Mechanical vs Electric fans question

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MrJLR

Built, not bought
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Why has almost every automotive manufacturer gone to electric fans?
Is it more efficient? Do they cool better? Are they cheaper. ..more dependable?

I'd like to hear your opinions on this.....
I'm considering going to electric fans...by the time I buy a good fan, and a shroud it would be a wash money wise.
I don't have a cooling problem but I have a dangerous flex fan and no shroud.


Jeff
 
Since the engines are sideways, there is no room for a belt driven fan. Plus, a belt driven fan cuts down on efficiency, since it takes direct power from the engine to drive it.

I still prefer a belt driven fan.
 
My car is like yours with a 273 out .040. I added a clutch fan, built my own shroud and had the radiator recored to a 3 row by 7/16". With my mechanical temperature gauge I can watch the stat open at 190 and close at 180. I would not add the problems of electric fans but that's just me.
 
Clutch fans and a shroud are probably your best bet. I got about 3 mpg better after adding a clutch fan to my 318, still need a shroud for better cooling efficiency, but i'm not running hot either. In my 350 s10 I run 2 electric pushers and a belt driven flex fan, would rather have a clutch fan but no room.
 
If you go with an eletric fan think about this ur using mechanical energy to make electrical energy back to mechanical energy
 
Measure the outside diameter and compare to what is advertised for the clutch fan. Depth wise, I took off the factory spacer for the stock fixed fan and the clutch fan had plenty of clearance both to the belts as well as the radiator
 
If you go with an eletric fan think about this ur using mechanical energy to make electrical energy back to mechanical energy
True, but the electric fan is only running when the radiator is hot, not all the time. Plus it can run when the engine is off, if you want.
 
other than that, how's the car running??? performing??? Does it meet your expectations? Exceed your expectations? or needs improvement......?
 
LOL.....just throw money at it huh?!

I know I don't have the correct radiator for 1968....gotta figure out what I have.....



Jeff

Heck yeah! Ain't that what everybody does these days? LOL
 
other than that, how's the car running??? performing??? Does it meet your expectations? Exceed your expectations? or needs improvement......?

It runs great!
I need to get the exhaust done still and I wish I would have got a higher stall torque converter....
But it's also possible that it'll improve when I get the kickdown (throttle pressure) set up properly...

It burns the tires from a dead stop but not very long....I think there's more performance hiding in there still!

Overall - I'm loving it!

Jeff
 
I've run a thermostatically controlled puller electric fan in a 64 Barracuda, no mechanical fan. Worked fine and was great for quick warm ups in South Dakota winters. However you can not get more bulletproof than a mechanical fan. I've had electrics go out, Jeep Cherokee, and clutch fans fail also. Worse is a water pump. Not much stress on a water pump without the fan. What is a dangerous flex fan?
 
I've run a thermostatically controlled puller electric fan in a 64 Barracuda, no mechanical fan. Worked fine and was great for quick warm ups in South Dakota winters. However you can not get more bulletproof than a mechanical fan. I've had electrics go out, Jeep Cherokee, and clutch fans fail also. Worse is a water pump. Not much stress on a water pump without the fan. What is a dangerous flex fan?
Dangerous as in razor sharp blades spinning around and no shroud. Not to mention they have been known to throw a blade.....

Jeff
 
RRR already posted one of the big reasons that electric fans started to appear, transverse engines. But now you can pretty much find them on everything, even some semi's are running them now. The reason for this isn't cost, at least, not the cost of the fan system. A mechanical fan doesn't need all the electrical components and systems that an electric fan does, bolt it on and go. With an electric fan set up you need relays, motors, switches, feet of wiring, a separate circuit, etc. But what you gain in all of that is precise temperature control, and that's why they're used on most new cars. The ECU controls when the fans are running, so, you can keep the engine at it's ideal operating temperature more often and more reliably. And that's efficiency, and that's gas mileage.

As far as efficiency, it's not just the conversion of energy you have to consider. Yes, an electric fan requires energy to be converted from mechanical to electrical and back to mechanical, and there's loss there. But, every second a mechanical fan is spinning that an electric one isn't is lost energy. If you've got a thermostatic fluid coupler on your mechanical fan that won't be a huge amount of time, but it will still spin more because of the way those operate, it takes time for the temperature change to register. And then there's the efficiency of the fan blade itself. A mechanical fan blade has to work over a wide range of RPM's, anywhere from idle to full throttle. Now, if you have a thermostatic fluid coupler it won't always be spinning 1:1, but it will still operate over a wide range of rpm's. And over that range of rpm's the fan blade has it's own range of efficiency and a wide range of CFM output. A fan blade designed to spin at 3k rpm will be most efficient at that speed. Sure, it will still move air at 5k rpm and at 1k rpm, but it's not the most efficient there, you're losing energy. An electric fan has a significant advantage there, it always spins at the same speed. So, the fan can be designed for peak efficiency at that speed and it will always be there. Unless of course you have a 2 speed electric fan, but in that case the fan is still designed for the lower speed and the high speed trades peak efficiency for CFM knowing that the high speed isn't where the fan spends most of it's time.

With an electric fan the better the controller the better the fan will work. New cars are controlled by the ECU, so there's a tremendous amount of control there, it doesn't just have to be a temperature range like the fans come on at 200* and turn off at 205*, the ECU can turn them on and off based on the temperature of the engine, engine RPM, speed of the vehicle, output of the oxygen sensor, you name it, they can be as complicated as you want. And that's where the retro-fit electric fans usually have their problems and why people say they don't work, they hook an improperly sized fan to a cheap generic temperature switch and are surprised when the result doesn't cool well. Same for reliability. I use an OE electric fan set up from a Ford Contour. It was designed and tested by Ford for use on a car what was designed to last hundreds of thousands of miles. Aftermarket fans, even the high end ones, don't necessarily get that kind of testing.

A good electric fan system is going to cost more than a thermostatic fan clutch, mechanical fan and shroud. Possibly a lot more depending on how you do it. You'll need a fan that can push a few thousand CFM, at least one relay, a good fan controller (not just a cheapo temp switch sender), a bunch of heavy gauge wire and probably even a higher output alternator to power a fan that pushes enough CFM. With all of that done properly, the electric fan should be more efficient and do a better job of keeping the engine within it's operational temperature range. I know mine does. My "new" '74 Duster- or why I need a project like a hole in the head

But there's a lot of work that has to be done to make that happen, and since none of that is on the car already it's probably better to spend the money on a good thermostatic fan coupler and a shroud. It will look stock and should be up to the task of cooling all but the really high horsepower cars.
 
I've got a clutch fan I need to install on my setup. I used the hayden 2765. If you look it up it'll give you detailed measurements on it. My car runs cold as is. Hoping the clutch fan will help put some heat into the engine.

As for flex fans? They are all dangerous. Known to cleave fingers off. Or explode and put bits in your chest or worse.
 
RRR already posted one of the big reasons that electric fans started to appear, transverse engines. But now you can pretty much find them on everything, even some semi's are running them now. The reason for this isn't cost, at least, not the cost of the fan system. A mechanical fan doesn't need all the electrical components and systems that an electric fan does, bolt it on and go. With an electric fan set up you need relays, motors, switches, feet of wiring, a separate circuit, etc. But what you gain in all of that is precise temperature control, and that's why they're used on most new cars. The ECU controls when the fans are running, so, you can keep the engine at it's ideal operating temperature more often and more reliably. And that's efficiency, and that's gas mileage.

As far as efficiency, it's not just the conversion of energy you have to consider. Yes, an electric fan requires energy to be converted from mechanical to electrical and back to mechanical, and there's loss there. But, every second a mechanical fan is spinning that an electric one isn't is lost energy. If you've got a thermostatic fluid coupler on your mechanical fan that won't be a huge amount of time, but it will still spin more because of the way those operate, it takes time for the temperature change to register. And then there's the efficiency of the fan blade itself. A mechanical fan blade has to work over a wide range of RPM's, anywhere from idle to full throttle. Now, if you have a thermostatic fluid coupler it won't always be spinning 1:1, but it will still operate over a wide range of rpm's. And over that range of rpm's the fan blade has it's own range of efficiency and a wide range of CFM output. A fan blade designed to spin at 3k rpm will be most efficient at that speed. Sure, it will still move air at 5k rpm and at 1k rpm, but it's not the most efficient there, you're losing energy. An electric fan has a significant advantage there, it always spins at the same speed. So, the fan can be designed for peak efficiency at that speed and it will always be there. Unless of course you have a 2 speed electric fan, but in that case the fan is still designed for the lower speed and the high speed trades peak efficiency for CFM knowing that the high speed isn't where the fan spends most of it's time.

With an electric fan the better the controller the better the fan will work. New cars are controlled by the ECU, so there's a tremendous amount of control there, it doesn't just have to be a temperature range like the fans come on at 200* and turn off at 205*, the ECU can turn them on and off based on the temperature of the engine, engine RPM, speed of the vehicle, output of the oxygen sensor, you name it, they can be as complicated as you want. And that's where the retro-fit electric fans usually have their problems and why people say they don't work, they hook an improperly sized fan to a cheap generic temperature switch and are surprised when the result doesn't cool well. Same for reliability. I use an OE electric fan set up from a Ford Contour. It was designed and tested by Ford for use on a car what was designed to last hundreds of thousands of miles. Aftermarket fans, even the high end ones, don't necessarily get that kind of testing.

A good electric fan system is going to cost more than a thermostatic fan clutch, mechanical fan and shroud. Possibly a lot more depending on how you do it. You'll need a fan that can push a few thousand CFM, at least one relay, a good fan controller (not just a cheapo temp switch sender), a bunch of heavy gauge wire and probably even a higher output alternator to power a fan that pushes enough CFM. With all of that done properly, the electric fan should be more efficient and do a better job of keeping the engine within it's operational temperature range. I know mine does. My "new" '74 Duster- or why I need a project like a hole in the head

But there's a lot of work that has to be done to make that happen, and since none of that is on the car already it's probably better to spend the money on a good thermostatic fan coupler and a shroud. It will look stock and should be up to the task of cooling all but the really high horsepower cars.

Excellent write up...makes a lot of sense - thank you!

When I'm ready with some coin, I'll post up pictures of my not-original radiator and we if we can't identify it and get me the right fan and shroud....sounds like the way to go!

Thanks!

Jeff
 
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