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: |
Can also read the thread below in my sig about the E-fan and clutch fan.
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I am against the e-fan draw HP mentality; and what I am trying to prove is that it doesn't draw any power (well maybe 0.25hp). Notice that I am not claiming that the efan gives more HP; just that itd not how some want to put it... In the e-fan link in my sig, click on the link about the S4 Fan Estimation, that gives you good info about the clutch fan. Actually 90A at 12V is only 1080 watts, or about 1.3HP. Also, the clutch fan does not take anything over 5hp. It would take less then 2 most of the time but usually in the decimal range. |
I thought the E-Fan conversion was to make more room in the engine bay... :confused:
Thats why I would eventually like to do it... :pat: |
What are you making room for? Most of the people who say they swapped to e-fan "to make more room" don't actually use any of the space they've freed up.
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Your right but its easier to work on the engine without that large shround in the way.
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Originally Posted by RotaMan99
(Post 7004361)
Your right but its easier to work on the engine without that large shround in the way.
I dont have an overly modded car but like any other 7 it needs to be worked on regularly... Its nice to clear as much crap out of the way as possible... Plus it just looks nicer... :D |
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. 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. |
Are there over drive pulleys one could install?
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So in conclusion an e-fan amp draw is next to nothing or in the decimal range 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. Are there over drive pulleys one could install? |
Originally Posted by RotaMan99
(Post 7004645)
I have never seen any but im sure you could get some made. Doing this though could over spin the alternator or water pump, depending on what you "overdrive". Personally, I would like to overdrive the alternator slightly, havn't done the math to figure out how much I could go but at idle, it seems to spin to slow to charge much.
an Overdrive pulley would be smaller than the shaft pulley(?), but i'd imagine it would only need a few mm to a cm in difference to get the desired affect. What i'm curious about though is why anyone would want HP at idle? since both the efan and clutch fan usually only spin at low speeds or at idle. There's rumors of better throttle response from an efan and most who have done the conversion agree. Besides that and space it makes no real difference in the amount of usable HP. As for my reasons for conversion the fan and shroud were broken and I'm also planning on doing a N/A->turbo conversion (so with that space I can run intercooler piping). |
an Overdrive pulley would be smaller than the shaft pulley(?), but i'd imagine it would only need a few mm to a cm in difference to get the desired affect What i'm curious about though is why anyone would want HP at idle? since both the efan and clutch fan usually only spin at low speeds or at idle. There's rumors of better throttle response from an efan and most who have done the conversion agree. Besides that and space it makes no real difference in the amount of usable HP. As for my reasons for conversion the fan and shroud were broken and I'm also planning on doing a N/A->turbo conversion (so with that space I can run intercooler piping). I can't remember if switching to an e-fan increased my throttle responce or not while the fan was off or on. Its been about 5 years. I can see how it would, but I don't think its anything to jump up and down over either. |
Originally Posted by RotaMan99
(Post 7004861)
Right, if you notice the alt pulley is already smaller then the main pully but in some situations doesn't seem small enough. They are that size for a reason though, If you do a lot of high rpm racing around then I would stay away from overdriving the alt even more.
Its not getting HP at idle, its trying to free up and HP through the poewr band that the clutch fan is said to consume. As I state before, its usually in the decimal range but can take as much as 2+ hp. I can't remember if switching to an e-fan increased my throttle responce or not while the fan was off or on. Its been about 5 years. I can see how it would, but I don't think its anything to jump up and down over either. |
The conversation is past this, but I'll add these two sentences anyway:
Those don't tell the whole story, but they're interesting to keep in mind! |
Originally Posted by RotaMan99
(Post 7004361)
Your right but its easier to work on the engine without that large shround in the way.
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Originally Posted by C.A.R
(Post 7004395)
Plus it just looks nicer... :D
I guess on the other hand... Since I have removed the stock intake, the shroud does work great as a place to set tools while I work on it... |
would you gain any throttle response by getting an e-fan?
the only reason i'd get an e-fan is cause i would like to install a reverse vented hood, which WOULD help reduce engine bay temps. |
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. Yes, as load to the engine increases. Listen, I work at Advance Auto and test a lot of alternators. When you put a load on an alternator, it puts an electrical resistance on the shaft, and makes it harder to spin. If this wasn't true - then an alternator would produce max output at idle or at WOT - which is also a known fact that it doesnt. The alternator does not increase amps based on RPM solely. Any Mechanic will verify what I have said to be true. I am a mechanic myself. Maybe you should research your stuff before you make ignorant claims... -Chris |
Originally Posted by slow7NC
(Post 7006697)
Listen, I work at Advance Auto and test a lot of alternators. When you put a load on an alternator, it puts an electrical resistance on the shaft, and makes it harder to spin. If this wasn't true - then an alternator would produce max output at idle or at WOT - which is also a known fact that it doesnt.
The alternator does not increase amps based on RPM solely. Any Mechanic will verify what I have said to be true. I am a mechanic myself. Maybe you should research your stuff before you make ignorant claims... -Chris Ohhh lord, a mechanic working at AAP :wallbash: How about kicking my 90 amp sound sytem at full blast while the car is at idle; will the alt put out its "100" amps? Yeah, didn't think so :sadwavey: :rlaugh: So in conclusion, an alt will not put its max amp output at idle, irrelevant of load... |
There is something you can do with an EFan that you can't do with a clutch fan. Switch it OFF before a run on the drag strip. That and controlling the exact on and off temps, and having it kick on and run after the car is shut down too cool things off.
But I would gladly go back to the clutch fan any day if I could. On my current setup it would spin backwards. |
Originally Posted by KNONFS
(Post 7007341)
Ohhh lord, a mechanic working at AAP :wallbash:
How about kicking my 90 amp sound sytem at full blast while the car is at idle; will the alt put out its "100" amps? Yeah, didn't think so :sadwavey: :rlaugh: So in conclusion, an alt will not put its max amp output at idle, irrelevant of load... |
Originally Posted by Low Impedance
(Post 7007417)
oh hey look! a battery! it can STORE and RELEASE electrical energy? no shit!
On any case, where is that energy coming from? And if the demand is MUCH HIGHER than the supply? |
Originally Posted by KNONFS
(Post 7009515)
We are not talking about batteries :dunno:
On any case, where is that energy coming from? And if the demand is MUCH HIGHER than the supply? Under such conditions, where the alternator is not supplying sufficient amps for the electrical draw on the system, the battery "chips in" from it's stored energy. Two problems follow from this - one is, that cannot go on indefinitely, as the battery will eventually run flat and voltage/amps supplied to electrical system will drop below that needed to keep the car running - although in practical terms, that would take a lot of time idling - possibly hours, depending on how much the battery has to "make up". Secondly, if extra load on the electrical system from an e-fan, for example, causes the car to draw on the battery while idling or at low speeds, the alternator will work harder once engine speeds increase to recharge the battery again, meaning it is possible that the extra load of the e-fan effectively remains on the engine, via the alternator and battery, after the fan may no longer be running - effectively, a deferred load. I just read Mr. Cake's writeup on "the efan myth" - he's pretty much nailed it - and he effectively deals with the reasons you might want to use an efan - its just that hp gain isn't one. You'd almost certainly gain more by switching your tranny and diff lubes to a quality synthetic. |
dejavu i swear we comment on this way too much.........
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still think this is more in people's heads than anything else, because it makes such a difference visually. There's not that much "on the engine" that's blocked by the shroud. I've worked on pretty much every part of my engine at some time or another, and only needed to remove the shroud once to remove the water pump. I'm doing something in the engine bay often and if it actually got in my way on a regular basis I'd be much more interested in removing it. What regular tasks would actually be made easier? This is the reason why the electric fan is a SIDEWAYS Add-on and not an UPGRADE. I like the looks of a cleaner, less cluttered, engine bay and so do many people. You on the other hand must be an old timer :) |
Originally Posted by KNONFS
(Post 7007341)
Ohhh lord, a mechanic working at AAP :wallbash:
How about kicking my 90 amp sound sytem at full blast while the car is at idle; will the alt put out its "100" amps? Yeah, didn't think so :sadwavey: :rlaugh: So in conclusion, an alt will not put its max amp output at idle, irrelevant of load... Did I say that an alternator will put out max amps at idle? No. Let's see what i said: "The alternator does not increase amps based on RPM solely." WOW! I said "solely". When I test an alternator while it is on a car, I rev the engine to 2000 rpms so that I can put a full load on it. Then I test it at idle and it puts maybe 50-65% of a load on it - the exact percentage I do not know. By the way we are talking about batteries. A battery is part of the charging system - it is a capacitor and a power conditioner. If you say that a battery has nothing to do with it, then please please please go take an automotive class and stay away from car forums for 3 months. Well isn't that something? Once again you should research stuff before you make claims, and please read posts carefully |
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