NeoTokyo

The hp drain isnt going to be the same, that extra load isnt going to add up to the 15-20hp lost when the AC clutch is engaged.

Also depending on your charging system it may not make a difference anyways, just depends on if you have upgraded your altenator, batery, grounding system. Shoot updating your grounding system is something most people overlook when building for horsepower, but for some reason all the tuner guys do it....

Its a good mod and electric water pumps and power steering pumps have shown dyno proven gains of upwards of 15hp each, not bad impo. But you are right, you have to take into concideration the new stresses put on the electrical system.


-Eric-

GreyStang

Well, that's a different story if you're talking about replacing a "low efficiency" mechanical water pump with a "higher efficiency" electric one. Then of course the electric pump would net more horsepower, but NOT becuase it is electric but because it is a more efficient pump.

In reality if you convert your engine rotation power to electric power (alternator)and then back to rotational power (electric motor) you are more likey increasing the amount of parasitic loss because the enery has transferred itelf a couple times, instead of direct driving the A/C pump with a belt.

And besides, when the A/C is off, the compressorpulley clutch disengages & the pulley is just freewheeling, hardly any HP is lost at all

NeoTokyo

And that is why I said "When the AC clutch is engaged."

Im still not buying what you said because I have seen results in person. Im not doubting that there is a drawn but not so much to where it equals or outweights the standard component draw.

Another thing is brought to mind, so if you add an awesome stereo then you lose horsepower? It just doesnt add up correctly, can you give me some feedback actualy live numbers on this, a webpage that has the info. I will search for some webpages based on the electric drive unit.

This is turning out to be a fun topic

NeoTokyo

Ok I did some research. My results are based on using a 200amp unit and of course 12v. ENJOY!!! (A 200amp is more than enough to power 3 electric drives let alone just the 1 without flinching and needing to draw more power.)

1 Horsepower x 0.0013404825737265415549597855227882 = 1 Watt

The conversion of Volts to Watts is governed by the equation Watts = Amps x Volts

It only takes 2.15549586 hp to make that power, now the pulley itself creates drag and that takes power away in itself and the weight of the unit, but for pure power and what it takes to produce it, thats not much at all

Do the math too and tell me if you come up with something else, I am stressed for time at the moment and I could have been wrong, I will re-do it tonight when I get home.


-Eric-

For example 1.5 amps * 12 volts = 18 watts
Converting Volts to Amps at fixed wattage

Now take those as examples and do a little math for how much power this 200amp unit is going to take.

NeoTokyo

Holdon I just told you how much horsepower is made, not how much it takes to make it. I was thinking about it while working and went "Whoops!"

Anyways the calculation that is needed is this one.



Here is the site that you can work from, I am too busy at the moment to do this. http://www.elec-toolbox.com/Formulas...l/formulas.htm

Terms: E = Voltage / I = Amps /W = Watts / PF = Power Factor / Eff = Efficiency / HP = Horsepower

Colorado_Mustang

Your smoking something good.

Electric motors do produce horsepower. Gas engines produce horsepower. How much horsepower is required to turn a mechanical pump will not change based on the energy consumed (gas/electric) to turn the mechanical pump. Efficiency is where you make gains with electric, as many electric motors are much more than 50% efficient, good ones are above 90%. Gas can only dream about this type of efficiency.

Now, your problem. You are using a gas engine to produce electricity through the alternator. That alternator creates AC power fairly efficiently. It then loses some efficiency to turn that energy into DC power. Then, you are talking about driving another motor with that DC power? 'nother efficiency loss. You will still need a certain amount of horsepower (20, say) to turn that AC compressor at 2k rpm.

Here's a fun experiment. I'm sure you have an air compressor laying around. That's a 5hp motor, give or take. Probably runs somewhere around 3500 rpm. Hook the drive of that motor through a 1:1 drive to an AC compressor. Put enough tubing on the AC compressor such that it's drivinga pressurized system. Start that AC motor and see how well it works.

Your most efficient setup would be an alternator without the rectifiers to drive another AC motor that drives the other accessories. That is, the most efficient if you discount using the stock drive system.

Their are two reasons to use an electric water pump. 1) You can turn it off at full throttle for a quick run down the quarter. 2) You can leave it on after the engine is shut off to cool your engine more.

GreyStang

Well that's probably what they mean when they say an electric water pump can get you 10-15 extra horsepower.. because they can be shut off during the short period of the drag race. However you wouldn't have the same advantage in another sport like a road race car or drifting car where the water pump needs to be running all the time.

And as far as why nobody uses an electric drive to power their air conditioning compressors, I don't know if I could find a website to support my case,, but then I don't have to lol. If it were a viable option then why doesn't any auto maker use that type of setup? They must have researched it (they're always looking to improve economy and/or power!) and yet nobody I know has an electric drive A/C

NeoTokyo

There are many reasons why auto manufacturors dont use current technology.

I still dont see how power can not be saved due to this type of modification, tell me why there are electric drive units out there for the Power steering? Those seem to sell well enough to keep them on the market.

The theory that you guys are bassis your answer from is that the electrical system is maxed to its furthest point and which our stock systems are not maxed out. And no one has still said anything about "Having a good stereo makes you lose power."

The only thing that is going to prove this are actual dyno numbers because no one is changing anyone elses mind here.

You guys arent even trying to figure out the calculation that will get the answer you need, your just saying what seems logical to you, as I am at this point too now untill proof is shown.


-Eric-

NeoTokyo

At 80% DC 12V efficiency a 300hp engine can produce 14,920 amps.

IM going to call Mythbusters on this one!!!

lol

NeoTokyo

Hmm no one uses electric drives you say because it would take more power to run or not have enough impact to matter?

Here is a list of cars that I googled that use electric power steering units and in many euro cars Electric units are used from AC, water pumps and PS units.

Vauxhall Astra
Vauxhall Corsa
Renault Clio
Renault Megane
Citroen Saxo
Peugeot 307
Fiat Punto/Brava/Bravo
MGF


Now for Electric PS racks (NO pumps)

Hyundai Atoz
Mercedes Smartcar
Mazda 3
Honda Civic

Also if its such a bad idea then why did Flaming River Make an electric PS unit?

Also, the 04+ Toyota Prius uses an Electric AC compressor in order to raise fuel economy, overall power output and reduce emissions.... Hmm now why the HELL would Toyota do that if it were not a great idea?

There is your hard facts, I just dont have the math part ready. Obviously it saves power, gas and emission so why not use it on our mustang.... I knew there was something wrong with what you guys were saying

It wouldnt make sense at all unless the electrical system was maxed out already, and based on how many amps a 300hp engine can produce, I dont think we will ever run into that problem.


-Eric-