quote:It takes about 30 hp to move an Accord sized car at 60 mph. Under those conditions one will easily get 30 mpg. If the AC were taking 5 hp, then running the AC would cause as 5/30 = 17% hit on fuel economy, or a resulting 25 mpg. Differences I have observed have been more like 0 to 1 mpg.
Originally posted by C4Dave: About 5 hp.
quote:He also has himself convinced that it takes about 1.5 hp to run the lights on a car at night. His power consumption figures are high. Car bulbs are power rated at nominal operting voltage of 14.? volts not 12 volts, so his increase of power calculations based on operating voltage added a power consumprion boost that doesn't exist. Also automotive alternators are about 60% efficient and belt drives are 95% efficient or battery. Power consumption to run a cars lights is more like 150/746 = 0.2 hp. Crank in about 55% system efficiency and it takes .36 hp, not 1.5.
Originally posted by kenw: Here's a link to a guy that at least knows how to do math. Buried way down there is a statement re: a/c of 6hp loss. But i will insist that it does depend on the compressor type and size as well, altho it may mean only a bit of difference. The old GM piston pump compressors (long and round), were great compressors but true power hogs. Modern rotaties are more efficient. http://mb-soft.com/public/headlite.html I just may use my AC in the car more often.....
quote:????? [ July 30, 2005, 12:08 AM: Message edited by: 59 Vetteman ]
Originally posted by XS650:quote:That's easy to verify. If it's taking 10 hp, then your highway gas mileage would drop from around 30 mpg to 20 mpg.
Originally posted by Virtuoso: I would imagine the A/C system on my Saturn takes at least 5, and more likely 10 HP.
quote:Old (from the 70s) figures I have seen put the cooling capacity of the average automotive AC unit at 3 to 5 tons, or 36,000 to 60,000 BTUs.
Originally posted by Jason Troxell: So you think AC takes about 1/2hp? That is about 370 Watts. Considering the 12000BTU window unit I have consumes about 1200Watts, I can't see 370Watts keeping an uninsulated glass box very cool. I'd bet the 5hp is a fairly close estimate.