I removed the A/C compressor and installed the GM A/C delete bracket w/ idler pulley. The LT1 compressor clutch pulley is large and heavy (rotating mass w/o the A/C on), so removing it has to free-up a few HP.

So, how many actual HP do you free-up by removing the compressor and installing the delete bracket?

Also, later on today I’m going to weigh the compressor to see how much weight I removed.

WD

 

I'm pretty sure that you don't gain any HP from removing the AC compressor - because it just "free-spins" when the AC is not on. Only when the AC is on do you loose horsepower from the compressor.

Your main advantage to doing that is that you lost a decent amount of weight. Let us know how much it weighed.....

 

I respectfully disagree. The A/C clutch pulley itself probably weighs about three to four pounds. Even when the A/C is off, it takes energy (HP) to spin-up all that mass to 6500 RPM resulting in a percentage of HP loss.

I weighed the compressor and it was 15 pounds (I thought it would be over 20). I also plan to remove the condenser from in front of the radiator which will also be a few pounds.

WD

 

The power it takes to spin a part depends only on the torque and speed. Torque for disengaged clutch is near zero. All you save is weight, both in car parts and the sweat you will lose driving!

 

In theory, it might gain you a tiny amount of RWHP due to reduction in rotational mass... Probably not even 1 HP though... There isn't even much gain from going with a light weight flywheel and that is both a larger weight reduction and the reduced weight is much farther from the center of rotation... I also suppose that an aluminum driveshaft in theory gains a little HP over the steel driveshaft, but it just isn't significant.

I'm sure you can cut 30 to 50 lbs off the car if you delete all the AC and Heat related components... Of course if you still street drive the car, I doubt it's worth the headaches...

 

Think you need to go back and review basic physics. You can't effect a body without applying force. Force is power, so it does take some power to spin your accessories. In this case I'll bet it isn't much, maybe 1/2 hp. You could figure it out if you know the mass and diameter of the pully, but I'm to lasy to do the math.

 

Here is a dyno comparison with an aluminum driveshaft, in case anyone is interested.

 

may be you should consider modify other components in order to free some HP and weight: a combination of A/C removal, AL driveshaft and other less useful stuff might give you a few extra HP and torque that together with a lighter car should improve acceleration, braking and little handling. But everything should be done according to your final goal if it is increasing HP or having a lighter car.

 

I wanted to do the same mod, but figured it wasn't worth it, besides I hate sweating, and my car is an LE3 h&c 355.

 

The condensor spins just as freely as a delete pully would when the compressor clutch is disengauged. You can tell that just by spining it with your finger. Only way I can think of it making your car any bit faster would be because of the weight you save.

 

let me know if i am wrong, hp doesn't turn anything , torque does. so if lose weight or items that need torque to move (anything on the car basicly, since you have to apply torque to move from a stand still) any reduction of weight (especially in rotating mass) will result in a increase in torque, which will increase performance off the line (standing start), more than rolling start. http://craig.backfire.ca/pages/autos/horsepower decent read but not great.
little more info geared towards this topic
http://vettenet.org/torquehp.html

 

I agree with the above posts. The gain horsepower wise is virtually nill. Maybe 1 horsepower at most. The only gain is weight reduction if that is your goal. Me, I like the cool air so it stays in my car.

 

I'm currently making over 520 HP at the flywheel, have a custom 3 1/2" aluminum diive-shaft, 4.30 gears, every chassis mod and run consistant 11.30s @ 120+ MPH and the car weighs 3300 pounds. What specific ideas do you have for me to free-up some extra HP?

Again, if you carefully examine the clutch pulley on the compressor you will find it is “very heavy” cast metal (possibly 3 to 4 pounds). Whereas, the A/C delete bracket idler pulley is only a few ounces. Therefore, it takes more energy to rotate the greater mass.

WD

 

When the engine accelerates, the mass of the rotating components, including the pullies of various sizes and weights, ABSORBS energy . That reduces the HP available at the flywheel. It may not be much, but it is a real, calculatable number.

Consider an under-drive pulley. It increases HP at the flywheel, because it slows the accessories down, and reduces the energy absorbed accelerating them. That's why you get so little gain with the LT1 U/D setup... just reduction of inertia losses, no reduction in the hydraulic pumping losses of the water pump.

Once the rotating mass reaches a steady speed, the only power loss is due to any friction related to the component, but when you accelerate a rotating mass, energy is absorbed by that mass, reducing the power at the flywheel.

 

Well said! As I go through the gears in the ¼ mile, the reduction in rotating mass should free-up a few HP. I’m already running an under-drive damper (Jeg’s) and under-drive alternator pulley.

Also, I bracket race almost every weekend and have been running 11.30s to 11.40s, depending on weather conditions. I will be closely monitoring and logging my times over the next few races (large quantity sampling) to determine if I can see a little improvement.

WD