How much hp/tq loss from A/C being on?
05-04-2008, 01:23 AM
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2003 S600 ; 1999 E55 (sold)
How much hp/tq loss from A/C being on?
Guys, does anyone have an idea how much hp/tq loss there is from running the A/C?
I usually don't run it if possible because it makes the car feel so heavy...but was interested if perhaps anyone had done a dyno with it on?
I am thinking it must be substantial, 75-100 torque loss while A/C unit is on.
Maybe some electrical engineers can figure this out, I was only industrial which at least at my school got 0 respect...
)
I usually don't run it if possible because it makes the car feel so heavy...but was interested if perhaps anyone had done a dyno with it on?
I am thinking it must be substantial, 75-100 torque loss while A/C unit is on.
Maybe some electrical engineers can figure this out, I was only industrial which at least at my school got 0 respect...
)
05-04-2008, 11:16 AM
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04 S430 (sold),05 X5 4.4i, 02 325i, 87 560SL, 85 Alfa Romeo
Guys, does anyone have an idea how much hp/tq loss there is from running the A/C?
I usually don't run it if possible because it makes the car feel so heavy...but was interested if perhaps anyone had done a dyno with it on?
I am thinking it must be substantial, 75-100 torque loss while A/C unit is on.
Maybe some electrical engineers can figure this out, I was only industrial which at least at my school got 0 respect...)
I usually don't run it if possible because it makes the car feel so heavy...but was interested if perhaps anyone had done a dyno with it on?
I am thinking it must be substantial, 75-100 torque loss while A/C unit is on.
Maybe some electrical engineers can figure this out, I was only industrial which at least at my school got 0 respect...
)If you do, then there is something wrong with your compressor as they are designed to be fairly transparent and not weigh the engine down at all.
IF there is any torques lost at all it is so minimal you would not even notice..
75-100 is 25%. WOuld you pay that much for a car that looses that much torque by turning on the AC? I think not.. that info is incorrect buddy.
Unless of course if you are driving a KIA....
I'd say 2-5% would be expected.. nothing more.
I have a 430 and can't even feel my AC compressor which stays on all the time ( in cycles of course ).
05-04-2008, 12:52 PM
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An automotive air conditioner compressor uses about 5 horsepower.
http://en.wikipedia.org/wiki/Air_conditioner
If you feel it in an S600, something is wrong. Your intercooler pump may be bad (a common problem) and the slight extra load of the A/C can be raising your IAT to where the turbos will be switched off. But you're not feeling the compressor directly.
http://en.wikipedia.org/wiki/Air_conditioner
If you feel it in an S600, something is wrong. Your intercooler pump may be bad (a common problem) and the slight extra load of the A/C can be raising your IAT to where the turbos will be switched off. But you're not feeling the compressor directly.
05-04-2008, 04:00 PM
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2003 S600 ; 1999 E55 (sold)
Good info whoover...thanks for the link!
Ok I may be off base here with 75-100 figure of loss, but definitely, anyone would agree the car does not push you back into your seat as hard when you floor it, when the A/C is on...maybe 5 hp but more torque than that...there is a difference.
Ok I may be off base here with 75-100 figure of loss, but definitely, anyone would agree the car does not push you back into your seat as hard when you floor it, when the A/C is on...maybe 5 hp but more torque than that...there is a difference.
05-04-2008, 08:13 PM
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Torque in ft-lbs is hp * 5252 / RPM.
So 5 HP will take roughly 26 ft-lbs divided by your RPMs in thousands.
At 1000 RPM, the compressor will use 26 ft-lbs; at 2,000 RPM, 13; at 3,000 RPM 9 and at 6,000 RPM about 4.5 ft-lbs. Not a very noticeable drain from the 612.
So 5 HP will take roughly 26 ft-lbs divided by your RPMs in thousands.
At 1000 RPM, the compressor will use 26 ft-lbs; at 2,000 RPM, 13; at 3,000 RPM 9 and at 6,000 RPM about 4.5 ft-lbs. Not a very noticeable drain from the 612.
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