, but had to with the high temps.

In stop and go traffic the car feels so sluggish has F#$& ! On long runs not as much. What's the horse power penalty running either the air conditioning on MAX or AUTO (set to 60 degrees) ?

The car just feels like it doesn't like the high temp in general under 40 mph. At higher speeds it's better with ducted air flowing to the radiator, A/C condenser coil, oil cooler, transmission cooler, err...power steering cooler

Thank you,

Merlin
__________________


2012 BMW M3|ZCP|6MT|Navi|Cold Weather Package |Premium Package|
Appreciate 0
      08-14-2018, 04:00 PM   #2
Hurricane Beefaroni
Somebody Toucha My Spaghet
Hurricane Beefaroni's Avatar
2269
Rep
511
Posts

Drives: E92 M3
Join Date: Apr 2016
Location: Los Angeles

iTrader: (1)

Whats the under tray on the front of your car like? IIRC if it's beat to shit, it can cause your car to run hot.
__________________
lol made you look
Appreciate 0
      08-14-2018, 04:25 PM   #3
SkiFly01
New Member
SkiFly01's Avatar
United_States
9
Rep
27
Posts

Drives: '11 M3 comp pkg
Join Date: Jun 2018
Location: Nashville, TN

iTrader: (0)

The AC compressor is quite efficient, I've run it when I lived in FL, when I picked the car up in Dallas and drove back, it causes very little parasitic loss. It was not uncommon for me to see 105+ temps on the roads around Tampa/Orlando and the AC not skip a beat and stay cold, however those higher air temps just heat soak the entire car and I felt that total heat soak is what just makes any car feel sluggish, not necessarily the drag of running a compressor.
__________________
-Kai
Appreciate 0
      08-14-2018, 05:11 PM   #4
wyatth
Captain
239
Rep
703
Posts

Drives: E90 ZCP
Join Date: Dec 2007
Location: Bay Area

iTrader: (0)

^ Agreed, I think heat soak just makes a car sluggish. E.g., AC off at 100F still feels slower than AC off and ripping it at 50F. I don't notice a difference with AC on, and I've also read that the AC and alternator are disconnected at WOT anyway.
Appreciate 0
      08-14-2018, 05:18 PM   #5
UPSROD
Major
418
Rep
1,308
Posts

Drives: 2013 E92 M3
Join Date: Jul 2015
Location: Richland, Wa.

iTrader: (2)

Garage List
2013 BMW M3  [5.00]
NEVER running the AC will cause the seals to fail!
Appreciate 0
      08-14-2018, 05:41 PM   #6
XKxRome0ox
e90noob
United_States
310
Rep
905
Posts

Drives: '08 E90 M3
Join Date: Mar 2012
Location: Los Angeles, CA

iTrader: (3)

Quote:
Originally Posted by Merlin_83 View Post
I try to never run the A/C, but had to with the high temps.

In stop and go traffic the car feels so sluggish has F#$& ! On long runs not as much. What's the horse power penalty running either the air conditioning on MAX or AUTO (set to 60 degrees) ?
so you go from one extreme (never running the A/C) to the other (MAX A/C) ...
you should set it to a moderate 70-74 degrees and use the A/C more regularly
__________________
2008 E90 M3
Appreciate 0
      08-14-2018, 05:44 PM   #7
serranot
First Lieutenant
serranot's Avatar
111
Rep
362
Posts

Drives: 2011 E90 M3 6MT
Join Date: Mar 2011
Location: Rockville, MD

iTrader: (0)

Garage List
2011 BMW E90 M3  [5.00]
Warm air is less dense. The car will always be more sluggish in hot weather.

Not running the a/c might get you 8-12 hp more. Hardly worth suffering for that.
Appreciate 1
Timujin113.50

      08-14-2018, 06:55 PM   #8
wyatth
Captain
239
Rep
703
Posts

Drives: E90 ZCP
Join Date: Dec 2007
Location: Bay Area

iTrader: (0)

Regular use (once per month to a few times per year?) immediately followed by non-AC vent air flow before powering down is the best way to extend the life of the HVAC system. But that's not really the question here.
Appreciate 0
      08-14-2018, 07:52 PM   #9
elim11
Major
336
Rep
1,268
Posts

Drives: e90m3
Join Date: Apr 2008
Location: irvine/sf

iTrader: (13)

Under WOT I believe ac disengages...

You are just probably experiencing hot IAT.

You should turn the heater on max. Race cars do that to cool the engine. Lol
__________________
Appreciate 0
      08-14-2018, 09:02 PM   #10
Richbot
Brigadier General
1161
Rep
4,168
Posts

Drives: Jerez Black E90
Join Date: Sep 2007
Location: STL

iTrader: (3)

Its pulling timing
Appreciate 1
94jedi216.00

      08-15-2018, 06:58 AM   #11
DSilk
Major
United_States
532
Rep
1,160
Posts

Drives: 2008 BMW M3 Coupe
Join Date: Jun 2015
Location: South Florida

iTrader: (0)

Garage List
2015 Jaguar XJ  [0.00]
2015 Jaguar XF  [0.00]
2014 VW GTI  [0.00]
2008 BMW M3 Coupe  [0.00]
2007 VW Passat 2.0T  [0.00]
With my e46 M3 I could notice a real difference in acceleration with the A/C off vs. on. With my e92 M3 the difference is negligible. I leave it on (in South Florida it does get used year-round).
Appreciate 0
      08-15-2018, 09:16 AM   #12
SkiFly01
New Member
SkiFly01's Avatar
United_States
9
Rep
27
Posts

Drives: '11 M3 comp pkg
Join Date: Jun 2018
Location: Nashville, TN

iTrader: (0)

Agree with DSilk, a total crap car can be sold in FL for sooo much more because in the description they have the two words everyone is looking for, "Working AC".
__________________
-Kai
Appreciate 0
      08-15-2018, 10:35 AM   #13
Merlin_83
Merlin
Merlin_83's Avatar
United_States
130
Rep
423
Posts

Drives: 2012 BMW M3 w/ZCP 6MT
Join Date: Feb 2014
Location: United States

iTrader: (0)

Thanks guys !!

There's been some good advice, perspective and recommendations so far. And I think the best advice moving forward is putting the A/C setting to the AUTO mode and set to more moderate 68 or 70 F.

The heat soak thing also makes sense as I can tell even not running the A/C on hot, hot days the car just 'feels' slow. Not to digress the original topic but in reference to heat and air densities I know aircraft jet engines have to be 'de-rated' for certain conditions i.e. high and hot.

An example is a jet aircraft heavily loaded with fuel and payload taking off at Denver or other high elevation cities on a dry day. Air density is much less and the pilot has to de-rate take off thrust less than 100%. This done to minimize exhaust gas temperature [EGT] from being to high. Cars with turbocharges and inter-coolers allow the charge air to be cooled by the air-to air or air to water inter-cooler this has the affect of dropping temperatures to have denser [colder] and higher mass air. Basically more readily available oxygen. BMW takes it a step further buy dumping water into the fuel/air mixture, which is crazy when I think there adding water - But then I guess water injection aside from inter-cooling has been around for years in the hot rod community.

I may have stated some of that wrong so if there are any aerospace/aircraft engineers, please update or correct what I stated.


Thanks,
Merlin
__________________


2012 BMW M3|ZCP|6MT|Navi|Cold Weather Package |Premium Package|
Appreciate 0
      08-15-2018, 12:29 PM   #14
serranot
First Lieutenant
serranot's Avatar
111
Rep
362
Posts

Drives: 2011 E90 M3 6MT
Join Date: Mar 2011
Location: Rockville, MD

iTrader: (0)

Garage List
2011 BMW E90 M3  [5.00]
Well, derating is more of specifying a maximum power setting at less than max rated power to prolong its life, e.g., piston engines in a helicopter. This has the added benefit of being able to sustain max power higher up. Like if BMW derated the S65 to 300 horses. Obvi, you would be able to maintain that HP over a lot of altitudes and temps.

Your examples are more along the lines of not being able to use rated power because of another factor, such as temp limits. That certainly has the effect of derating it for that moment in time but it's not the normal usage of the term, derating applying beyond specific situations.

The bottom line is, all other things being equal, hot air is less dense (much like having a car at altitude). Less dense air makes less power.
Appreciate 0
      08-15-2018, 12:34 PM   #15
Z K
Brigadier General
Z K's Avatar
United_States
1150
Rep
4,480
Posts

Drives: E90 M3, B8.5 A4
Join Date: Jul 2011
Location: San Francisco

iTrader: (3)

Quote:
Originally Posted by pasghetti View Post
Whats the under tray on the front of your car like? IIRC if it's beat to shit, it can cause your car to run hot.
+1

I had a cracked undertray and for a little while I ran without it while I awaited a replacement. The car ran much hotter without the undertray - you can actually see higher temps on the gauge cluster temp reading. After I put on the new undertray, it was back to normal.
__________________
Auto Detailing Enthusiast!
Appreciate 0
      08-15-2018, 04:30 PM   #16
94jedi
First Lieutenant
216
Rep
390
Posts

Drives: 2008 e90 M3 | 2004 E46 M3
Join Date: Oct 2014
Location: United States

iTrader: (0)

high IAT's = timing pull. it sucks but that's the hot summer.
__________________
Alpinemss Tuned | MS Stage 2 Intake | MS Pulleys | Akrapovic Evolution Exhaust
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


All times are GMT -5. The time now is 02:40 AM.




m3post
Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST