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Model specific boards => Golf mk6 => Topic started by: matchboy on 21 May 2010, 11:28

Title: Air Con on leading to power loss?
Post by: matchboy on 21 May 2010, 11:28
Poser for you chaps and chapesses - with the mk4 gti when you had the air con on there was a severe loss of power when accelerating; in the mk5 gti there was a slight loss of power also.  anyone tested it in their mk 6 gti yet?  i had a go this morning and i felt that under hard acceleration i felt a small loss in power.  this may be all in my mind though - any thoughts therefore?
Title: Re: Air Con on leading to power loss?
Post by: AlanD on 21 May 2010, 11:30
Its common on all cars to loose some power when running the AC. This is isnt just on VWs.
Title: Re: Air Con on leading to power loss?
Post by: matchboy on 21 May 2010, 11:34
yeah i know, i was just referring to gti's.  i was just wondering if anyone had noticeable loss on their mk6 gti's?
Title: Re: Air Con on leading to power loss?
Post by: scotland67 on 21 May 2010, 11:49
I leave the air con on all the time. There is surely enough power on a mk6 GTI to cpe with a small power loss.
I can't imagine one would even notice it.
Title: Re: Air Con on leading to power loss?
Post by: FroGTI on 21 May 2010, 11:57
I've tested it, but couldn't feel any difference.
Title: Re: Air Con on leading to power loss?
Post by: Rigman on 21 May 2010, 13:28
I would guess that a typical car AC compressor would absorb about 2-3hp, so that's less than 1½% of the power available at the flywheel. So I very much doubt you would notice it.

Mk 6 GTI, 3 Door, Manual, Carbon Grey, 18" Monza Shadows, RCD510 with Dynaudio + DAB, Xenons, Winter pack, Storage pack, and Mudflaps
Title: Re: Air Con on leading to power loss?
Post by: matchboy on 21 May 2010, 13:35
cool, nice one chaps  :smiley:
Title: Re: Air Con on leading to power loss?
Post by: Ess_Three on 21 May 2010, 13:40
I would guess that a typical car AC compressor would absorb about 2-3hp, so that's less than 1½% of the power available at the flywheel. So I very much doubt you would notice it.

I'd guess that's about right...possibly a 1 MPG difference too, at worst.
Incidentally, using cruise control has at least the same affect on MPG, but obviously not on performance.

Does the VW air-con cut off on full throttle like many other systems do?
If so, you'd not feel the difference anyway.
Title: Re: Air Con on leading to power loss?
Post by: matchboy on 21 May 2010, 14:11
nope i've not noticed it turn off at anytime, once its on its on.  as long as i'm not losing masses of power (which is what i would expect) that's all i care about, i know it will reduce my fuel consumption but if i was worried about that i wouldn't drive the way i do!   :evil:
Title: Re: Air Con on leading to power loss?
Post by: Ess_Three on 21 May 2010, 15:10
nope i've not noticed it turn off at anytime, once its on its on.  as long as i'm not losing masses of power (which is what i would expect) that's all i care about, i know it will reduce my fuel consumption but if i was worried about that i wouldn't drive the way i do!   :evil:

Same here...my air con is on Auto and will remain there, and I'll use the cruise whenever I fee like it.
VW make a car for those who want 50 MPG....and it's not a GTI!
Title: Re: Air Con on leading to power loss?
Post by: matchboy on 21 May 2010, 15:24
agreed!  those who want speed get the gti, those who don't and want mpg get a gtd!!  :wink:
Title: Re: Air Con on leading to power loss?
Post by: FroGTI on 21 May 2010, 17:17
agreed!  those who want speed get the gti, those who don't and want mpg get a gtd!!  :wink:

I drove past a (parked) GTD this morning and felt hugely superior :laugh:
Title: Re: Air Con on leading to power loss?
Post by: Keithuk on 22 May 2010, 15:59
Aircon uses about 3-5 bhp off the engine depending on which engine and aircon you have. I haven't noticed any power loss on my GTD but I can see it uses more fuel when switched on. Cruising on a motorway at 70mph the MFD shows 54.6mpg. Switch the aircon on and it slowly drops to 49.5mpg. Switch it of and it slowly goes back to 54.5mpg.  :wink:
Title: Re: Air Con on leading to power loss?
Post by: RickS on 24 May 2010, 07:29
Poser for you chaps and chapesses - with the mk4 gti when you had the air con on there was a severe loss of power when accelerating; in the mk5 gti there was a slight loss of power also.  anyone tested it in their mk 6 gti yet?  i had a go this morning and i felt that under hard acceleration i felt a small loss in power.  this may be all in my mind though - any thoughts therefore?

I don't know the precise power consumption of the climate control [the a/c compressor part at least] on the MK6, but on a Saab I had some years ago it used 15BHP to drive the a/c compressor [rolling road test], so you might notice it. Especially on hot days when this will be in almost constant use you also get a small additional drop in engine power due to hot ambient air not being as dense as cold air leading to a smaller mass of gas per "bang" in the engine.
Title: Re: Air Con on leading to power loss?
Post by: Steve30 on 24 May 2010, 07:32
agreed!  those who want speed get the gti, those who don't and want mpg get a gtd!!  :wink:

I drove past a (parked) GTD this morning and felt hugely superior :laugh:

You need to come up next to mine Frog , i am pritty sure your going to feel less than :grin:
Title: Re: Air Con on leading to power loss?
Post by: am1w on 24 May 2010, 08:02
I drove past a (parked) GTD this morning and felt hugely superior :laugh:

Careful Froggy: Steve has got more 'twist' with his GTD and he might wring your neck! :evil: :laugh:
Title: Re: Air Con on leading to power loss?
Post by: Keithuk on 24 May 2010, 16:39
I was doing a bit of research into the power used to drive the compressor. I didn't find any but I found Air conditioning for Cars (http://www.airconditioningforcars.co.uk/ACpage01.htm) with a link to Does the AC use extra petrol? I still don't agree with what they say. If the driver turns the AC off and opens the windows to cool down they say there is more air drag from the open windows than the power used to drive the AC. I'm not saying that the air drag will not cause a resistance but the compressor running will cause more.

Anything being driven by the engine uses the engine power. Using any electrical loads will make the alternator work harder which slows the engine down absorbing engine power.  :wink:
Title: Re: Air Con on leading to power loss?
Post by: Jimble on 24 May 2010, 17:01
Regardless of what the experts say, you can definatley 'feel' a difference when the ac is on, how much power is lost if any i have no idea.
I even notice the extra vibration through the pedals when the compressor is running, but i don't really care about any of it cos i'm nice and :cool:
Title: Re: Air Con on leading to power loss?
Post by: matchboy on 24 May 2010, 19:16

I even notice the extra vibration through the pedals when the compressor is running,

so that's what that is!!!!!  i thought something was wrong with my car!  cheers mate for clearing that one up!
Title: Re: Air Con on leading to power loss?
Post by: R32UK on 24 May 2010, 19:22
I have to say I can very clearly notice the loss of power. I dont use my ac at all.
Title: Re: Air Con on leading to power loss?
Post by: am1w on 24 May 2010, 19:36
I could not possibly comment as my average speed on my daily commute is approximately 9 mph. :sick:
What I can say is that the Climate Control keeps me comfortable during this hellish journey. For this I am truly grateful. :rolleyes:
Title: Re: Air Con on leading to power loss?
Post by: matchboy on 24 May 2010, 21:19
so after a few days testing with climate control  :laugh: on solidly, i can defo notice a loss of power.  not enough to annoy but certainly enough to make me think twice in situations where i may overtake.  also, interestingly enough i'm noticing a 6 mpg loss in consumption in my normal journey to work which is quite a lot and more than i would expect.  saying that, i'll take this rather than be hot!  :smiley:
Title: Re: Air Con on leading to power loss?
Post by: ub7rm on 24 May 2010, 23:25
Mk5ers views so might not be entirely valid but yeah you do notice the engine feels as if its held back a bit and the mpg certainly drops a bit with the compressor running.

I subscribe to the theory that at town speeds its more economical to have the window open than the ac on but at higher speeds the ac is the better option.