isn't always a true statement. This is great in colder climates; in the south - not so much.
Yep, changing to an electric fan only moves the power draw to the alternator from the crank. Either way, energy doesn't come 'free' in an automotive environment.
Ok so wait, the engine not having to spin that fan doesn't increase/free up horsepower?
Moving the power draw to the alternator I don't believe makes the alternator any harder to turn, such as the A/C compressor when you turn the A/C on. I am having a hard time wrapping my head around these statements.. Now with all due respect to the above mentioned, I understand where an electric fan may not be the best solution for all situations, but for the question the OP has, I believe the correct answer is "YES", and electric fan will free up some HP and is not to difficult to accomplish with a few basic skills and maybe a little guidance from this forum.
I apologize up front - this is going to be long and I'm going to try to keep this simple ...
Start at the beginning. All 'energy' - just use that generically for the sake of keeping this short(er) - comes from somewhere. It just doesn't 'appear' out of thin air, so to speak. That's why there's no such thing as perpetual motion. That's the realm of 'Magical Thinking' where you get something from nothing - the realm most people on the Internet and most people above techs in IT live in. ;D ;D ;D
Petroleum is stored solar energy. From millions of years ago, but it's just chemically stored energy emitted by our sun.
Now, 1 gallon of gas (distilled petroleum) contains n amount of energy. That is a FIXED and FINITE amount. More energy can not be released than is actually stored.
Burning a gallon of gas in your Sport produces n horsepower (HP). Assume that conditions remain the same, again for the sake of keeping this short, it will always produce n HP - no more and no less.
That n HP is used to turn the wheels of your Sport. HOWEVER, that is not the entire picture. Some portion of n HP is used to turn your accessories - P/S, A/C, and, yes, the alternator and cooling fan, 'cause they're accessories - everything that isn't the engine proper.
Ok. Now, just like the engine when driving up hill and down hill, accessories don't always need the same n HP to successfully complete their tasks - but there is ALWAYS a minimum amount of energy used even when they're 'not doing anything' - I guess you could term that 'idling'.
An alternator works by spinning a bunch of magnets inside a wire 'cage' so to speak. The alternator is turned by a belt and pulley arrangement from the engine. As the alternator is spun by the engine it CONVERTS the energy from the combustion of gas into electricity. The electricity is stored in the automotive battery. It didn't create NEW energy, it just changed the form and storage medium. So, instead of having n energy stored in a liquid base, it's now stored in a battery as electrons, etc.
Now, it takes n HP to turn a fan - electric fan, manically fan, clutch fan - doesn't matter. 'n' changes depending on the speed the fan is rotated, the steepness of the blade pitch and some other things that aren't relevant here. The point is, some of the energy released in the combustion cycle is used to rotate the fan.
The HP requirements of a mechanical fan - think old school muscle car with four blades bolted directly to the water pump - is pretty linear. The HP required to turn it increases in a straight line in relation to engine revolutions per minute (RPM). So, when the engine is off it requires 0 HP, at 1000 RPM it requires 5 HP, at 2000 RPM it requires 10 HP, at 3000 RPM it requires 15, at 4000 it requires 20, and so on and so on. There's no variance because the relationship between the fan and engine is 1:1 - it's physically, 'hard' attached - just four blades bolted to the engine.
A 'clutch' or viscus fluid driven mechanical fan adds a variable to the mechanical fan. Temperature. Bear with me as I'm going to use 'clutch' generically to refer to all types of mechanical fans with some type of assembly that allows it to spin somewhat independently of the engine.
IN GENERAL - an automobile doesn't need a cooling fan a lot of the time. Some vehicles only need them when they're going slow or stopped in traffic. Some on the highway but otherwise they're fine. Some only need one in the dead of summer, but not at all in the winter. So, you can deduce - and engineers have - that turning a mechanical fan all the time is a waste of energy - that LIMITED, FINITE amount that you get from n gallon of petroleum.
Hence - the 'clutch' fan. The design of a clutch fan is such that it uses temperature in the engine bay to determine how fast it should be spinning and when. Sort of a 'smart' mechanical fan.
Unlike the HP use of a strict mechanical fan, HP use isn't linear. So, instead of 1:1 irrespective of the engine RPM, you can have 1:.5, 1:.1, 1:.9 or 1:1 at any RPM, depending on what the temperature is.
Typically, (simply put) clutch fans are designed so that they pull the most air at idle and low speeds and as the engine speed increases the fan speed decreases. Temperature is taken into account to decrease the fan speed at, say, freezing, and increase it at, say, 90. But, that's the general idea.
Note that nowhere does it say - the fan stops turning - because it NEVER does. Mechanical clutch fans require n HP even when technically 'disengaged'.
So, that's a cool and nifty idea but you might think 'clutch fans aren't very smart, how can they REALLY tell if I need a fan or not?' Well, they can't. In fact, they're pretty stupid and pretty limited, but they are more efficient than straight mechanical fans.
The electric fan is also pretty unintelligent. Like mechanical fans, they require n HP at x fan RPM. Always the same, never changes. The energy use is linear just like a mechanical fan.
Replacing a 'always on' mechanical fan with an 'always on' electrical fan is pretty much a wash. Remember, you have n HP to work with and not a decimal place more. All you'd be doing is trading use of the same energy needed to turn one and shunting it off to turn the other.
Enter the 'computer age'. Remember that people are computers, too, so the first computer controlled electric fan was an idiot behind the dash flipping a switch on and off while watching the temperature gauge. Yea? Don't laugh. That's still the mode of operation for a lot of electric fans in this country.
Take a giant leap sideways and now the electric fan(s) are controlled by the ECM/ECU/PCM - the automotive 'computer'. These computers can decide on a microsecond basis what speed your fan(s) should be running at, or if they should be running at all. If it's 20 below zero and you're heading into a head wind and the engine is barely capable of keeping itself up to operating temperature, the computer will decide that no fan is needed and shut it completely off.
The important point is that the fan 'adapts' to environmental current conditions 'on the fly'. This is probably one of the biggest breakthroughs in automotive engineering in the last 15 years. HOWEVER, when that fan(s) is on it STILL requires n HP to turn it.
This is the most important point I can make. Every accessory in your automobile requires energy to make it do what it does. The dome light, seat belt dinger, MP3 player, etc. - EVERYTHING.
As the electrical draw from an alternator increases so does the HP required to turn it. Remember - 'NO FREE LUNCH'. So, in this case, the more electricity you need, the more HP to turn the alternator, the more gas is required to produce the HP.
You can not, and I repeat, YOU CAN NOT get more out than you put in. Physics does not work like that no matter what the green duffuses living in the 'Realm of Magical Thinking' want you to believe.
OK. Now, here is where incorrect, incomplete and misinformation start.
"You can not increase your 'power' which in this case translates into usable (by something else) HP by replacing a mechanical or clutch fan with an electric fan."
That is correct. Remember? You can't get something for nothing.
But, that's wrong, because personally I've replaced my perfectly functioning stock clutch fan with a Ford Contour twin electric fan set and my mileage - which means HP - when up. So, somehow, I managed to get something for nothing out of the deal, right?
Wrong. The former is still correct. No something for nothing. Fine, I know what I saw, I have data to back it up so what's up?
Electric fans controlled by a computer - not Bob with a finger on a switch - are magnitudes more efficient than mechanical fans and clutch fans. Electric fans DO NOT USE LESS ENERGY THAN MECHANICAL OR CLUTCH FANS! They just use what they need a lot more efficiently so they can accomplish the same ends with less.
I want to make this clear, because it's a bone of contention and confusion elsewhere ...
When electric fans are installed to replace mechanical or clutch fans, they are not installed in a way to make them operated EXACTLY the same as the fans they replaced. In other words, no one installs an electric fan and just wires it straight to the battery to be on all the time, every time the engine is started. They are installed with computer control units or one or more thermostats.
Computer controlled electric fans are NOT doing the same amount of work as a mechanical or clutch fan. Therefore, they USE LESS ENERGY.
They DO NOT do the same amount of work as a mechanical or clutch fan OR they would USE THE SAME AMOUNT OF ENERGY!
It's strictly EFFICIENCY.
So, it's a "more bang for your buck" kind of thing.
Ok. History and physics lesson over. ;D ;D
If you can install an electric fan(s) and get it to do what the original mechanical or clutch fan was doing - which means get the equivalent cooling - using LESS energy, then you will free up HP for other things like zipping down the road.
If you install an electric fan(s) and they need to use the same amount of energy as the mechanical or clutch fan you're replacing - then you you will NOT free up HP.
I might point out that its possible to actually go BACKWARDS and use MORE by installing an electric fan(s). Something to keep in mind.
A vehicle needs less cooling capacity in northern lower temperature latitudes than it needs in southern hotter latitudes.
Replacing a mechanical fan or clutch fan in a location where the average temperature is 70 vs 90 will yield a higher return than the reverse. The electric fan that was installed in southern Texas for example, will have to function more often and work harder and use more energy than the same setup in northern Montana.
So, the real answer is 'It depends.'
There are lots of things that need to be taken into account when swapping to an electric fan setup from a mechanical or clutch fan. The primary thing being the electrical system - alternator and battery.
Electrical systems are not generally designed for overkill from the manufacturer. They're 'just good enough' + a tad. In other words, the electrical system is capable of handling the full load of all the accessories + the computer systems and lighting without discharging the battery. Not much more.
For example, the Sport alternator is a 85-90 amp alternator. All the accessories + lighting and computers will use up most of that. Based on my experiences, a pair of 80/100 H3s can be added without causing issues, but the added draw of electric fan(s) will start to discharge the battery. The electrical system is unable to keep up with the requirements of the accessories.
The obvious solution is to add a higher rated alternator and battery. But, remember what I said above, you don't get something for nothing. For simplicity's sake, we'll say this is linear and an 80 amp alternator requires 10 HP under full load. Twice that or 160 amps, will require 2x 10 HP, so 20 HP.
So, if the clutch fan requires 15 HP, now you're using 20 HP. Backwards.
Its a delicate balancing act because there are a lot of dependents. That's why I always say 'generally' or 'usually'. I can't guarantee you'll free up some HP and no one else can either. Even if you use the EXACT same parts they do.
Doing this particular conversion JUST for the sole purpose of freeing up a few ponies is probably not a good idea. Odds are good that you won't get out what you put in, let alone what you think you're going to get out. If you have other reasons like being able to turn off the fans for deep water crossings and that'll make the conversion a 'success' even if you end up with a wash as far as HP goes, then go for it.
Let me try and give kind of a brief idea ...
I put in the Contour fans with the SPAL controller on my big '97. I already had the battery for other reasons - more on that latter. INITIALLY, it did free up some HP. Enough for a reasonable increase in millage, so obviously something improved.
However, then I figured out that the config wasn't correct which required that I up the time the electric fan(s) operated. That decreased my gain. Mostly I got that where I wanted it.
Then I figured out that the alternator wasn't capable of running the fans AND the heater and headlights without discharging the battery. As I said above, you only get out what you put in and obviously wasn't putting in enough.
I already had an AGM battery - Optima - and switched to the Die Hard Platinum and upscaled. This is relevant because the charge time of an AGM battery is much lower than a standard wet cell. This is a Band-aid and I knew that - all it did was allow me to refil the battery quicker so the problem wasn't as bad - it did NOT fix the problem. You can't get more out then you put in. Period.
Then went in the new 3.5L. Which normally uses the same fan and radiator as a 3.0L so requiring EXTRA cooling wasn't a problem. However, apparently the 3.5L would sit further back if this was normally installed by the factory. Rather than re-engineer the mounts and supports, we installed it where the 3.0L normally sits. Which puts the front a bit further forwards - closer to the fan(s). This means the electric fans efficiency is decreased because of a lack of sufficient space between the rear of the fan and the engine. Not a big issue, but one that needs to be worked around. So, a custom aluminum radiator went in as part of the work-around.
Now I'm running a custom radiator, the Contour fans and SPAL controller with the 3.5L in the bay and a huge AGM battery. The next big thing - and this applies to ALL vehicles - was exhausting the heat.
This is something people overlook - you can not let the heat sit in the engine bay. Mechanical and clutch fans keep a minimum amount of air flowing through the engine bay ALL THE TIME. Even in the case of a clutch fan at 30 below zero at idle.
If you don't you end up with 'heat soak'. Heat soak is a bad, BAD, juju. Normally, just because it's 230 degrees in the engine bay, doesn't mean that EVERYTHING in the engine bay is at 230 degrees. However, if you don't exhaust that 230 degree air, it soon will be.
Besides decreasing the life expectancy of your electrical and electronics parts, it will also move the electronics out of the temperature range in which their designed to operate. WHICH will cause them to either not work at all or feed erroneous data to the computer(s). This will create a list of problems that aren't even really really have that you do not want to even think about.
This is where the catch is with electric fans. People do not install electric fan(s) so they can operate all the time the engine is running - hey, they just took OUT a fan that was doing just that, right? Well, there has to be air flow pretty much 100% of the time unless it's sub-zero degrees outside. That's the rub. You have to meet certain criteria no matter what type of fan is installed and if the requirement is that the fan run all the time to meet them, then that's the requirement and there's nothing you can do about it.
As it stands now, my controller turns on the 'primary' fan at 194 - below the actual opening temp of the thermostat - at 50%. At 216 the primary is at 100% and the secondary turns on at 100%. My primary fan IS NEVER OFF at operating temperature. The reason for this is that you CAN NOT let the engine bay heat soak and then AFTER the fact decide to turn on the fan(s). It is much harder and takes much more energy to cool everything back down than it does to keep everything at a reasonable operating temperature in the first place. Compounding the problem is the fact that now the computer is screwed up and unable to operate the engine at peak efficiency - effectively blowing energy (HP) out the tail pipe.
So, what's the point of having electric fans then? Well, in my case, it takes a little less energy to power an electric fan at 60%, 90% of the time my vehicle is running than a clutch fan 100% of the time the vehicle is running. Also, the fan isn't ON until the engine warms up which means faster warm up time - nice in the winter - which cuts done on fuel usage and emissions in the warm up phase.
On a normal Sport it may not be necessary to run more than 50-60% on the highway - or even at all. Normal air flow through the system while the vehicle is moving forward may be sufficient to keep everything cool in which case you'd recover ALL the HP a clutch or mechanical fan would normally be using.
So, at the end of the day, while I do free up a couple HP - most of the time - it's not what most people would expect to get from a conversion. During the day when it's hot out and the fan needs to run at a higher speed I get something out of it. However, during the night with the lights on and it's hot out my battery discharges - which means that every HP I saved during the previous day, now is used to recharge the battery from the previous night's driving.
That's why really the correct answer is 'your millage may vary'.
I apologize again for the length but hopefully this clears things up a little.
Edward
Unlike the HP use of a strict mechanical fan, HP use isn't linear. So, instead of 1:1 irrespective of the engine RPM, you can have 1:.5, 1:.1, 1:.9 or 1:1 at any RPM, depending on what the temperature is.
