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why AC steals so much power ???

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Old Aug 24, 2003 | 09:36 PM
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why AC steals so much power ???

I hardy ever use AC , but in past few days it was just too humid , and I drove around town with AC on - the car felt sooooo sluggish !!!
my 93 Geo prizm Lsi (auto) with 118k feels the same AC on or off
the power loss on maxima is huge when compared to almost no power loss on 1.8L Geo ...
what is goin' on with 3.0 VQ ????

Nick.
Old Aug 24, 2003 | 09:50 PM
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Because a Geo has no power to lose.
Old Aug 24, 2003 | 09:58 PM
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Re: why AC steals so much power ???

Originally posted by nick
I hardy ever use AC , but in past few days it was just too humid , and I drove around town with AC on - the car felt sooooo sluggish !!!
my 93 Geo prizm Lsi (auto) with 118k feels the same AC on or off
the power loss on maxima is huge when compared to almost no power loss on 1.8L Geo ...
what is goin' on with 3.0 VQ ????

Nick.
because the AC compressor runs off the belt which takes power away from the crank.
Old Aug 24, 2003 | 10:12 PM
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Originally posted by iansw
Because a Geo has no power to lose.
I beg to differ !!!

the dang GEO weights 2200 lb and it's 1.8 liter is good for 115HP and 115 TQ - the car is very quick and nimble - I wish maxima was that nimble... plus the Toyota tranny always stays at the sweet power spot , unlike the maxima tranny which is always gear to high !!!

but seriously - there is a huge power loss with AC on VQ motor.

Nick
Old Aug 24, 2003 | 10:21 PM
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I dont really feel a loss
Old Aug 24, 2003 | 10:38 PM
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Originally posted by nick


I beg to differ !!!

the dang GEO weights 2200 lb and it's 1.8 liter is good for 115HP and 115 TQ - the car is very quick and nimble - I wish maxima was that nimble... plus the Toyota tranny always stays at the sweet power spot , unlike the maxima tranny which is always gear to high !!!

but seriously - there is a huge power loss with AC on VQ motor.

Nick

that's why you should have got a 5 spd.
Old Aug 24, 2003 | 11:32 PM
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I hardly ever turn off the AC, but the odd time that I have, I've never noticed any difference in power.
Old Aug 24, 2003 | 11:35 PM
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My maxima is nimble more nimble then any GEO ever produced

-matt
Old Aug 24, 2003 | 11:53 PM
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it may just be the humidity. I use my A/C most of the time here in Arizona where we have some dry heat, I don't feel a power loss it all. Well maybe just little but is not noticeable. I remember an old threat in which they said that the A/C takes 10HP when the compressor clutch is engaged.
Old Aug 25, 2003 | 12:06 AM
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5 spd, no difference.
Old Aug 25, 2003 | 12:11 AM
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Originally posted by Oblongshapes
5 spd, no difference.

I also agree with this. What makes a big difference is how many people are in my car.
Old Aug 25, 2003 | 12:12 AM
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Originally posted by maximaseefu



that's why you should have got a 5 spd.
Nick,

So.....when are we gonna start the conversion just let me know!
Old Aug 25, 2003 | 12:14 AM
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Originally posted by Oblongshapes
5 spd, no difference.
oh ya. I forgot to mention that!
Old Aug 25, 2003 | 12:19 AM
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i don't feel any power loss with AC on, but just little higher idle rpm
Old Aug 25, 2003 | 01:28 AM
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i don't feel any power loss with a/c on...

and also, if you're going WOT, the a/c compressor shuts off so you should still be running at full power
Old Aug 25, 2003 | 06:35 AM
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My car felt a little sluggish when I turn on my AC. I was driving in midtown NYC on a summer afternoon with two of my friends. Around 160 pound each including me. I turn on the AC and my car is not moving the way as before. I have to give a bit more gas to move it.

When my AC is on manual at 65 degree, I don't feel that cool. But when is on automatic at 65 degree, I felt the chill alot quicker. I don't know what's wrong, just a curious thought.

Max 96 GLE
Old Aug 25, 2003 | 07:08 AM
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the loss in power is a fact. It will work harder to cool depending on the variance between the outside temperature and what is inside.
Old Aug 25, 2003 | 07:25 AM
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On a really hot day.. when i have my AC on my car is slugish as well. I mean i have to floor it to get some good acceleration. Would pulleys help?
Old Aug 25, 2003 | 07:39 AM
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I can feel the difference in performance with the AC on, but it's not a HUGE difference. The VQ just doesn't feel as smooth or as willing to rev. I've accidently left my AC on at the track and it slows me ~.1 and 1mph. Nothing huge, but it does slow you down somewhat. IU have a 5 speed so the initial lag probably doesn't feel as bad.


Dave
Old Aug 25, 2003 | 07:57 AM
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Just do what i did and the maxima wont be sluggish and your power to weight will be better than a geo
Old Aug 25, 2003 | 07:58 AM
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I don't feel it. My car seems to run strong even with a heavy load. Great car for travelling the roads.
Old Aug 25, 2003 | 10:46 AM
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I would say a 4 cyl engine would feel more when the AC compressor engage...IMO depends if the car is properly maintained or needs a tune up. Of course is going to loose pwer due to the load on the engine. If you cahnge the pulley,you may see an improvement ,but the cooling when the car idles ,may not be as good. Look at Motorvate web site and check the UDP replacement.
Old Aug 25, 2003 | 06:49 PM
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Originally posted by ivolley


Nick,

So.....when are we gonna start the conversion just let me know!
as soonest I get all the parts , i also want the LSD .
right now I'm taking engine rebulilding at local college - looking forward to expand my limited automotive knowledge !!!




Just found out from edmunds.com that my 97 SE black on black fully loaded w/o cd changer with 125k is worth $7400 with auto tranny
with 5 speed is still worth 7200 !!!
hellllsss yeaaaa !!!!

BTW does anybody took engine rebuilding recently and used -Automotive engine rebuilding by James G. Hughes
and still have that book stashed in the closet - let me buy it !!!


back to the original thread - car is back to normal - trunk full of chit and huge toolboox plus 90' temps made such a difference.

Nick.
Old Aug 25, 2003 | 07:00 PM
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Originally posted by nick


as soonest I get all the parts , i also want the LSD .
right now I'm taking engine rebulilding at local college - looking forward to expand my limited automotive knowledge !!!




Just found out from edmunds.com that my 97 SE black on black fully loaded w/o cd changer with 125k is worth $7400 with auto tranny
with 5 speed is still worth 7200 !!!
hellllsss yeaaaa !!!!

BTW does anybody took engine rebuilding recently and used -Automotive engine rebuilding by James G. Hughes
and still have that book stashed in the closet - let me buy it !!!


back to the original thread - car is back to normal - trunk full of chit and huge toolboox plus 90' temps made such a difference.

Nick.
i always have the ac on and i do feel the power lost. the last few nights have been cool around here (68) and the car feels much stronger now.
Old Aug 25, 2003 | 08:06 PM
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On my auto, the power loss is very noticeable with AC on, i just got a pulley installed and it helps alot, the AC is the same coldness though...
Old Aug 25, 2003 | 10:02 PM
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Is it me or is everyone forgeting the principle of a compressor. It creates cool by getting hot. So, since its in the engine bay it makes the area hotter, thus robbing power.
Old Aug 25, 2003 | 11:05 PM
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Ah no. The AC compressor is a heat pump yes, but the reason is robs power is because nothing is for free. It takes energy to run the compessor(ie.. about 5-6 hp).

Originally posted by broaner22
Is it me or is everyone forgeting the principle of a compressor. It creates cool by getting hot. So, since its in the engine bay it makes the area hotter, thus robbing power.
Old Aug 26, 2003 | 07:18 AM
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Originally posted by Dave B
I can feel the difference in performance with the AC on, but it's not a HUGE difference. The VQ just doesn't feel as smooth or as willing to rev. I've accidently left my AC on at the track and it slows me ~.1 and 1mph. Nothing huge, but it does slow you down somewhat. IU have a 5 speed so the initial lag probably doesn't feel as bad.


Dave
The ECU disengages the clutch in the AC pully when at WOT. It shouldn't make any difference at the track.
Old Aug 26, 2003 | 07:48 AM
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Originally posted by ejj


The ECU disengages the clutch in the AC pully when at WOT. It shouldn't make any difference at the track.

Has this been proven or has it just been assumed? The reason I ask is because my Max blows cold air at WOT. On my old Z28, you could actually feel the compressor disengage at 4000rpms and the air went from icey to warm and humid and once you let off and the rpms came back around 4000rpms, you felt it kick on again.


Dave
Old Aug 26, 2003 | 09:15 AM
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My maxima will blow cold air for a few min after turning off the AC(but keeping the fan on). Try it. Since you aren't(or shouldn't be ) at wot for more than a few seconds anyway, that's what you are experiencing

Originally posted by Dave B



Has this been proven or has it just been assumed? The reason I ask is because my Max blows cold air at WOT. On my old Z28, you could actually feel the compressor disengage at 4000rpms and the air went from icey to warm and humid and once you let off and the rpms came back around 4000rpms, you felt it kick on again.


Dave
Old Aug 26, 2003 | 09:23 AM
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Originally posted by Dave B



Has this been proven or has it just been assumed? The reason I ask is because my Max blows cold air at WOT. On my old Z28, you could actually feel the compressor disengage at 4000rpms and the air went from icey to warm and humid and once you let off and the rpms came back around 4000rpms, you felt it kick on again.


Dave

Mine does that too. Usually after 5K - 5.5K it's when the humid air comes out. But If I floor it and don't rev up that high I still get very cold air.
Old Aug 26, 2003 | 10:42 AM
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Well this is what i know. It might either be the weight, the heat generated or the drain on the engine of the AC system, but i know without it the car feels faster at WOT and at other throttle. Basically is just hurts the car's performance in some way or another.
Old Sep 4, 2003 | 06:36 AM
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I've a 95 se w/5spd and climate control, and I do feel some power loss w/ the ac on. If just the fan is on, or the heat(econ), then there is no difference, but on auto it is noticeable
Old Sep 4, 2003 | 10:43 AM
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Originally Posted by Dev
i don't feel any power loss with a/c on...

and also, if you're going WOT, the a/c compressor shuts off so you should still be running at full power
I find I don't accelerate as quickly (non-WOT) with the A/C on. It's just the butt-dyno so nothing really quantitative about that. So, I prefer to sweat a bit for more power (& reduced gas usage).
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