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Does air conditioning in a car have different effects on different size motors?

 
 
Reply Thu 18 Oct, 2012 04:56 am
Hi Friends,

What would help a car not burn so much gas when running the air conditioning? In other words, if the gas consumption is awful with a 307 c.i.d. engine will it "NOT" be so bad with a 350 crate motor or a restored Cadillac 500 c.i.d. engine? What are the variable specifics on whether or not an a/c compressor will take a considerable toll on a car fuel tank and mileage? I just figure it was some kind science to the whole thing.

Thank You
Steve Holmes
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Type: Question • Score: 2 • Views: 2,731 • Replies: 7
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Rockhead
 
  2  
Reply Thu 18 Oct, 2012 01:22 pm
@SteveHolmes,
the 307 was not a great motor to start with, and has been out of production for over 30 years. and was only produced as a carbureted engine.

guessing from your choices, I would imagine you are using an old a6 axial compressor. also not very efficient...

a modern a/c compressor will use 10 or 15 horsepower away when running correctly.

this should even not be noticeable on a properly functioning V8 engine...

some intrepid folks even mounted air conditioners on old volkswagens, where 15 horses really took away from the 65 it started with...
roger
 
  2  
Reply Thu 18 Oct, 2012 02:48 pm
@Rockhead,
Tell you what, though. I can seriously feel a difference in acceleration with the ac running in my little 4 cylinder Focus. I also believe it nibbles into the gas mileage on highway driving, but there are too many variables to be sure.

I recall an old experiment performed by state police in either Colorado or Oklahoma in which they determined that driving with windows open and no ac used more fuel than windows closed and ac on. Seriously, does anyone think the staties wanted new cars ordered without a/c? Any cop worth his salt could fudge the gas consumption in a way that kept the air conditioners.
Rockhead
 
  1  
Reply Thu 18 Oct, 2012 02:51 pm
@roger,
I believe that the ford folks recommend turning off the radio and any other unnecessary equipment in the focus to achieve maximum velocity in traffic.

(don't they race them in nascar?)

Shocked
edgarblythe
 
  1  
Reply Thu 18 Oct, 2012 02:56 pm
My wife's Corolla does not accelerate nearly as well with the A/C on.
0 Replies
 
roger
 
  1  
Reply Thu 18 Oct, 2012 02:59 pm
@Rockhead,
Hey, I don't even use the casette player in hot weather. Not sure it has a radio. It's an '03, you know.
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engineer
 
  1  
Reply Thu 18 Oct, 2012 03:07 pm
@SteveHolmes,
The amount of energy the AC takes is not dependent on the engine size, it is dependent on the temperature of the inside and outside air, the efficiency of the AC unit (which includes maintenance and freon charge), the size of the cabin space and how cold you want it to be (since the compressor runs more if you want it colder.) All other things equal, engine size doesn't matter, BUT overall car performance is affected. Sucking up power from a 100 hp engine is going to hurt acceleration a lot more than using the same power on a 200 hp engine (assuming equal curb weight, etc.) It is possible that forcing the smaller engine to rev higher will move it into a more inefficient operating band and hurt gas mileage more than it would in a larger engine. That said, the difference between a big engine and a giant engine wouldn't be detectable. Both engines will still be well within their optimum operating bands.
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AnthonyMartello
 
  -2  
Reply Tue 30 Oct, 2012 10:24 pm
@SteveHolmes,
Hello Community Members,

Having an understanding of the function of an alternator and the effect on the vehicle in the event of a failure is highly important. The multitude of vehicles stranded every day on the highway due to this problem proves a serious lack of understanding the consequences of this type of failure. In most of the cases, the operator tries to jump start the vehicle with another power source only to find that either the engine will not respond or if it does it will only run for a few minutes before failing again. Alternators come in many different amperage ratings as well as manufacturers. It is important to know what type as posted on the alternator that is in place. Different manufactures have different connectors and usually will not adapt to a different system. It is also vitally important to get the right amperage for the vehicle since the amperage determines how much of a load the alternator will handle and still maintain a charge. This is related to the amount of accessories that are present in the vehicle. If the amperage of the alternator is not known, mention to the parts supplier the number of accessories such as power windows, seats, air conditioning, door locks and so on and he can determine the choice.

Best Regards,
Anthony Martello
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