Gain power by converting to an e-fan?
Is there any truth in this? It seems logical since you wont have the regular fan connected to the eshaft so there would be a bit less loss going on...
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but electrical power is drawn from the alternator thus creating the same resistence.
the more power being drawn form the alt, the more resistence is it has in order to spin it. so... no. |
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This is covered in the FAQ.
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Originally Posted by SirCygnus
(Post 6998845)
but electrical power is drawn from the alternator thus creating the same resistence.
the more power being drawn form the alt, the more resistence is it has in order to spin it. so... no. |
Originally Posted by KNONFS
(Post 6998942)
I don't buy that, the alternator will spin the same amount of RPM, will have the same resistance and will put out the same amount of amps wether you are running an efan or not.
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Originally Posted by CyberPitz
(Post 6998948)
Read that link I posted, it will give you all information you need to buy it ;)
As I said, nothing asides from pullies will affect the alternator RPMs, amps output, or resistance. |
Originally Posted by Mindspin311
(Post 6998820)
Is there any truth in this? It seems logical since you wont have the regular fan connected to the eshaft so there would be a bit less loss going on...
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Originally Posted by KNONFS
(Post 6998942)
I don't buy that, the alternator will spin the same amount of RPM, will have the same resistance and will put out the same amount of amps wether you are running an efan or not.
The problem of an e-fan using engine energy less efficiently than the stock, working clutch fan is compounded by the fact when cooling needs are high - eg, idling in traffic - , the alternator on these cars barely keeps up with demand just to run the engine electrical system, lights, and so on. Ever noticed how just hitting the brakes when idling hot causes the revs to sag, then return to a slightly higher point? That's because just the load of the brake lights on the alternator slows the engine significantly - proof that load on the alternator makes the engine work harder. The surge that follows the sag is an idle compensator, just like for the A/C, that Mazda designed in, recognizing that at electrical loads at idle tax the alternator/charging system. An e-fan is going to tax the charging system further precisely when it is least able to compensate - low engine/vehicle speeds. |
Originally Posted by KNONFS
(Post 6998942)
I don't buy that, the alternator will spin the same amount of RPM, will have the same resistance and will put out the same amount of amps wether you are running an efan or not.
The alternator only supplies the amount of current that the car is drawing...That is, a 70A alternator does not always "push" 70A out into the electrical system. If the electrical draw from the car is only 50A, then only 50A will be produced from the alternator. This is why cars with flakey (or missing) BAC valves have idle dropping issues under heavy electrical load. Switching in a high current item like the headlights, defroster grid or e-fan causes the idle to fall as the load on the engine increases. |
Originally Posted by Aaron Cake
(Post 6999035)
The alternator is not a free energy device. If you draw more current from it, then the shaft becomes harder to spin, and the engine must work harder to spin it..
If i was to follow your theory, a stock FC with a 90amp sound system, e fan, AC & headlights on; will barely move...
Originally Posted by Aaron Cake
(Post 6999035)
The alternator only supplies the amount of current that the car is drawing...That is, a 70A alternator does not always "push" 70A out into the electrical system. If the electrical draw from the car is only 50A, then only 50A will be produced from the alternator.
Originally Posted by Aaron Cake
(Post 6999035)
This is why cars with flakey (or missing) BAC valves have idle dropping issues under heavy electrical load. Switching in a high current item like the headlights, defroster grid or e-fan causes the idle to fall as the load on the engine increases.
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Originally Posted by KNONFS
(Post 6999081)
Harder to a certain point, right?
If i was to follow your theory, a stock FC with a 90amp sound system, e fan, AC & headlights on; will barely move... I am not going to lie, since i don't know if thats true or not; however I know that has RPM increases, so do the alternators amp output. |
Originally Posted by Aaron Cake
(Post 6999113)
Actually 90A at 12V is only 1080 watts, or about 1.3HP.
So in conclusion an e-fan amp draw is next to nothing or in the decimal range. If 90amps is equivalent to 1.3hp; then 45amp is equivalent to 0.75hp. So in reality an efan might cost you what, 0.35hp? A couple of things come to mind, can't think of a single person that can notice the difference between 0.35hp. The second thing that comes to mind is, the loss of HP on an efan setup cancels out with the extra weight that the eshaft is carrying with the stock fan setup, and\or any drag that it might cause on the engine. |
Yeah but if the stock fan absorbs 18hp (exageration) and the electric one which in reality draws ~15A running, then you would be gaining a decent amount. But what someone needs to do is head over to a dyno and make 3 runs, get an average, remove the stock clutch fan and make 3 more runs and take that average and that might give a good indication of how much energy it takes to drive the clutch fan, than inverse the drivetrain loss to get RWHP... anyone wanna take a guess?
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Originally Posted by Aaron Cake
(Post 6999113)
The relationship between how hard it is to turn the shaft vs. how much current is drawn from the alternator is basically linear. The shaft becomes harder to turn as you draw more current, up to the maximum current the alternator can produce. If you had a weak source of mechanical power (small engine, human) then you could draw enough power to drag the shaft down to the point where it could not be turned...Actually 90A at 12V is only 1080 watts, or about 1.3 HP. Most humans could provide this much energy for at least a few minutes....
Damnit i never thought of it like that!! Thats pretty cool. |
would it be worth it to take out my a/c pump during the summer is it worth the power or not?
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Originally Posted by RX7 7777
(Post 6999291)
would it be worth it to take out my a/c pump during the summer is it worth the power or not?
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is it worth taking out my A/C pump for more power or would i just rost in my car?
Thanks |
thanks for the info
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I wouldn't take it out if it works. It's not enough to give you enough HP, if it's just sitting there....that's like taking out the carpet in your hatch and expecting a 10 hp gain :p
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Originally Posted by KNONFS
(Post 6999191)
THANK YOU!
So in conclusion an e-fan amp draw is next to nothing or in the decimal range. If 90amps is equivalent to 1.3hp; then 45amp is equivalent to 0.75hp. 0.35hp. The second thing that comes to mind is, the loss of HP on an efan setup cancels out with the extra weight that the eshaft is carrying with the stock fan setup, and\or any drag that it might cause on the engine. |
rx7racerca knows whats up
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Originally Posted by Aaron Cake
(Post 6999597)
Basically, yes. But neither does the mechanical fan. That's sort of the point I try to make in the writeup. If the mechanical fan really did draw several HP, several HP worth of electrical power must be drawn from the alternator to do the same physical work (ignoring differences in fan blade efficiency based on different designs). So in truth neither one really takes that much power...
Originally Posted by Aaron Cake
(Post 6999597)
The clutch fan freewheels when it's not needed, so there is no serious drag on the e-shaft.
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the reason i opted for the electric fan was the room that it made in the engine bay.
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I did my e-fan setup coz all tha mad powah comes fRUM da fanz yo.
I SWEAR I'VE SEEN A THREAD LIKE THIS SOMEHERE BEFORE??? :dunno: |
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