Rotating mass is rotating mass, if you're spinning it, it costs power, simple as that.
When a regular road car at 60 mph puts off a contrail, the humidity is pretty high, since I'm in a bay area, we get humidity levels at and above 100% frequently, clouds pop up out of nowhere, and it normally rains that night

 

taking off the A/C will maybe give you 3-5 HP. Bc taking off the A/C will lighten up the load on the flywheel, thus, giving more power to the other parts of the car that are related to the performance area.

 

Actually... no it's not that simple. This is an oversimplification of the problem. The amount of acceleration gained by the removal of fractions of pounds of rotating mass is insignifigant when compared to the mass of vehicle reduction between a full and empty fuel tank.

Relative Humidity can NEVER go above 100%. It is completely impossible. It's a ratio of how much water is in the air divided by the amount of water that it could have. Therefore you see that it is IMPOSSIBLE to actually contain more water than it has the potential to hold and subsequently, a relative humidity number above 100% makes no sense at all.

 

You must drive a powerful, heavy car. The bare a/c pulley on the compressor, without the clutch engaged weighs about 1.5-2 lbs. to a little non-vtec 4 cylinder, it makes a difference, now if you don't believe me, enjoy your heavy, powerful car and we'll both just drop it, but to the guys that drive the older, small, lightweight cars where 3-5 HP freed up makes a difference, they know what the effect is, whether it makes sense or not.
I'm not going to argue, I mean, I only live here... Have you ever heard of fog?

 

yes I've heard of fog, but that doesn't mean that relative humidity goes above 100%.

It does not take 3-5 hp to turn a 1-2 pound pulley. Without doing the actual calculations, I would imagine, under normal acceleration you're robbing about 0.1 hp.

--Go take a dump and you'll have a better performance increase.

 

I'm not trying to nit-pick, but people like you are following the wrong leads to squeeze more power out of your cars. I spend six years in school studying this stuff and have two degree to back up the stuff that I say (humidity included). I'm not bs-ing or just pulling junk out of my butt. I'm telling the truth that the little free spinning A/C pully doesn't not rob a significant amount of power to even worry about.

When you start looking at this level of "power loss", you should be considering other things first, like completely gutting your interior, getting rid of the spare tire, and only running with 1-2 gallons of fuel in your tank.

 

I believe you have some things confused. People like me have spent more time than would be recommended for a normal person's sanity around cars and testing various changes. By the time you take a 2 lb. pulley and drive it 40% faster than the crank, even with no drag, you're costing HP that can't be afforded on a small 1.5-1.6L non-vtec engine with ~6500 RPM redline for the performance minded individual. Engines with more HP don't seem to get affected nearly as much. Okay, okay, my humidity figure might be a bit exaggerated but you can still go in a tunnel dry and come out the other end with a wet car. "Significant amount" is a very, very relative term. Dyno testing has shown that as much as 3-5 HP can be gained from the deletion of the A/C pulley, 6-8 HP from the deletion of Power Steering, 2-4 HP from a lighter flywheel, and between 5 and 30 can be gained from a completely lightened and knife-edged rotating mass. The less weight the engine has to turn to stay running, the more power it can transmit to rotating the crank faster, the trade-off is less carry-through inertia, which is why street engines are not built the same as race engines, but the A/C does not help the inertia of the engine, so it is pointless to spin.
Right! Let me run around in my car that has no creature comforts, looks horrible and has to be re-filled ever couple blocks, but at least I'll have the belt on the A/C in case the mustang exhaust starts burning my face too much...

 

This is a good discussion.

I'm not discounting your statistics, however there are some very important items that you must be made aware of... First of all, it sounds like you used a wheel dyno to do your comparison testing, am I correct? These systems are inherantly flawed. They produce consistent results, but like many other pieces of equipment, are only good to an accuracy of +/- 10 to 15%. That's fine, let's asume the dyno you used was dead nuts accurate. The way these dynomometers measure power is to see how fast you can accelerate a very large heavy drum. This is a transient measurement. This uses an acceleration quanitity to calculate power out put, rather than measuring torque and computing power. This method of measuring acceleration will result in an observed power output increase when there really isn't one.

T=I*a T is torque, I is mass moment of inertia of your entire system, a is acceleration. For a wheel dynomometer to work you must assume that the I for the drum your spinning up is MUCH greater than the I for the system your measuring. Yes, I know that you do a coast down test, but that has it's problems too. Knowing T and the engine speed, power can be calculated. A much more accurate dyno that would result in NOT measuring power increase based on changing mass moment of inertia of your system (lightened flywheel, removing belts and pulley, etc) would be one that samples the power at a steady state speed. This means you would hold the throttle wide open and measure the torque by adjusting the the amount of reverse torque needed to hold the engine at a given speed.

Now... that I've said all this, I am NOT dismissing the fact that lighter wheels, flywheel, and fewer accessories will allow your vehicle to accelerate more quickly... you WILL, but you don't have any more power.

My whole point all along is that the when comparing the performance increase with the discomfort level associated with not even having the option to select using air conditioning... it's not worth it in my mind. <---That's entirely an opinion. Especially when I can maintain the option of still being able to defog my windows, which sounds like it would be an issue in your area, or keep the A/C off and know that I'm robbing only a very small fraction of the available power to turn what is essentially an idler pulley.

BTW, I'm not some displacement loving freak, I own a 1995 Integra GS-R with a JRSC mated to it... And I can proudly say that since the vehicle has been in my possession, NO ONE but me has touched it. Every install, every repair, all done in a tiny two car garage

 

You were describing how a water brake engine dyno works. However, you have to realize that water brake dynomometer's are flawed more than inertial "spinning drum" dynos, here's the reason: Water brake dynos have water pumps, impellers, etc in the system made of rubber. To maintain the utmost of accuracy, these dynos have to be torn down and rebuilt anytime the dyno sets unused for longer than 2 weeks because the rubber develops a memory and flaws the pressure readings and thus the calculations determining the power at a given RPM, water brake dynos also need to be rebuilt periodically when they're used constantly due to normal wear that comes from rubbing against the pump housings. Failure to rebuild the pumps on a periodic basis in either condition causes a peculiar result: engines always show gains over previous tests, when in fact there is no true gain.

Inertial dynos can read power via the crank, or from the wheels. The advantage of an inertial dyno isn't in accuracy, it's advantage is that it can read and measure the power output of a setup during acceleration without pausing at various RPM intervals, which takes time and causes more wear on the engine than an inertial dyno. An inertial dyno's accuracy comes from knowing the diameter and specific weight of the roller drums, which [with proper periodic cleaning] doesn't change. Combined with magnetic pickups and a computer, an accurate pull is just a single run in second or third gear away. Now, for all intents and perposes, a chassis dyno measures how fast you can spin the rollers, that is, how much HP is making it to the wheels without being wasted in the tranny, turning the flywheel, or spinning the wheels.

Since we're discussing dynos, it should be mentioned that engine dynos will always show more HP than chassis dynos because drivetrain losses can not be accurately predicted, just as the "SAE corrected HP" for altitude differences are an educated guess at best on chassis dyno pulls.

Back to your equation, HP is torque applied over a time interval, and the way Hondas generate more HP is normally to apply that torque faster over that interval, which is acheived by reducing the inertia it is forced to accelerate if you can't make use of more fuel available in the cylinder to burn [stoichiometric ratio still needs to be observed]. So using your equation, are you still saying that if you reduce the inertia slightly and increase your acceleration more than necessary to maintain the same amount of torque you don't gain any power? Of course, there is a limit which starts to yeild diminishing returns, but your comment of "but you don't have any more power. " isn't quite right since you're effectively decreasing inertia in order to accelerate the mass faster.

BTW, my statistics were done on a new inertial chassis dyno. We had to play

 

My A/C is removed, and my defog still works btw, since defrost/defog is a heater circuit driven item.