i just rigged up a efan tonight, not because i wanted to but because a belt took care of my old one. jw how much hp this frees up? the fan is currently hooked up to a switch were the security button used to be so i can turn it on and off. so how much hp when shes off?

 

.75rwhp...

 

Almost nothing if anything at all. Any gain you get from getting rid of the drag on the engine is lost in the increased draw of power.

 

Loss of electricity can be countered by a more efficient alternator. Any real hp gains though with a E-fan are done only in a good setup.

The E-fan needs to be wired so not spinning at high speeds. It also needs to the right size. Not too big to be too much a draw on power, but hopefully big enough to cool the engine at idle. A better alternator will always help the power draws, but the a bad setup and you will have poor cooling or high end power draw.

 

thats why i was asking how much of a gain when the fan is switched off. now to disconnect the p/s and a/c and see what happens haha

 

The stock S5 fan freewheels unless the radiator is hot.
So no measureable power difference.

But, if the stock fan clutch is worn out it's:
Less expensive. (Escourt or Tarus fan from a junkyard)
More room up front.
If the air pump is removed, the single alternator belt will drive the water pump.

 

the efan i put in is off a tarus, and it pushes a good amount of air. when its on it keeps the car a tad cooler then with the stock fan.

 

Actually, a new stock fan will out pull any electric fan.
But - I'm assuming your fan clutch was well worn when you pulled it.

 

yea, it was. the belt just kinda finished it off. i didnt really wanna go with a efan but i have to say i like the extra space

 

 

Electrical components ALWAYS use more power than their mechanical counterparts (in this case, fans), due to the inefficiencies of the electric motor itself, which is dissipated as heat (it's the main reason motors get hot, including our alternators). The only scenario where an e-fan makes sense is if you can run at least 50% of the time with it off (highway cruising). Otherwise, you're better off sticking with the stock fan setup (make sure the fan clutch is good, of course)...

Running an e-fan most of the time wastes far more engine power than the stock fan ever will...

Pyrojunkie- there is no such thing as an efficient alternator- it's a design that's just as wasteful as an electric motor, but it's the best us silly humans have come up with so far (room temp superconducting wiring coils & magnets might happen one of these days, that would be cool )

If you install a bigger alternator, it just takes that much more engine power to turn the bigger rotor coil assy through the stator fields, you don't get something for nothing... Let's say the base 55A alternator needs 10 horsepower from the engine to do its job (just pulling these numbers out of my a$$ here, but I would bet it's close to that, if not more)...Throw a 90A alt on there, and you're going to suck the same horsepower if you're pushing 55A with it...Kick it up to the 90A rating, and you're going to use up something close to 18 horsies from the engine. Laws of thermodynamics, too bad we can't beat 'em

 

does anyone have a link to a write up on how to properly install a black magic fan?

 

Flex-a-lite makes a strong fan - BUT, the thermostat they use has failed me and others.

 

is a 11.3 amp draw to much its a 3025 cfm, or should i get at 7.8 amp draw at 2385,i have a fd alternator, the reason im upgrading my e-fan is cause a fmic was installed, and for those of you looking for a fan at a kick *** price and some freeze 12 for your a/c at a kick *** price check out this site

http://www.sherco-auto.com/

 

Go with the most pull you can get.
I'm saving that link for sure.
Thanks..

 

Hm. So if I do mostly highway driving, I could switch to an efan & leave it off while running at speed? I wonder if it would affect power draw enough to be noticeable in fuel economy.

I'd probably use a temperature switch though, because otherwise I'd forget to turn it on coming off highway runs, and cook something.

-=Russ=-

 

were would i get a temp switch?

thanx

 

Whoa! Hold on a second there...

Properly built electric motors approach 98% efficiency. It is only the cheap, consumer grade and automotive grade motors that are crappy. Many of them don't even have real bearings (most e-fans I've seen have simple bronze bushings), have poorly designed and constructed comms, etc. GOOD, PROPERLY BUILT (ADC, Siemens, GE, etc.) motors are very efficient. WAY more efficient then you could ever hope to get a gas engine (the best are around 30% or so).


PS. Only Joe Newman can beat the law of thermodynamics...LOL.

Edit...Also, http://www.aaroncake.net/rx-7/efanmyth.htm and http://www.aaroncake.net/rx-7/efaninstall.htm

 

What do you need to know? The Black Magic is the easiest one to instalL!

 

yea i know it's easy i just want to have a guide for the wiring

 

deleted.

 

"Properly built electric motors approach 98% efficiency. It is only the cheap, consumer grade and automotive grade motors that are crappy"

Yes, Aaron, you're correct. In fact, I've read of damn near "perpetual motion" motors approaching 100% efficiency in the lab (but it's very cold in there, lol...)

I'm not talking about special purpose motors, stuff in the lab, etc....I'm talking about the equipment we mere mortals get to play with on our cars every day...

If you add up the power losses it takes to turn the "automotive grade" alternator, the power loss through the wiring, and the power loss to turn the "consumer grade" e-fan, I'd bet it would be something close to three times the power loss attributed to the stock fan, if not more...That's the point of my little "story", not that we "silly humans" couldn't make an something as magnificent as an efficient motor. In fact, as humans we have developed some truly inspiring creations, nuclear weapons among them, but what good do those do?

BTW-Who's Joe Newman?

 

I realise you're were just pulling numbers from your *** but it's easy to work out some real numbers.

An alternator that's rated at 70A (stock S4) is generating 14V x 70A = 980W of electricity. Assuming an average efficiency of 50% (I believe it varies quite a lot with temp and voltage) and you're drawing 1960W or 2.6hp from the engine.

Using the same numbers but increasing the output to 100A (FD alternator upgrade) means about 1.1hp more engine power is used.

These numbers are pretty small on an engine making at least 150hp. You can see why I'm highly skeptical of huge power claims from under-driven pulleys. Slowing your S4 alternator down 20% will save you a whole 0.5hp...

An electric fan that draws 15A while running (not unusual) will only be drawing about 0.75hp from the engine. But before anyone says "I told you electric fans need less power than mechanical ones", you need to do the same amount of work to provide a certain amount of cooling, whether you use a mechanical or electric fan. The inherent losses in converting mechanical power to electrical power and back again means the mechanical fan actually uses less power to achieve the same result.

 

Depends on your electric fan... I got one that pulls over 16,000 CFM

 

16000 cfm? wtf, were did you get that?