Quick quesiton (sort of on topic) Will making a shroud for the electric fan that diverts the air to the side and out the wheel well or another area be beneficial than it being spread around the engine bay? Would this help keep temperatures down or would it not be that noticable?

 

WOW, just wow....

Dude, a mechanic is not the same as an electromechanic; so PLEASE stop trying to impress us with your mechanic degree and your AAP job...

Then let's see what I daid before you chime in with your VAST knowledge:

So you are trying to prove a point to something that I already stated BEFORE you walked in?

Should I say thank you or smack you


Full load at 2000 rpms?

I thought we already concluded that LOAD was applied through electrical draw, and NOT by rpms?!?

NEVER said batteries are not part of a car electrical system; just that WE are not taking them into consideration for this debate.

Well isn't that something, maybe you haven't read our own rules on this forum.

 

The battery is just as important as the alternator. It's clear from your posts in this thread that your electrical knowledge is very weak, yet you continue to argue with people who obviously know much more about it than you do. Your snide comments and multiple emoticons are just making you look a bit silly. Please just stop posting. Read and learn instead. And don't get all pissy about it either...

I totally agree, and I've said that countless times.

If you just did it for looks then say so. I've never said it didn't look better. That's not what I was talking about, so what's your point?

 

We are talking about the load on the alternator, and how it becomes HARDER to spin while the amps demand gets higher. At least thats what Aaron and myself where discussing; so in that aspect, we don't need to involve the battery. Sorry if you, or want be electro mechanics don't agree...

On any case, I truely belive that the efan robs power myth has been busted; like it or not.

 

I must have miss understood you then. I didn't like working around the shround and I like that fact that I don't ever have to at any point in time. One less agravating item to remove when trying to do something that requires removing the shroud.

He was refering to an electrical load. When he revs the engine to 2000 rpm, the alternator is spinning fast enough to put out its full potential and possibly more since 70amp alts don't stop at 70amps, they may go over a bit more by 5-20amps. Same goes for all alternators.

You quoted 2 sentences that mean something completly different. You quoted your self saying as the rpm increase so does the amp out put, which is not completly true. As the rpm increases from idle to around 1500, the alternator has a higher output potential. 1500 +/- 200rpm and beyond will only yeild the same output potential.

 

I understand that, and I mentioned it before; however either my english is not as good as I thought or he is incorrect. Reving the engine does not increases the eletrical load on the alt; yes I agree, it will generate more amps, but that is not the same as an electrical load.

 

He knows this. He also knows the alternator doesn't put out its full potential at idle which is why he revs it to 2000rpm to make sure it puts out its full potential. He never said that sping the alt faster would be a larger load on it, and infact it actually indirectly could. say you have a 70 amp alt, at idle we will say it puts out about 60% of its potential which means it has a potential output of 42amps. If you are putting a load of 60amps on this alt, its no longer going to keep the battery charged, adn the battery will have to foot in the bill to keep up with demand, you spin the alt faster, this will yeild more potential output and increase the spinning resistance as well since it now can and has to produce 60amps.

He is saying here that the alternator output is not ONLY based on RPM.

Here he meant exactly what he typed. Spins the engine (notice he didn't say alternator) to 2000 rpm and then put a load (Electrical load) on the alt because the alternator has a higher amp output potential.

 

There are a couple of problems with this idea...

First, there isn't a lot of room to make a duct that could properly transition the airflow through a 90° bend and out the side.
Next, even if you could duct it efficiently, the exit through the wheelwell would have to be fairly large which would significantly weaken the car's structure.

Assume though that you managed to overcome the above issues- now where does the rest of the engine bay get air?
Without the airflow through the rad you've got the engine/manifold heat to deal with...ignore that and your temps would skyrocket, especially on a turbo car.

Much better I think to figure out a properly vented hood...

 

I guess I misinterpreted what he wrote; I thought he was saying that by reving the alt to 2000rpms, he was "loading" it.

 

It happends

 

Gain power no.. your car will still have the same hp and same tq before and after HOWEVER there is a possibility of acheving more usable hp/tq.. but I highly doubt it.. in theroy I think the change from clutch fan to electical is a sideways move I dont think u will loose or gain anything except more space

Dave

 

If by "robs", you mean uses a lot of power, I think you made this myth up yourself. I don't remember anyone claiming that. But power generated by the engine is used to run an e-fan, and the same amount of work must be done by the engine to move the required amount of air no matter what fan is used. Most seem to miss that basic point.

I only every commented on the supposed easier access (you still haven't answered my question on that). When quoting me you've changing from easier access to better looks and back again...

 

There seems to be a misconception on what an efan do; some believe that you will gain HP, and some believe that you will loss HP.

What I've been trying to prove is that none of those are true; granted, by switching to an efan there will be a less than .25 hp loss due to electrical load, then again, by removing the OEM fan you are eliminating 1.5 lbs from the e-shaft, plus whatever drag is created when the cluctch is engaged.

 

Welcome to my posts from five years ago...

The fan is not supported by the e-shaft, it's supported by the water pump.

But you're not eliminating this load, because like I said, the same amount of work still has to be done by the engine whether you have a mechanical fan or an electric one. You're simply moving the "drag" to the alternator, which is even driven by the same belt.

 

No not at all. Its both. You think because I post something different in 2 different posts, that means I changed my mind? No, how about letting you know why I also did it.

Are you talking about no matter what electric fan is used or compairing the clutch to an e-fan? The E-fan will take less power from the engine then the clutch. Even a 18 amp flexalite fan rated to move 3300 CFM at zero static pressure will only take an estimated . 45hp with 20% inefficency for both the fan and alternator.

The clutch fan, at 2900 CFM at zero static pressure takes an estimated .90hp. Now
at peak efficiency the clutch fan would be taking over 2hp while trying to pull a little over 2500 CFM. An electric fan will never take this much.

Correct me if im wrong but I don't see how what your saying is true.

 

I think you're overestimating the efficiency of the alternator and fan. 50% is probably close for most automotive stuff.

Still, if we assume that both fan blade designs are equally as efficient, it takes the same amount of energy to move the same amount of air...Mechanically there is no double conversion loss as their is electrically.

This has been an ongoing debate for years, which is one of the reasons that I made my e-fan myth page....which of course contains all the information mentioned in this thread already.

 

SO what is a good alternator replacement for the FC 70 amp to remedy the E-fan electric draw issue while running a stereo, amps, subwoofers, with an Optima yellow top battery? FD? Same setup? mods? Aftermarket alternator? Would I need an upgrade to my alternator then with the Optima yellow top?

 

FD alternator is also a direct bolt on.

 

I was under the impression one had to alter the attaching harness, is this inaccurate?

 

I, as well, thought there had to be something else to do when swapping to the FD altenator other than just remove/add.

 

Confirmation? Perhaps inaccurate as well--Verification please.

 

I thought you were a precusor of just one of them.

That is true, don't know what I was thinking

Agree, except that I had a brain fart and thought that besides the drag of the oem fan, there was also the "weight issue" on the e shaft. I was obviously wrong, and that only leaves what your wrote; which means that there is absolutely no difference between one and the other (in terms of HP).

 

Only if you have a S4, for the S5 is a DIRECT bolt on swap; this is assuming that you have converted the FD alt pullie to a V one.

 

So for an S4, there needs to be a V pulley? What is that? What kind of modifications are needed for an FD to work on an S4 please. Thanks!!!

 

You saying the alternator and fan motor are only 50% efficient?