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electric fan

Posted by jl1371 
June 04, 2009 03:57PM
Has anyone set up an electric fan. I have a crown vic fan and most of the wires to set it up. I was reading Peters post about engine mounts and remembered that I have this fan and would like to take the power off the motor. But am I signing up for a huge job and should just leave well enough alone.

Jack
June 04, 2009 04:22PM
First thing to do is decide where the fan will fit if at all.
Then you need to wire it in properly. The fuse/relay box already has slots for the fan relays and fuses...use these if possible. If not, there is also an auxiliary relay holder by the main box which was intended for this type of add on.
Definitely power the fan through a relay and fuse.

Next, you need to decide if you want the fan to be automatic or manually operated. Personally, I would set it up for automatic operation with a manual override.
You can get a controller thermostatic switch that mounts in on of several places.
rkj
June 04, 2009 05:12PM
But then, after all's said and done you have another electrical device to go wrong.

Keep it simple, my thoughts B)
June 04, 2009 05:40PM
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rkj
But then, after all's said and done you have another electrical device to go wrong.

Keep it simple, my thoughts B)

Exactly, so rip out all the fans. Drive so fast you don't need them, and never stop! smiling smiley

Is the engine drag that much less? After all, another device that draws power is going to increase the resistance within the alternator.
I'd bet large money a belt driven fan still has more resistance, but is it all that much when it's all said and done? Anything halfway scientific concerning this out there?
rkj
June 04, 2009 08:41PM
The less scientific the better B)
June 04, 2009 09:02PM
I'm willing to bet the electric fan actually puts a greater load on the engine. It has an electric motor which has to be driven by the electrical system which gets it's power from the alternator(another belt).
Since the fan clutch is temperature controlled and there are no other systems to drive; it is most likely the most efficient system when in working order.

If you add up all the things require to run the mechanical fan vs the electric fan; the mechanical is simpler and by virtue of it's design has to suck less power from the engine.
June 04, 2009 09:31PM
Careful, Peter. I'm sure you remember, I got flamed for posting just such a comment on the old forum. smiling smiley

Tyler, I would take that bet. A properly adjusted V-belt can have an efficiency in the high 90's. How efficient is the electric motor you would use in that set-up? And you also have to account for the losses from converting the power from crank rotation to electric.

In either case, the exact same amount of energy is going to be needed to turn the fan. It's all in how efficiently you can get that energy to the fan.

Lucky for Rick that was all engineering. No science involved at all. smiling bouncing smiley

John
June 04, 2009 10:23PM
I'm not worried...it's all about collective losses.
With the mechanical fan, there is only the main loss in the clutch. With the electric fan there are losses in the fan motor, the wiring and the alternator.
The more pieces you put between the fan blade and the engine that ultimately turns it, the more losses there are.

I'll stand by my and your deductions thumbs up
June 04, 2009 10:32PM
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John Yust
Careful, Peter. I'm sure you remember, I got flamed for posting just such a comment on the old forum. smiling smiley
John

I totally agree with Peter. But can I flame him anyway, just for old times' sake??
hot smiley
rkj
June 04, 2009 11:08PM
I was only concerned about the actual reliability of the thing, the fan is such an important component, I think Bmw did a fair job working it out. I've always liked the idea of a second electrical fan in front of the condenser though, but I think we have one of those, right? B) but is yours working?

Rick
June 04, 2009 11:18PM
Thanks Simon,

Consider me appropriately flamed smileys with beer
June 04, 2009 11:20PM
The aux fan is only there with the A/C option.
Most of them don't work any more; either because the inline resistor is toast or; like mine; the motor is toast. sad smiley
June 05, 2009 11:51AM
There are three reasons I have heard for running an electric
1. they don't take power from the motor
2. they move more air
3. they are smaller making it easier to move around the engine bay

Mostly I want to do this because I have another daily, lots of time, and a good fan sitting in the garage.
I cant see how putting more strain on the alternator could be an issue. If the electric fan is a more efficient motor and the alternator puts out at a range of current depending on rpm as long as you collectively stay below the min out put of the alternator you should be able to add all the superfluous electronics you want with out putting more strain on the alternator. This is unless my understanding on the way an alternator works is completely wrong but engine rpm is the determining factor or alternator out put not load.

Jack
June 05, 2009 01:22PM
Well, they do take power from the engine and that power comes from the alternator. The net power used by an electric fan will be greater than by the mechanical one with the fan clutch...if both are in proper working condition and thermostatically controlled.

Whether they move more air is irrelevant...the engine only needs so much air to keep the radiator cooling enough that it doesn't get too hot for the thermostat to control it. That's why it's best to have it automatically controlled.

Placement is limited to in front or in back of the radiator...both places are limiting in the size of fan that can be mounted.
June 05, 2009 02:44PM
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jl1371
There are three reasons I have heard for running an electric
1. they don't take power from the motor
Of course they do. Where else would the power come from?

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jl1371
If the electric fan is a more efficient motor...
Yes, a simple electric motor is more "efficient" in converting energy to useful mechanical motion, compared to all the thermal losses inherent with a gasoline fed engine.

However, using a gasoline fed engine, to crank an alternator, to generate the electricity, that is either stored in a battery for later use or fed directly to the electric motor to turn a fan, is NEVER going to be more "efficient" than using the same gasoline fed engine to turn the same fan directly.
June 05, 2009 02:55PM
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jl1371
you should be able to add all the superfluous electronics you want without putting more strain on the alternator.
Not true.

The more electrical stuff you power with your alternator, the harder it becomes to crank the alternator.

You can feel that when the engine is idling happily with no load on it and then you turn on the headlights with full high beams. The revs drop momentarily as the alternator suddenly loads up trying hard to pump all those extra electrons into the circuit before the idle controller eventually notices the dropping revs and kicks in with more air/fuel to raise the idle speed back up where it belongs.
June 05, 2009 05:34PM
Sorry by power I meant the drop in power to run the mechanical fan vs the electric fan. So you have lost less hp to run the electric fan. I would think the added drag on the alternator to power the fan would be less then the added drag of running the mechanical fan. I agree it is a less "efficient" of a set up.
June 05, 2009 06:51PM
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jl1371
Sorry by power I meant the drop in power to run the mechanical fan vs the electric fan. So you have lost less hp to run the electric fan. I would think the added drag on the alternator to power the fan would be less then the added drag of running the mechanical fan. I agree it is a less "efficient" of a set up.
Would you agree that It takes a certain amount of effort to keep either fan turning in order to move the same amount of air? The required fan power to deliver the same amount of air should be the same in either case.

Whether that amount of required horsepower is provided directly via a belt mechanically driven off the engine, or whether that horsepower is provided indirectly by the engine via a belt driving an alternator to provide electricity to drive an electric motor to then mechanically spin the fan, the same of amount of horsepower will still be consumed at the tail end of the process by the fan itself.

But, because of the extra added steps involved in first transforming the engine horsepower into electrical power then reconverting it back to mechanical power via an electric motor, clearly the electric fan will ultimately consume more gasoline for a given airflow rate than would a simple mechanical fan driven directly by the engine.

I can see it making a difference if the mechanical fan is constantly driven, whereas the electrical fan can be switched on and off as needed. But the mechanical fan in the E30 is attached at the front of the engine to the constantly driven water pump via a viscous clutch which engages/disengages automatically as needed.

The only real advantage of electrically driven fans is in typical FWD vehicles where the engines sit sideways in the engine compartment, rather than conveniently longitudinal as in our RWD cars. It's much harder to rig a mechanically driven fan with the typical FWD layout, thus the requirement for the added complexity of an electric fan in those cars.
June 05, 2009 09:42PM
I always thought that all electrical components ran off the battery and the alternator just kept the battery charged up. If this is the case would not the drag on the motor be the same at all times as the alternator does not get harder to turn when there is a larger draw on the system. The voltage regulator is what determines how much actual power is reaching the battery to keep it charged. The alternator is capable of producing 90 amps at all times whether it is being used or not.
June 05, 2009 11:25PM
When the engine is not running; the electrical components are driven off the battery. When the engine is running, the electrical components are powered by the alternator with the battery acting as nothing more than a giant capacitor of filter.

with the engine running, any electrical component turned on will create additional drag(load) on the alternator. As Ferd points out, turning on the headlights will cause an initial drop in rpm do to the added load on the alternator.
The alternator may be capable of producing 90 Amps continuously but it really only produces what the load requires. If there is no load on it, there will be little power generated and conversely with a heavy load, more power will be generated.

The voltage regulator is in the circuit simply to regulate the voltage levels seen by the battery and the electrical components. Without the regulator, the alternator will produce varying voltage levels as the rpm rise and fall. If the voltages rise too high, they can damage the electrical and/or electronic components.

The battery is mainly in cars today so that we can operate the electric starter or listen to the radio when the engine is off. Early autos with no electric starters didn't have batteries; they had either generators or magnetos to operate the electrical components.

To summarize:

Electric fans will use more engine power than thermostatically controlled mechanical ones, given that they are to move the same volume of air.
Adding electrical components to the circuit will create a greater load on the alternator and thus the engine.

There is no free lunch sad smiley
June 06, 2009 12:51AM
So I'm abroad in Seattle and not replying because all I have is my ipod. But here it goes anyway, short and sweet.

I understand what had been said so far, and the logic is sound. but the one thing being left out, that I always thought was the biggest deal, is the loss of power to a belt driven system with a pully. There is resistance there which consumes power. If the fan is transfered to the pully driving the alternator, than that resistance is overcome already. In otherwords, if there was no loss of power in the transfer from mech-elec than an electric fan should be more efficient, right?
June 06, 2009 09:31AM
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Earendil
So I'm abroad in Seattle and not replying because all I have is my ipod. But here it goes anyway, short and sweet.

I understand what had been said so far, and the logic is sound. but the one thing being left out, that I always thought was the biggest deal, is the loss of power to a belt driven system with a pully. There is resistance there which consumes power. If the fan is transfered to the pully driving the alternator, than that resistance is overcome already. In otherwords, if there was no loss of power in the transfer from mech-elec than an electric fan should be more efficient, right?

That would be an incorrect assumption.
Also, the additional resistance of the alternator itself is added to the sum total.

If we could build an electric motor that had to be powered by the engine that produced no resistance and no losses, we would have created a perpetual motion machine...unfortunately the laws of conservation of energy don't allow that sad smiley
rkj
June 06, 2009 04:20PM
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Archeo-peteriX




If we could build an electric motor that had to be powered by the engine that produced no resistance and no losses, we would have created a perpetual motion machine...unfortunately the laws of conservation of energy don't allow that sad smiley

But peter, couldn't we work that out some way, even if it was not totally pure; something like the Chevy VOLT, but better! I think that thing runs on an electric motor that, after the batts wear down, keeps running on a small gas motor.

Seems like with all the new (and old) technology we could put an almost perpetual motion car together.

Maybe Cab could be in on it smiling smiley or anyone with ideas eye rolling smiley

Rick
June 06, 2009 04:31PM
If the auto industry was willing to tell the oil guys to take a hike, we would be light years ahead of where we are right now. Until then the oil guys will continue to poopoo al other forms of power with marketing and lies. Most people today don't realize that electric powered vehicles are more efficient than internal combustion engines and can produce more hp and way more torque for a given size. Don't buy into all the crap about producing electricity as being dirty. If the energy is collected from solar, wind, tide, wave or other natural sources, it is clean with no byproducts like coal fired generating planrts.

My impression of the Chevy Volt is that it is an electric car with a gasoline battery charger...not sure if the gas engine actually drives the car directly or not; most likely not.

Chances are we may never find out...once the GM executives have divied up and squandered the 50 Billion hand out, the company will be completely dead and gone with the stock holders owning 62% of a defunct company sad smiley



Edited 1 time(s). Last edit at 06/06/2009 04:34PM by Archeo-peteriX.
rkj
June 06, 2009 05:20PM
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Archeo-peteriX
If the auto industry was willing to tell the oil guys to take a hike, we would be light years ahead of where we are right now. Until then the oil guys will continue to poopoo al other forms of power with marketing and lies. Most people today don't realize that electric powered vehicles are more efficient than internal combustion engines and can produce more hp and way more torque for a given size. Don't buy into all the crap about producing electricity as being dirty. If the energy is collected from solar, wind, tide, wave or other natural sources, it is clean with no byproducts like coal fired generating planrts.

My impression of the Chevy Volt is that it is an electric car with a gasoline battery charger...not sure if the gas engine actually drives the car directly or not; most likely not.

Chances are we may never find out...once the GM executives have divied up and squandered the 50 Billion hand out, the company will be completely dead and gone with the stock holders owning 62% of a defunct company sad smiley

I think you're right, its just a charger of sorts that keeps the car going, but hey, that's not so bad. Not until we figure out something better!

Wonder if Cab has found new battery technology yet. That would help tremendously thumbs up

50 billion, just think what we could do with that money Peter, if nothing else we could send those money grubbing Arabs packing!
June 06, 2009 06:33PM
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Earendil
the one thing being left out, that I always thought was the biggest deal, is the loss of power to a belt driven system with a pulley. There is resistance there which consumes power.
True. One might think it would be better to bolt the fan directly to the end of the crankshaft thereby avoiding the power loss of a belt driven system.

However, the small parasitic loss of the drive belt is worth it because of the greater advantage of using a large pulley on the crankshaft and a small pulley at the fan, and connecting the two with a flexible belt, thereby making it possible to drive the fan (and water pump) at a higher rpm than the crankshaft speed in order to better pull air (and pump water) through the rad when the fan is needed most, i.e. when the engine is idling at low rpm with the car stopped in traffic.

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Earendil
If the fan is transfered to the pulley driving the alternator, then that resistance is overcome already. In other words, if there was no loss of power in the transfer from mech-elec then an electric fan should be more efficient, right?

No. If there was no loss in the extra steps required to convert from mechanical to electrical and then back to mechanical power, the best that could be said is that the electric fan is only as good as the mechanical fan.

It requires a certain amount of power to pull a given amount of air through the rad. The fan itself requires exactly the same amount of power, regardless of whether it is driven by an electric motor or driven by a gasoline motor.

You could drive the fan directly with the gasoline motor which will consume a certain amount of fuel. Or you could use that gasoline engine to drive a water pump, which would pump water uphill to fill a reservoir, from where the water would flow downhill by gravity through a turbine, which spins a shaft, which drives a generator, which generates electricity, which is pumped via a long extension cord from Niagara Falls all the way across the country to Oregon, where the cord is plugged into an electric motor, which then drives the same fan which will still require the exact same amount of power to pull air through the radiator.

In both cases, at the tail end of the process, the fan ultimately consumes the same amount of power. Only if there were no energy losses whatsoever involved in pumping the water, spinning the turbine, pumping electricity across the country through an extension cord, etc, etc, then you could say the gasoline motor powering the fan consumes exactly the same amount of fuel in either case, meaning the electric fan is only exactly as efficient as the mechanical fan driven directly by the gasoline engine.

But nothing is 100% efficient. Energy is lost at each extra step along the way. Obviously in this extreme example more gasoline would be consumed driving the electric fan than driving the mechanical fan directly. It's the same principle, only on a smaller scale, in your engine compartment.
June 06, 2009 11:01PM
What a great discussion! If I may wade in...

I had always thought that unless you were on a maniacal horsepower chase, there is no benefit in swapping to an electric fan. Basically because of what Ferd has pointed out: every time you add another component which converts energy, you get losses. So going mechanical (engine rotation) > belt > fan is always going to be more efficient than adding the extra conversions for an electric fan.

But here's something to think about: even if there is no electrical load, the alternator is always spinning, so it is always putting some drag on the engine (maybe only a very small amount though). Anyway, perhaps the INCREASE in drag of the alternator caused by the amps of the fan is less than the drag force of a mechanical fan driven through a clutch. I'm not saying it is, but just it's a possibility.

It's kinda similar to how we shouldn't pay for electricity we use in the middle of the night. The power stations need to keep running (it's a massive deal for them to shut down and restart) so they will be still using fuel regardless of whether we are using the power or not. Actually, that's a slightly different situtation, but I wanted to share the story anyway!!

Hey Jack, my understanding from basic electrical principles is that the maximum output current of an alternator is related to revs, but an alternator will cause more drag on an engine when it is charging the battery than when it isn't. So adding an electric fan might cause the alternator to be charging for an extra 5% of the time (I made that number up) and that's what you've got to compare against the extra drag of the mechanical fan. Perhaps we should write in to Mythbusters... or use your car as a test rig...
June 08, 2009 02:16PM
I am not telling anyone they are wrong, I'm just opening this up for further discussion because I love this stuff. Also, I didn't feel like I got my point across before using a little dinky iPod interface.

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Ferdinand
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Earendil
the one thing being left out, that I always thought was the biggest deal, is the loss of power to a belt driven system with a pulley. There is resistance there which consumes power.
True. One might think it would be better to bolt the fan directly to the end of the crankshaft thereby avoiding the power loss of a belt driven system.

However, the small parasitic loss of the drive belt is worth it because of the greater advantage of using a large pulley on the crankshaft and a small pulley at the fan, and connecting the two with a flexible belt, thereby making it possible to drive the fan (and water pump) at a higher rpm than the crankshaft speed in order to better pull air (and pump water) through the rad when the fan is needed most, i.e. when the engine is idling at low rpm with the car stopped in traffic.

This same pulley system for increased fan speed could be implemented with an electric fan though, right? Or else crank the electric motor up. IN other words there isn't any great advantage to this gear system over using an electric fan, only compared to directly attaching the fan to the end of the crank shaft.
I was trying to relate what I said above, a loss of power due to a belt and pulley, to what I said below, about the total loss of energy.

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Ferdinand
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Earendil
If the fan is transferred to the pulley driving the alternator, then that resistance is overcome already. In other words, if there was no loss of power in the transfer from mech-elec then an electric fan should be more efficient, right?

No. If there was no loss in the extra steps required to convert from mechanical to electrical and then back to mechanical power, the best that could be said is that the electric fan is only as good as the mechanical fan.

It requires a certain amount of power to pull a given amount of air through the rad. The fan itself requires exactly the same amount of power, regardless of whether it is driven by an electric motor or driven by a gasoline motor

Okay, we agree that the fan, no mater how it is powered, requires the same amount of energy.
We also agree that all power in a running car initially comes from the mechanical turning of the engine.
The question is what path that energy takes, and where any loss (inefficiencies) there are in that path.

It seems to me that in a strictly mechanical situation (i.e. our stock cars), you have a loss of energy when
1. you use a mechanical belt, and two pulleys.

In a mechanical to electrical system you have loss
1. making that conversion
2. Any loss to the transfer of current through a wire
Since you are using a belt/pulley system that is already spinning regardless of the attachment of an electrical fan or not, the belt/pulley friction is already out of the equation.

It seems the entire ordeal rests and which one creates a greater loss of energy, two pulleys and a belt, or the transfer of mechanical to electrical. If what I have listed are the only differences in the two systems, than this is why I stated that I thought a system with no loss of energy due to a transfer, would result in a more efficient system than two pulleys and a belt.

I'm okay with being informed that one energy loss is far greater than the other. But let's not pretend that one system is the exact same as the other, with a few more losses in power. They appear to both have they own unique ways of losing energy in the system, thus we need to compare those inefficiencies in each particular system.

In either case, we're talking about mere fractions of a horsepower smileys with beer



Edited 2 time(s). Last edit at 06/08/2009 02:21PM by Earendil.
June 08, 2009 05:17PM
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Earendil
...

In either case, we're talking about mere fractions of a horsepower smileys with beer

I think you will find the losses in the alternator itself are greater than fractions of a hp. Under full load, the alternator could be consuming several hp just to build the magnetic field in it's coils.

There is no free lunch winking smiley
June 08, 2009 06:11PM
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Earendil
Since you are using a belt/pulley system that is already spinning regardless of the attachment of an electrical fan or not, the belt/pulley friction is already out of the equation.
Agreed. Whether you use the belt/pulley to drive a fan, or to drive an alternator to power an electric motor to spin the fan, the friction losses due to the belt itself should be very similar.

It seems that some people believe an alternator somehow provides free energy.

If there is no electrical load on the alternator, then yes it takes very little torque to keep it spinning. There will be some small energy loss due to the belt friction driving it, and some windage loss from the cooling fan on the alternator, but otherwise if it's not producing any current the alternator spins relatively effortlessly. But, the more electrical devices you try to power from the alternator, the harder it becomes to spin it and the more torque is required to force it to turn.

It takes work, horsepower, to generate the required electrical power.

The only way an electrically driven fan would use less fuel, compared to driving it mechanically directly from the engine, is if the electric fan is powered by a totally separate battery that has been charged by some external source, even ignoring the fact that the gasoline engine now has to schlep around the extra weight of this battery. But, if you are using the same gasoline engine to drive an alternator to charge the battery or directly run the electric motor that eventually powers the electric fan, then you've gained nothing whatsoever over simply powering the fan directly from the engine. In fact, it is significantly less efficient because of the extra steps involved, each one of which involves further losses.
June 08, 2009 06:21PM
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Archeo-peteriX
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Earendil
...

In either case, we're talking about mere fractions of a horsepower smileys with beer

I think you will find the losses in the alternator itself are greater than fractions of a hp. Under full load, the alternator could be consuming several hp just to build the magnetic field in it's coils.

There is no free lunch winking smiley

Right, but the portion of that that is due to the fan is a fraction of a horsepower ;-)
13.6 volts * 90 amps is about 1.6 horsepower.

A trip over to wikipedia sites a source saying that car alternators have an efficiency between 50% and 62%.
So worst case an alternator will eat 3.2hp, plus other resistance associated with the pulley system.

Does this sound about right?

Pretty bad conversion rate there for energy, aye? smiling smiley

~Tyler


edit* of course 3.2hp is only if the alternator is rated for 90amps, and it is attached to something drawing all 90 amps. I doubt our cars use close to 90 amps in normal operation, at least not if the battery is charged.

edit x2
I'm slapping a huge approximation disclaimer sticker on this post smiling smiley



Edited 2 time(s). Last edit at 06/08/2009 06:35PM by Earendil.
June 08, 2009 07:02PM
There are some good reasons to use an electric fan, like in the case of FWD vehicles with their engines placed sideways in the engine compartment. But even in our E30s, if it is a/c equipped it will have an auxiliary electric fan placed ahead of the a/c condenser ahead of the radiator. That electric fan should come on automatically whenever the a/c is engaged, or whenever the coolant temp exceeds a certain level.

Even though there undeniably are efficiency losses in converting gasoline to mechanical energy to driving an alternator to create electricity to then reconvert the electricity back to mechanical energy via the electric motor to drive the auxiliary fan, it's much simpler than trying to rig a complicated mechanical drive around or through the radiator.

There are other ways that an electric drive is more desirable, regardless of the efficiency losses, such as in diesel locomotives. Huge diesel engines power the locomotive, but the problem is that piston engines will only make useful torque and power at some non-zero rpm. They can't pull anything from a standstill without slipping a clutch somewhere in the driveline. If you're trying to pull a heavily loaded train from a standstill, you're going to be burning clutches something fierce.

So, instead the locomotive uses the powerful diesel engine to drive a generator that powers an electric motor to pull the train. Electric motors are ideally suited for this purpose because they create maximum torque from a standstill and don't require a clutch.

Hybrid gasoline/electric motors are more efficient at using fuel only because the gasoline engine can be run constantly at its optimum fuel efficient rpm, rather than constantly varying engine speed up and down through different gears, to charge a battery or run a generator that in turn powers an electric motor to drive the vehicle.

The biggest fuel efficiency benefit though is in using the electric motor in reverse to put a big load on it to charge the battery in regenerative braking. Rather than just burning up the car's kinetic energy in heating the brake rotors, that energy is put to use instead recharging the battery. The torque required to turn the motors into generators is used to slow the car.

In big diesel locomotives they also use the electric drive motors as brakes, simply by using the motors as generators to drive current through huge resistors, "waffle plates", that glow red hot. It requires enormous brake torque to pump the current that causes those waffle plates to glow hot. In that way they convert the kinetic energy of the train into heat which is dumped to the atmosphere.
June 08, 2009 07:03PM
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Earendil

A trip over to wikipedia sites a source saying that car alternators have an efficiency between 50% and 62%.
So worst case an alternator will eat 3.2hp, plus other resistance associated with the pulley system.

What about the efficiency of an electric motor of the size required to run the fan? I looked up the v-belt efficiency and I asked you about the electric motor efficiency way back at the beginning of this this thread. You're the electrical engineering student, so I thought you might have that info handy. I'm the mechanical engineer, so I took care of the v-belt. Ferd is obviously the saintly teacher because nobody but a Saint or a teacher would have the patience to explain something as many times as he has in this thread. Good explanations too. Anyway, what's the efficiency of that motor?

John
June 08, 2009 08:19PM
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John Yust
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Earendil

A trip over to wikipedia sites a source saying that car alternators have an efficiency between 50% and 62%.
So worst case an alternator will eat 3.2hp, plus other resistance associated with the pulley system.

What about the efficiency of an electric motor of the size required to run the fan? I looked up the v-belt efficiency and I asked you about the electric motor efficiency way back at the beginning of this this thread. You're the electrical engineering student, so I thought you might have that info handy. I'm the mechanical engineer, so I took care of the v-belt. Ferd is obviously the saintly teacher because nobody but a Saint or a teacher would have the patience to explain something as many times as he has in this thread. Good explanations too. Anyway, what's the efficiency of that motor?

John

Humm. I'm a computer science graduate, not an electrical engineer student. I'd love to graphically model and run calculations on this electrical magic using software, if you provide me with an electrical engineer smileys with beer
If you asked ME specifically about efficiencies, my apologies for missing that question. However, I've never studied this matter, and did not known until I went looking around the internet for it. I took some basic physics classes, so I'm well aware of the laws of conservation of energy, and myths of perpetual motion machines etc etc. But I certainly never studied applications of these laws past 60 second examples.

Ferd is quite informative, and if I might say, very good at getting information across in a written format.



Edited 1 time(s). Last edit at 06/08/2009 08:24PM by Earendil.
June 08, 2009 08:48PM
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Earendil


Humm. I'm a computer science graduate, not an electrical engineer student. I'd love to graphically model and run calculations on this electrical magic using software, if you provide me with an electrical engineer smileys with beer
If you asked ME specifically about efficiencies, my apologies for missing that question.

Oh, sorry. I didn't mean to insult you like that. smiling smiley I thought I remembered something about EE from a while ago, but I was obviously mistaken.

I didn't really ask you specifically, but since I was operating under the misconception that you had been studying EE, I though bringing it up would remind you about all the efficiency related EE problems you had been solving in the engineering courses you weren't taking. (Did you follow that? It was confusing to type - maybe it's the beer).

I'm having IPA I made that's loaded with hops from the PNW. smileys with beer

Oh yeah, electric motors are about 95% efficient. V-belts are equal to or better than that when they're adjusted right, but probably not as good if the belt is slipping. Then you have the conversion to electric and back to rotation with the motor, but surely we all know that by now.

John
June 08, 2009 09:07PM
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John Yust
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Earendil


Humm. I'm a computer science graduate, not an electrical engineer student. I'd love to graphically model and run calculations on this electrical magic using software, if you provide me with an electrical engineer smileys with beer
If you asked ME specifically about efficiencies, my apologies for missing that question.

Oh, sorry. I didn't mean to insult you like that. smiling smiley I thought I remembered something about EE from a while ago, but I was obviously mistaken.

I didn't really ask you specifically, but since I was operating under the misconception that you had been studying EE, I though bringing it up would remind you about all the efficiency related EE problems you had been solving in the engineering courses you weren't taking. (Did you follow that? It was confusing to type - maybe it's the beer).

I'm having IPA I made that's loaded with hops from the PNW. smileys with beer

Oh yeah, electric motors are about 95% efficient. V-belts are equal to or better than that when they're adjusted right, but probably not as good if the belt is slipping. Then you have the conversion to electric and back to rotation with the motor, but surely we all know that by now.

John

Apology accepted, and I understand what you're saying despite what is surely an amazing IPA smileys with beer

So for anyone who comes across this thread later, I think I can sum up what our collective musings have determined.
(Ferd may feel free to reword anything in a more eloquent many if he sees fit)

Perpetual motions machines aint happening. If you think they can, stop reading now and go build one.

...now that those fools are busy, we may proceed.

The mechanical belt systems operate at about 90% efficiency, where as an electric motor operates at about 95% efficiency.
Seemingly making an electric motor solution more energy effective.
However, there is a 50-62% loss of energy in the alternator in transforming the mechanical energy to electrical energy.

Until we can produce an alternator with better than 95% efficiency, an electrical fan will not put more horses to the wheels.
However as noted by Ferd, there are many good reasons to use an electric motor, just none of them have to do with being more energy efficient, but are based in practicality.

Did I miss anything or misrepresent anything?
June 10, 2009 01:05PM
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Earendil
The mechanical belt systems operate at about 90% efficiency, where as an electric motor operates at about 95% efficiency.
Seemingly making an electric motor solution more energy effective.
However, there is a 50-62% loss of energy in the alternator in transforming the mechanical energy to electrical energy.

Until we can produce an alternator with better than 95% efficiency, an electrical fan will not put more horses to the wheels.
However as noted by Ferd, there are many good reasons to use an electric motor, just none of them have to do with being more energy efficient, but are based in practicality.

Did I miss anything or misrepresent anything?

Just one thing to add. Yes, an electric motor probably does operate more efficiently than a mechanical belt system. But obviously one gains nothing by still using the same mechanical belt system to drive an alternator to power the electric motor. In that case it makes more sense to use the belt system directly.

An electric motor is certainly a better mechanism for driving things, but you need to consider how and where the energy is coming from to provide the required electricity, It's much the same case that's being made to promote the use of hydrogen as a miracle fuel to save the planet. There's no arguing that hydrogen burns cleaner than fossil fuels, producing nothing but clean energy and water as byproducts. It's practically miraculous.

However, hydrogen is not an energy "source". It, like pretty much any other fuel, is merely an energy "storage" medium. Hydrogen does not grow for free on trees, and contrary to popular belief, hydrogen does not lie idly in every lake and ocean waiting to be poured straight into your fuel tank. No matter how attractive hydrogen is as a fuel, it doesn't come for free.

Every school kid knows that hydrogen can be produced by electrolysis, splitting water into hydrogen and oxygen. From there, gullible people can easily be led to believe that the oceans will provide an endless supply of hydrogen. However, the electrolysis process consumes more energy to split the hydrogen from water than can be usefully recovered later in burning the hydrogen to power your homes and cars. The energy to drive the electrolysis process has to come from somewhere. You've gained nothing if you're burning fossil fuels in a power station to generate the electricity necessary to power the electrolysis process to provide hydrogen to heat your home. It is far more efficient to bring the fossil fuels directly to your furnace.

Currently, by far the cheapest and most plentiful source of hydrogen is natural gas. Burning more natural gas even provides the power required to strip the hydrogen out of this abundant hydrocarbon fuel. However, at the end of the process you're left with an amount of hydrogen containing less than 50% of the energy that was contained in the original amount of natural gas. Where's the sense in that? Why not just use the natural gas directly?

Strictly speaking, not even hydrocarbon fuels are an energy "source". They were originally plant and animal matter that died, then collected in sufficient quantities under the right conditions to cook for millions of years and eventually form pools of oil. Those plants and animals fed off each other, all ultimately fuelled by the weak energy cast on them by the far away sun. In effect, all hydrocarbon fuels are an energy "storage" medium for condensed, collected, and highly concentrated -- sunlight!

We will continue to tout miracle fuels like hydrogen or bio-fuels or hybrids, simply because we still can. But, as we ever more rapidly consume the easily harvested reservoirs of energy-dense petroleum products, very soon we will eventually need to find ways to capture energy more efficiently directly from the sun.
June 10, 2009 05:33PM
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Ferdinand
We will continue to tout miracle fuels like hydrogen or bio-fuels or hybrids, simply because we still can. But, as we ever more rapidly consume the easily harvested reservoirs of energy-dense petroleum products, very soon we will eventually need to find ways to capture energy more efficiently directly from the sun.

Or mimic the sun by going nuclear!

Energy-dense petroleum products are only an advantage when the energy source needs to be portable, such as vehicles. So far we haven't been able to capture solar energy (solar panels) directly to the moving device in sufficient quantity for that to be practical or to satisfy performance requirements. But that could come!

Salut, Bob p.
June 20, 2009 08:39PM
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Earendil
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John Yust


Apology accepted, and I understand what you're saying despite what is surely an amazing IPA smileys with beer

So for anyone who comes across this thread later, I think I can sum up what our collective musings have determined.
(Ferd may feel free to reword anything in a more eloquent many if he sees fit)

Perpetual motions machines aint happening. If you think they can, stop reading now and go build one.

...now that those fools are busy, we may proceed.

The mechanical belt systems operate at about 90% efficiency, where as an electric motor operates at about 95% efficiency.
Seemingly making an electric motor solution more energy effective.
However, there is a 50-62% loss of energy in the alternator in transforming the mechanical energy to electrical energy.

Until we can produce an alternator with better than 95% efficiency, an electrical fan will not put more horses to the wheels.
However as noted by Ferd, there are many good reasons to use an electric motor, just none of them have to do with being more energy efficient, but are based in practicality.

Did I miss anything or misrepresent anything?

This is all very well, but nobody went into this: WHEN is the energy used.

The fan is an auxiliary method to cool the radiator only when the car is stopped, or moving slowly.
Then, you are not very concerned about that little amount of power, cause you have the engine idling anyway.
When the car is moving at speed, or starting from completely cold, the electric fan is completely shut off, while the mechanical one keeps going. Thats why BMW introduced the fan clutch, to save some power by slipping and letting the fan run slower than it would if directly driven by the pulley. sadly, the fan clutch is the weak link, it will eventually fail and be replaced several times through the car useful life.

As for electric fans, those are operated by a thermostat switch mounted somewhere on the radiator or thermostat casing, it monitors the water temperature and turns the fan on and off automatically. Can't think why anyone would want a manual override...
Eventually it may fail, it will probably be the thermostat which is rather inexpensive and easy to replace.
As for the electric power needed, your car has an alternator turning anyway, so the extra resistance needed to produce a little extra power for the fan is about the same either way, at the alternator belt or at the fan clutch.
June 20, 2009 11:27PM
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Jose Pinto
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Earendil
Quote
John Yust


Apology accepted, and I understand what you're saying despite what is surely an amazing IPA smileys with beer

So for anyone who comes across this thread later, I think I can sum up what our collective musings have determined.
(Ferd may feel free to reword anything in a more eloquent many if he sees fit)

Perpetual motions machines aint happening. If you think they can, stop reading now and go build one.

...now that those fools are busy, we may proceed.

The mechanical belt systems operate at about 90% efficiency, where as an electric motor operates at about 95% efficiency.
Seemingly making an electric motor solution more energy effective.
However, there is a 50-62% loss of energy in the alternator in transforming the mechanical energy to electrical energy.

Until we can produce an alternator with better than 95% efficiency, an electrical fan will not put more horses to the wheels.
However as noted by Ferd, there are many good reasons to use an electric motor, just none of them have to do with being more energy efficient, but are based in practicality.

Did I miss anything or misrepresent anything?

This is all very well, but nobody went into this: WHEN is the energy used.

The fan is an auxiliary method to cool the radiator only when the car is stopped, or moving slowly.
Then, you are not very concerned about that little amount of power, cause you have the engine idling anyway.
When the car is moving at speed, or starting from completely cold, the electric fan is completely shut off, while the mechanical one keeps going. Thats why BMW introduced the fan clutch, to save some power by slipping and letting the fan run slower than it would if directly driven by the pulley. sadly, the fan clutch is the weak link, it will eventually fail and be replaced several times through the car useful life.

As for electric fans, those are operated by a thermostat switch mounted somewhere on the radiator or thermostat casing, it monitors the water temperature and turns the fan on and off automatically. Can't think why anyone would want a manual override...
Eventually it may fail, it will probably be the thermostat which is rather inexpensive and easy to replace.
As for the electric power needed, your car has an alternator turning anyway, so the extra resistance needed to produce a little extra power for the fan is about the same either way, at the alternator belt or at the fan clutch.

Good point about when the energy is used thumbs up

But there can be considerable energy draw from the alternator when the fan does turn on. The fan always operates at it's maximum designed speed and as has been pointed out, this will consume more than a little power.

The mechanical fan, thru the clutch, will use varying amounts of energy from the engine as it slips more or less depending on the temperature.

In the end, it's hard to say which system uses more energy but I suspect it is still going to be the electric fan smiling smiley
June 21, 2009 01:31PM
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In the end, it's hard to say which system uses more energy but I suspect it is still going to be the electric fan

Now thats an easy one.
The electrical fan can be set up to work in two speeds, half speed at a given temperature range, and full speed above certain temperature, shut off when not needed.
Power consumption for electric fan would be P (fan power) * time at full speed, P/2 * time at low speed, 0 when shut off.
Power consumption for fan clutch is P*(clutch factor) , where the clutch factor ranges from a low value, when fan is unneeded but is turning at slow speed, and near one, when all temperature is hot and the clutch engages completely.
P should be the same or similar for either fan, the power needed to move enough air to the radiator.
I suspect the fact that fan clutch is always turning, while electric fan is stopped most time, and seldom goes to high speed, offsets the advantage of the fewer energy transformations for the engine driven fan.
Now we only need to put figures on that "clutch function" over temperature and time to compare.

We had well established the difference in power consumption is very slim, and both setups are very reliable and simple enough.
June 21, 2009 02:59PM
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Jose Pinto
Quote
In the end, it's hard to say which system uses more energy but I suspect it is still going to be the electric fan

Now thats an easy one.
The electrical fan can be set up to work in two speeds, half speed at a given temperature range, and full speed above certain temperature, shut off when not needed.
Power consumption for electric fan would be P (fan power) * time at full speed, P/2 * time at low speed, 0 when shut off.
Power consumption for fan clutch is P*(clutch factor) , where the clutch factor ranges from a low value, when fan is unneeded but is turning at slow speed, and near one, when all temperature is hot and the clutch engages completely.
P should be the same or similar for either fan, the power needed to move enough air to the radiator.
I suspect the fact that fan clutch is always turning, while electric fan is stopped most time, and seldom goes to high speed, offsets the advantage of the fewer energy transformations for the engine driven fan.
Now we only need to put figures on that "clutch function" over temperature and time to compare.

We had well established the difference in power consumption is very slim, and both setups are very reliable and simple enough.

Without actual measured energy consumption of both systems, we can only make educated guesses.

I wonder if we could offset the power used by the electric fan if we had it generate electricity when it isn't being driven for cooling? Just set it up like the regenerative braking system in electric/hybrid cars. That would make it way more efficient than the mechanical fan which cannot produce anything but drag grinning smiley
June 21, 2009 07:36PM
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Without actual measured energy consumption of both systems, we can only make educated guesses.
Nope, it can be calculated. Where is Vlad Amuzescu when you need him?!

For the electric fan, see above, just multiply time on and power, thats the energy consumed. Then multiply by th efficiency of the alternator, and you get how much energy (KWh) was taken from the crankshaft to cool the engine, over a given period of time.

For the viscous clutch, just made some research, from a parts catalog:
" Hayden Fan Clutch 1995-1996 BMW 318ti
HAYDEN FAN CLUTCH -- 5.43 in. overall diameter, M24 x 1.5 left in. pilot diameter, 1.37 in. fan mount height, 4.88 in. fan bolt circle, M6 x 1.0 hole 4 bolt and nut threads, standard-duty thermal design, standard rotation; Turns the fan 60-70 percent of the shaft speed when engaged and 20-30 percent when disengaged; Used with 1-1/2 in. lighter pitch fans; Features flat plate impeller design with up to 11.4 sq. in. of working area, identified by a smooth steel faceplate and thermal spring assembly on the front side; With Hayden's limited 1-year warranty.
Fits: Standard (Clockwise) Rotation From Front Of Vehicle."

The bold is mine, is the interesting data.
So, as i suspected, the fan is always on, and it cant slip less than 70%, or more than 20%, at best. (lets assume 25%-65%).
Plus, from my reading, if the 65% slippage must draw enough air (car idling, 750rpm), then when you go at 6000 rpm (and you want to do that occasionally grinning smiley) and you get the minimum slippage, which is 25%, way more than needed to cool the radiator.
That means waste of power when you need it most, to pass that electrical fan cooled Honda crawling uphill in front of your fine car.
Not to mention when you go fast and don't need the fan at all, it still draws those 25% from the crankshaft, always.

So, back to the original point: the best setup depends on what you want to do with the car.

Simple setup - viscous fan clutch
Chasing the ultimate Watt (or hp)-electric
Overkill - both, like e30 with A/C
June 21, 2009 08:28PM
I agree...we want Vlad back!

I still think the only real answer to this question will be with actual measured energy consumption grinning smiley
June 21, 2009 09:46PM
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Without actual measured energy consumption of both systems, we can only make educated guesses.

C'mon, it's not that hard!

All we need is
- a rolling road dyno
- in a temperature controlled room
- a load cell to measure the mass of fuel used
- a white E30. White is more scientific.

Then you just run it with the fan clutch, swap to an electic fan, repeat and hey presto!

I suspect that someone, somewhere has already done this. Unfortunately it wasn't Mythbusters because I doubt it would make good television...
August 01, 2009 12:18AM
Amazing, so much discussion about something hardly needed. My son's E-36 has no fan at all and does not over heat even on a track day. I had a E-30 318 that had a little front damage so removed the fan to keep it out of the radiator. It would only overheat if setting several minutes idling in the drive through line. In normal traffic it was fine. My E-30 325 has a very worn fan clutch that barley turns the fan above an idle speed and it never overheats. The electric fan for the AC never goes on high speed and only runs when the AC is turned on. Even idling in traffic on a hot day barely got past the middle of the temp gage. If one needs to run AC in stop and go traffic there has to be a fan to make the AC work for sure and standing at idle for more than a few minutes will cause a car to overheat. If someone was going up a steep hill at low speed, might wish for a fan that could be turned on as needed.

One benefit I see of an electric fan is that it is less likely one will put a finger into it.

My grandmother has a Lexus with (believe it or not) a hydraulic driven fan. The power steering pump powers the fan when the temp sensor tells it to. Even at idle, it really spins. Setting at idle in the driveway, it will cycle on and off every couple minutes. While driving, without AC it probably never comes on.

Bob in Everett
August 01, 2009 02:05PM
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Bob in Everett
Amazing, so much discussion about something hardly needed.

Bob in Everett

Hey, if you can't spend hours on the internet discussing (or arguing about) things that don't matter, then what's it good for? :confused:

John
August 01, 2009 09:40PM
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John Yust
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Bob in Everett
Amazing, so much discussion about something hardly needed.

Bob in Everett

Hey, if you can't spend hours on the internet discussing (or arguing about) things that don't matter, then what's it good for? :confused:

John

Trolling?
August 02, 2009 11:42AM
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Archeo-peteriX
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John Yust
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Bob in Everett
Amazing, so much discussion about something hardly needed.

Bob in Everett

Hey, if you can't spend hours on the internet discussing (or arguing about) things that don't matter, then what's it good for? :confused:

John

Trolling?

Same thing? smiling smiley

I have a few friends who enjoy sitting around with me and discussing/hypothasizing about things we only partially understand. I think it's something humanity could use a lot more of, as humans are generally able to figure a lot of stuff out, if they try for longer than 30 seconds eye rolling smiley

Though, I once had a room mate that when engaging in these sorts of discussions always started taking it personally and would get upset if I didn't agree with him in a relatively short period of time. I kept things superficial after a while smiling smiley

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

August 02, 2009 12:03PM
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Earendil
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Archeo-peteriX


Trolling?

Same thing? smiling smiley

The difference I see is that trolling is intended to cause trouble and what we've been doing with the electric motor and A/C threads (and others like them) is dig into the details of things that most people wouldn't be interested in.

Thread hijacking is when somebody changes the subject and heads off in another direction. Maybe even discussing something that should be on another forum. I sure wouldn't do that!winking smiley

John
August 03, 2009 05:10PM
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Archeo-peteriX
Quote
John Yust
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Bob in Everett
Amazing, so much discussion about something hardly needed.

Bob in Everett

Hey, if you can't spend hours on the internet discussing (or arguing about) things that don't matter, then what's it good for? :confused:

John

Trolling?

Reading old threads? hot smiley

Watching nude pictures is very popular as well, so I've heard...

smileys with beer
August 03, 2009 11:27PM
Ok, so maybe I sound like an old curmudgeon. Just seems like something as reliable as a mechanical fan would not be replaced by a bunch of complex electrical stuff that is more likely to cause a problem.

My primary job is designing hydraulic equipment and someone is always trying to replace some if with an electric gizmo that costs more and weighs more. The only advantage is that when the non-hydraulic thing leaks, the leak is a lot harder to find.

Bob in Everett
September 21, 2009 10:24PM
I have been out and about for most of the later months of the summer just came back to the real world hopped on. My surprise to see a question I asked months ago is still up at it. Hope everyone had a good and productive summer. And yes I will be taking out my fan and installing a slimmer electric fan, will report on how it FEELS. No imperial evidence here.
September 22, 2009 12:43AM
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jl1371
I have been out and about for most of the later months of the summer just came back to the real world hopped on. My surprise to see a question I asked months ago is still up at it. Hope everyone had a good and productive summer. And yes I will be taking out my fan and installing a slimmer electric fan, will report on how it FEELS. No imperial evidence here.

Well the thread was fun and educational, but I don't remember if we ever all agreed. What I think we did agree on is that the difference is a fraction of a hp. So when it comes to rubber on the road, you should only notice a placebo effect spinning smiley sticking its tongue out

-----------------------------------------------------------------------------------
1989 - E30 - M20 - Manual. Approximately 270,000 miles
2000 - E46 - M52TUB28 - Manual. Approximately 110,000 miles

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