Hp Losses From Ac Belt?

z85violator · March 29, 2008

just thinking about taking my ac belt off for a couple days to see if my 2000 5.3 will run a bit stronger?

anybody try something so simple? shouldn't cause any harm to anything right.

vranasaurus · March 29, 2008

just thinking about taking my ac belt off for a couple days to see if my 2000 5.3 will run a bit stronger?
anybody try something so simple? shouldn't cause any harm to anything right.

How much HP do you actually think is lost from the A/C belt? My guess is it is less than 1/10th of a HP. Hardly enough to make any noticeable difference.

When the A/C is not on the clutch on the compressor is disengaged and it is free spinning.

I wouldn't waste your time.

z85violator · March 29, 2008

makes sense. thx

when the dash knob is on defrost is the ac working?

Rado10VicRed · March 29, 2008

it def makes a difference if your racing for time, it could be the differece in .1 or .2 of a second and that matters when racing. my friend and I race a SS and we take it off when we race.

Starrman · March 29, 2008

no it doesn't. Like stated above when the compressor is off the clutch is disengaged and the pulley freewheels. Take it from someone whos been racing cars at racetracks for the past 20 years and have tested with/without belt.

Now if it runs other accessories, like a serpentine belt.... power steering and water pump, yeah. They make "underdrive pulleys" to help free up some hp caused by parasitic loss from accessesories. They usually consist of a smaller crank pulley, larger water pump pulley, and alternator pulley.

Rado10VicRed · March 29, 2008

well with an LS1 engine, the a/c belt comes from the main drive pulley which adds more stress to the alternator which takes power away from the engine, its common physics. i can show you dyno graphs if you want proof.

Mikeee · March 30, 2008

makes sense. thx
when the dash knob is on defrost is the ac working?

Normally, the A/C is engaged when the defrost mode is activated. It dries the air going to the windshield.

vranasaurus · March 30, 2008

well with an LS1 engine, the a/c belt comes from the main drive pulley which adds more stress to the alternator which takes power away from the engine, its common physics. i can show you dyno graphs if you want proof.

Explain too me how the A/C belt, which has nothing to do with the alternator, adds more stress to the alternator?

The fact that the A/C belt comes from the main drive pulley doesn't effect the alternator one bit.

When the A/C clutch is disengaged it requires almost no work (force * distance) to turn. It's common physics that when the work required to rotate a shaft is near zero, as in the case of a disengaged A/C compressor, the power(work/time) lost from said turning will be near zero.

This guy is asking how to get a little more power out of his 5.3 and that is not going to happen by removing the A/C belt. Because the A/C belt is not causing him to lose any power.

Rado10VicRed · March 30, 2008

On a LS1 engine, the a/c belt sits directly behind the main drivershaft pulley belt, the a/c belt and the serpintine belt both run off of the main pulley which is powered by the crankshaft and when you take off the a/c belt that is less stress on the crankshaft which uses less power.

im sorry i was wrong when i said the alternator, my bad, but the dyno sheet doesnt lie, and another thing work for a pulley is the integral of torque(rotational inerita*angular acceleratioin) Dtheta and power is torque*angular velocity. Work equals F*d in pure translation.....nice try though vranasaurus

Starrman · March 30, 2008

uh, I think the crankshaft pulley runs the alternator...not the other way around. Also, when the a/c is off and freewheeling it is not putting any more load on the electrical system to cause the alternator to be under anymore load.

BTW, dyno pulls are never exactly the same from one pull to the next. There is always a varience of a couple hp/tq due to engine temp, air temp, fluid temp in everything like axle, tranny, motor, etc

Rado10VicRed · March 30, 2008

yea my fault about the alternator, but it still uses power you cant deny that

Mikeee · March 30, 2008

I think what has happened here is that people have different visions of the routing of the belt(s).

On my 03 5.3 it has a main s-belt that does not include routing to the A/C. There is a smaller/very short belt that is driven by the crankshaft pulley that only goes to the A/C and has its' own little tensioner.

I doubt that I could measure the difference (in power loss) between the A/C not being engaged and the belt not being installed.

I'm sure that in a "lab" condition the difference could be made, but...in the real world...nope.

My 2¢

svensk · March 30, 2008

post the dyno sheet.

the ac shuts off when you wot anyway for the very same reason of performance.

Rado10VicRed · March 30, 2008

ok thats your 5.3 but this is a LS1 and since it is connected then it does take power......they were sayin that i was wrong and i was just tryin to prove my point, but for a 5.3 since they are not connected then no i guess it doesnt matter.