Robinhood150

BTW, I welcome any and all critiques of my analysis, I am by no means an automotive expert. However, this is an interesting subject and I think I'll post it on an automotive engineering forum and see what everybody there thinks about electrice Vs mechanical. I'll get back to you guys.

rimpainter.com

Steve, don't forget to mention that the fan pulley extension has a significant weight (maybe 1lb?) and rotates under all conditions. By going electric, this piece is eliminated. Interesting stuff BTW.

Robinhood150

Well, I didn't include that because the rotating mass doesn't really waste energy, it stores it like a fly wheel. The engine uses energy to spin up the pulley but then that kinetic energy is transfered back into the engine when you let off the gas pedal.

There are really 2 discussion here, one is efficiency (mileage) and the other is perceived "power" gains. Spinning up the rotating mass falls under the perceived power gains category.

Hmm...on second thought, perhaps that energy IS wasted when the spinning pulley transfers energy to the crankshaft, then to the pistons and then to the air via compression braking (because the gas pedal isn't being pushed), then out the tail pipe in the form of hotter air. Boy, this is fun...much better than working for a semiconductor company, hehe.

rimpainter.com

Hey watch it!

You too?

grams72

Simple Moorhead here: Simple Moorhead theory to follow

The mechanical fan gets its power from the Crankshaft as does the powersteering pump, the a/c, the H2O pump.

If you remove the heavy metal fan your freeing up power from the engine, but the alternator is still getting its power from the engine.
How much drag is put on the alternator if you load up your electrical system?

Its not totally the weight that your removing, its also the drag on the crankshaft.

Most drag racers remove the Power Steering pump and the A/C.
Move the Belt driven Fan and sometimes the water pump to electric. All in an effort to free up power for the rear wheels.

Your correct that there are two issues here but in the case but they are very close in relation.

Robinhood150

Right now we don't know how much drag is put on the engine via the alternator in terms of torque, although there is an equation to figure it out (but I'm not going to look it up because I'm lazy). But, like I said above, 1200w=1.6HP. The 3.0 has 150 HP at it's peak so that's 1% of it's total power. So, 1200w via the alternator, the power loss is 1%. Keep in mind that as you move up and down the power curve that % changes because you're not producing 150HP at idle.

Like I said before, removing mass will allow the engine to spin up faster producing more kick in the pants which is what drag racers need to get that extra 1/10 of a second. So does removing mass translate into more power? I'm going to say yes and no. In the short term (the 10 seconds it takes for a SUV to get up to 60mph) I'd say it could, but I question how much of a difference it will make. I mean really, is that 5HP, if that, going to mean the difference between getting ahead of the Chevy Tahoe in the next lane? In the long term, no, because the alternator has to work over a period of time to replenish the battery. Drag racers are only interested in the short term.

Robinhood150

Yup. Stuck behind a SEM all day.

grams72

I understand what your trying to say but I dont agree.

Its all about gaining HP where ever you can, a couple here and a couple there. The bonus is if they are gains that dont cost that much per horse.

5hp will not make a differance but it you do many mods they will all add up,
1 MPG gain is not a big deal but 5 mods that each add up.

grams72

Check this link out:

http://www.fordmuscle.com/archives/2...an/index.shtml

Robinhood150

Well, now are we talking about the 3.0 or just engines in general? Because nothing one does to the 3.0 is going to matter much and to get any real gains one might as well swap in a 3.4, heheh. But if you're talking just engines in general, the yeah, depending on how good the fans, air filters, etc are originally designed, things will add up. I guess this is where we'll have to disagree since I don't have any real numbers for the clutch fan. But, I'll see what the automotive engineers have to say and get back to you.

All I can say is that I didn't notice much when I switched to the taurus fan for my 3.0. Mileage is the same. Power is subjective so...I didn't notice much either, maybe the engine can spin up faster.

Oh, and 1mpg is a pretty good gain, that's almost 6% better.

Maddog

I will post my conclusion tonite after work.write now i have to go.

Maddog

I Have Taken on board the valid argument from RobinHood.& agree that the overall gain of a electric fan over all driving situations is minimal,but i also believe that there are greater benefits for some drivers than others ,those who spend a lot of time at highway speed will not get much out of the mod.but those who spend most of there time accelerating between lights & intersections will possibly find this mod more beneficial.

My reasoning behind this is tricky to explain but I will try.when driving around town ,zipping between lights etc,you will be sitting still for short burst's,then accelerating for a small distance then stoping again,when doing this with a stock fan you accelerating is often laboured by the fan loading up a highish amout of weight on the motor,as the motor heats up while you sit still,which stops right about the time you need to stop again.then does it again the next time you accelerate.all this means you are using more throttle over this short distance than you would otherwise need if you didnt have the fan.the problem is that this short distance adds up to almost the constant time of driving when you think about it.
With an electric fan there would not be so much laboured acceleration ,simply because the alternator will not be under to much strain at all ,because it simply has more than enough capacity to power a lightweight fan,certainly no more than using your lights or heater etc.
also the electric fan will do a better job of cooling during the times you are stoped as it will have the same spinning speed regardless of what the engine speed is(unlike stock fan which relies on engine speed.),therfore it may not be using any alternator power at time if accelration(not always though).
so the result is that you will need lees throttle to accelarate the short distance's that you constantly repeat(adding up to you main driving time.)

so in summary,if you drive around the city alot it would be beneficial to use a electric fan (but i admit it MUST be hooked up to a temp sensor).
if you spend most of your driving time coasting at highway speed rather than accelerating constantly.you will not notice any real benefit ,in fact the kenetic energy of the heavy fan may even help.

What do you reckon,it does make some sense doesnt it ???

Highland Runner

I agree with Robinhood. I put and electric fan on my old truck with a 22re in hopes of gaining power. No power or mileage increase at all. That fan took a LOT of power. The lights would dim a night when it came on. I could feel it come on when driving on a flat highway. It felt like when the AC kicks on just smaller. The wire to the fan got very hot while it was running. The fan drew a little more power than the Tarus fan and it draws a lot. The Flex a Lite designed for the Toyota like UKMeyers has draws much less power but is expensive. If I do an electric it will be that one.

Robinhood150

Well, a couple things...the amount of torque the alternator exerts on the engine is proportional to the amount of current drawn. So, the more current drawn the more load on the engine, it doesn't have to do with the capacity of the alternator. Also, did you know the stock alternator for the 3.0, at least on our US models, is only 60 amps? The high setting on the taurus fan uses 40 amps continuous. I read somewhere the low setting only draws around 15 amps.

I have no idea how much the truck uses just to operate, though. I might tend to agree with the stop and go reasoning though. But I don't have any data to back it up.

Maddog

Yeah ,for me its all about the stop & start.im trying to avoid the data stuff ,your mathmatics is far stonger than mine,to me it just seams to make some sense in my situation,but i will certainly try to find out the amps needed for the one looking at,being that it is off a diesel 4runner i think.I just think that the pros may just outweigh the cons.

motrhedx81

Just put a lower temp thermostat,and a high flow water pump and a mechanical flex-a-lite from LC Engineering. Cheap and very reliable. It does make a good bit of noise, but it keeps it real cool.

I would imagine the extra drag from the alternator is going to be much less than the mechanical fan. The alternate creates an internal force but it still an open connection working on magnetic forces.

Robinhood150

Ok, so here's what the professionals said on the automotive engineering forum:

It's still unclear as to exactly how much of a difference there is between a mechanical and an electrical, but it still sounds like they're pretty close.

Maddog

That quote explained what i was trying to say in my conclusion,(but he explained it much better,thats why he is a proffesional & im the kind of guy who thinks anything can be fixed with a FBH.)
The clutch fan is always engaged untill a certain engine rev's is obtained(usure what rev's my guess is around 2000)then it lets the fan freewheel or slip to an extent,but you are still turning the clutch itself all the time.
I have had cars with either a electric fan or no fan at all,& where i live there has hardly been a time when the fan was needed.
so for $80nz ,i think its worth a try.

potroast

when the electric fan is on, you're not gaining anything over the mechanical. HOWEVER, the idea is that the fan doesn't need to be on all the time... especially when you're cruising on the highway. So when you're going say 65mph, and your fan is off, you are saving from not running the mechanical fan... Plus, it could be argued that the fan is still spinning (due to air passing through the radiator) so it's giving back a little EMF... not much, but it's generating some voltage.... that's right, it's giving back, and not taking. :p

Robinhood150

Yeah, I thought about the 65 mph air making the fan turn, but that applies to both types of fans. The air is still helping the mechanical fan turn so there's less work for the engine to do.

Also, when the electric fan is not on there is no electrical connection to the battery so the electric fan motor isn't really giving back to the battery.

Hmmm...come to think of it, since the mechanical fan is still coupled to the engine the high speed air would give back more energy to the engine than the electrical fan, assuming the 65 mph air is turning the fan faster than the engine can turn it. I know, not likely at all, but you started it!