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Discussion Starter #1
First, I did a few searches and I got all kinds of information I wasn't looking for, so please forgive me if this thread question has been covered.

My question is a more general technical question regarding all cars and airconditioning, but I am also curious how it will effect the Solstice. From a previous thread, the entire airconditioning unit assembly in the Solstice weighs about 60 lbs, which will help slow down the car slighty by adding weight.

But what about with the airconditioner (compressor) running? How much HP does this suck from the engine? I'm assuming the internal blower fan won't take anything, but I believe the compressor (while actually running) does. I know it used to bog down my 1974 Cutlass with a 350 Rocket engine a little. I was told a long time ago that compressors rob as much as 30 HP while running. But some people here have said that "California Cruzin'" with the top down and the air on doesn't cost them anything. 30 HP sounds a little much to me, but I can't believe it doesn't take some.

So have things changed with more modern airconditioners and engines, or does it still rob HP with it running, and if so, how much?
 

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No way any current ac system will rob 30hp.

Most ac systems now have automatic clutches for the compressor that disengage at full throttle. Every GM car I own has that feature. I have no worries that the Kappa cars are the same. When it disengages I'm sure it takes less than 1/10 hp to have the ac pulley spinning.
 

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i understand your concern. i really felt it in my neon. but the disengaging clutch really helped.you are going to kill me for this but my prius has electric ac. yup and electric power steering. pretty neat so that neither one affects the cars power ( or some would say lack thereof) ;)
fred from nashville probably waiting forever at this rate
 

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mrfredsporty said:
i understand your concern. i really felt it in my neon. but the disengaging clutch really helped.you are going to kill me for this but my prius has electric ac. yup and electric power steering. pretty neat so that neither one affects the cars power ( or some would say lack thereof) ;)
fred from nashville probably waiting forever at this rate
Not entirely true, because you still need to generate the electricity to run the compressor. Now you also have inefficiencies in the alternator and ac compressor when converting to or from electricity and kinetic energy (something spinning). This means that having an electric compressor will actually use more energy than having it run by a pully unless the actual pully causes a loss in energy more than the conversions, but I doubt that would be true.

The only benefit would be that you could turn off the alternator during times where the power is needed, but in the long haul you will use more gas, but not much more.
 

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hmm interesting. however , dont forget that the prius has 2 electric motors and is the only hybrid that can generate electricity while using some. i know very weird. i also dont have an alternator . so believe it or not i can sit at work with my engine not on and cool the car at the same time. (engine does kick on and off as needed) its definitely not pulling any power.therre is no drag feeling like you have with standard ac and the mileage is not affected 1 iota... great car but not a sportscar. and i love sportscars. this will be my FUN car, :) if it ever arrives. i do rember i waited 4 months for my prius which was before the big gas price surge. i guess i always be waiting
fred from nashville ;)
 

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SolsticeDesire said:
Not entirely true, because you still need to generate the electricity to run the compressor.
But I think the alternator runs constantly in most cars anyway, but since it just charges the battery in most cars, much of the excess energy is wasted. Making use of the electrical energy already produced wouldn't cost any extra gas. Not sure of all the details though ... maybe I'm missing something.

EDIT: Actually, after reading the last post again about the damned thing not having an alternator anyway, the whole comparison would seem to get pretty messy.
 

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mrfredsporty said:
the mileage is not affected 1 iota
This is impossible. It would violate the laws of physics. You never get something for nothing. If you would have an infinite source of energy and the world would not have to worry any more. Maybe it wouldn't effect it much, but it would. Just thw fact that the engine has to turn on while the car is off and the AC is on means that it does effect the mileage to some degree.
 

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SlySol said:
But I think the alternator runs constantly in most cars anyway, but since it just charges the battery in most cars, much of the excess energy is wasted. Making use of the electrical energy already produced wouldn't cost any extra gas. Not sure of all the details though ... maybe I'm missing something.

EDIT: Actually, after reading the last post again about the damned thing not having an alternator anyway, the whole comparison would seem to get pretty messy.
Just because a car doesn't have an alternator per say it doesn't mean that the motors in the cars aren't used as an alternator. I believe that the amount of power that an alternator generates can vary. I know that in my Saturn when I turn on the headlights the engine revs a little higher. To me this would mean that the car is demanding more electricity, so the alternator must supply it and therefore the engine must work harder.
 

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this is fun solstice desire and your points are well taken.i dont even have a serpent belt for my ac thru the engine. dont have a powersteering belt. the engine does use split management so that even if both electric motors are being used the engine is partly recharging the 50k battery, so im sure you are technically correct that you cant get something for nothing. the observed difference is nothing. also dont forget that this particular car works by "fm". dont forget no shifting of gears. no reverse gear etc, etc.but anyway my friend i do look forward to my solstice which will arrive before im 85 (im now 61). thank you for your very spirited responses.
fred from nashville :)
 

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SolsticeDesire said:
Just because a car doesn't have an alternator per say it doesn't mean that the motors in the cars aren't used as an alternator. I believe that the amount of power that an alternator generates can vary. I know that in my Saturn when I turn on the headlights the engine revs a little higher. To me this would mean that the car is demanding more electricity, so the alternator must supply it and therefore the engine must work harder.
Yes, and it also has an affect on gas mileage.
 

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SlySol said:
But I think the alternator runs constantly in most cars anyway, but since it just charges the battery in most cars, much of the excess energy is wasted.

Uhhh...no. The alternator supplies the electrical needs of the car. Keeping the battery at full charge is a secondary function.
 

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Discussion Starter #12
So other than SkyCaptain, does anyone have a clue to my question? Maybe it's one of those hidden secrets the auto industry doesn't want anyone talking about? :)
 

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Bonzo said:
So other than SkyCaptain, does anyone have a clue to my question? Maybe it's one of those hidden secrets the auto industry doesn't want anyone talking about? :)
Maximum, 5hp. Concerning running with the top down and AC on, you would probably burn a little more gas than with the top down/no AC, but mainly because you would have it cranked up higher than you would with the top up.
 

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Primus said:
I don't notice any difference in power when driving my Sol with the air on or off.
There you go an answer.
 

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SolsticeDesire said:
Just because a car doesn't have an alternator per say it doesn't mean that the motors in the cars aren't used as an alternator. I believe that the amount of power that an alternator generates can vary. I know that in my Saturn when I turn on the headlights the engine revs a little higher. To me this would mean that the car is demanding more electricity, so the alternator must supply it and therefore the engine must work harder.
at normal idle the pullys are not spinning fast enough for the alternator to produce full power. so what is happening in your car is that the engine computer, upon sencing that there is a need to produce more electricity, steps up the engine idle speed to accomidate the needs of the car.
 
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