Plumcrazyfreak
Well-Known Member
Please respond with Pro's & Con's. Advantages & Disadvantages.
Mechanical Fan VS Electric Fan
- Thread starter Plumcrazyfreak
- Start date
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Mech fan, cheap, plentiful and when equipped with a clutch, effective.
Elect fan, can be expensive if you go over the top with Daimler fans and custom shrouds and stuff. Some electrical system knowledge required. But when its done works excellent, plus you'll get back the h.p. that the mechanical fan took away and get a boost in MPG to boot.
Elect fan, can be expensive if you go over the top with Daimler fans and custom shrouds and stuff. Some electrical system knowledge required. But when its done works excellent, plus you'll get back the h.p. that the mechanical fan took away and get a boost in MPG to boot.
inkjunkie
Well-Known Member
Both should be used with a shroud. Several companies can fab you up an aluminum shroud if you were to use electric ones. Mech. ones, very very rarely, will come apart. Lectric ones will die sooner or later, it is after all, just an electric motor......
I have never been able to get my brain around this. The relationship between mass and power being linear. If you move X mass of air with a mechanical fan, and X mass with an electromechanical fan. the power required to move the mass (rotating force to rotate the fan blades) should be identical. Belt turning fan or belt turning an alternator. Actually the electric fan should be a little less efficient, with losses in the alternator and resistance in the low voltage wiring, 2 sets of bearings vs. 1 etc... Some one help me out here.
I got 1 mpg and done nothing but change from a mechanical to electrical on a small block Duster, and 1-2on a 87 3/4 ton pickup.
1968FormulaS340
Well-Known Member
Well...... If you have the electric fan on a thermostatically controlled switch, that's where this savings really comes into play.
That's my guess anyway.
A lot of electical fans put a big strain on electrical systems that were not engineered/built for them.
very true! that's why I done the madd electrical thingiemajigg!!! You notice you can't even find a late model anything with a viscous coupled fan...
Plumcrazyfreak
Well-Known Member
Is the cooling potential similar ? What kinda Hp gain can be seen ?
Mr.Ed
Swollen Member
Mass and power relationship may be linear but many other factors are not. An electric fan spins at a constant speed independent of engine RPM whereas a mechanical fan has to turn X revolutions per RPM. The mass of the fan, clutch, belt and pulley have to be accelerated with the engine which is what robs HP. If your cooling system is sized correctly, most of the time you don't need a fan if you're going over 30 mph and even at a idle, a thermostatically controlled electric fan will operate only when it's needed.
Sometimes I can't help being the antagonist, in order to bring some intelligent debate? :hello1:
If mechanical fan clutches were as efficient as temperature controls are things would be different. During periods of max cooling requirement a fully locked up mechanical fan is hard to beat. Cruising over 30 mph I do agree that mechanical fans don't completely unlock causing some loss in efficiency.
Now a clutch driven mechanical fan with a telemetry ring for control Hmm????? :happy3:
If mechanical fan clutches were as efficient as temperature controls are things would be different. During periods of max cooling requirement a fully locked up mechanical fan is hard to beat. Cruising over 30 mph I do agree that mechanical fans don't completely unlock causing some loss in efficiency.
Now a clutch driven mechanical fan with a telemetry ring for control Hmm????? :happy3:
livininharrow
Active Member
anything driven from your crankshaft is a power robber. go with an electric fan and don't be cheap. go with an electric water pump as well. just make sure you have a big enough alternator. this is not rocket science here.
cudaspaz
Well-Known Member
I have both mechanical and electric back up pusher fan for when I'm at red lights on very hot days or stop and go traffic.
The electric back up is well worth it when I need it.
The electric back up is well worth it when I need it.
Rice Nuker
Let the Coal Roll!
I concur on the power relationship and power transition. You turn your elec fan with your alternator which robs power from your crank. It all is just transition of energy and there is loss in transition so the less transition the better.
Here is an additional item. How much cfm you think a big *** electrical fan pushes (pulls)? Probably 3000. Eating 50 - 60 amps. How much horse power does it take to make 60 amps in your alternator? What am I nerd scientist? I don't know. My guess is 10.
When a thermostatically controlled clutch fan is active it is moving easily 5000 - 8000 cfm depending on the vehicle (fan blade / shroud). Most after-market electric fans push about 2000 or so cfm. It varies based on price mostly. Just look at the cfm of elec fans on summit. Then look up the cfm of thermo-clutch fans.
Also, v6 factory electric fans push (pull) more cfm than most any after-market elec fan. Like on a 93 taurus.
http://www.rockauto.com/catalog/moreinfo.php?pk=688728
2 or 3 speeds with quite amazing cfm and cheap as hell compared to aftermarket. Get one at the junk yard and mod it.
A good working thermostatically controlled clutch fan with a modern designed fan blade and a fitting shroud is the best for a street v8. I have never had an over heating issue running a stock thermo-clutch fan with or with out a shroud unless I had a hole in my radiator and the fluid leaked out or my radiator was completely clogged with 25 years of rust. Ive lived in the south most my life and raced many days in 100 degree weather. Nice thing is a thermo-clutch will handle the temp for you and use HP only when cooling is needed. Most my thermo-clutch fans were dis-engaged to the extent that you could stop the blade with a big stick while the engine was running. I doubt it was consuming any HP (this is during idle). The down side is it may decide to engage while you are racing and rob you of some horses.
I constantly hear people having overheating issues while using aftermarket electric fan(s) and they do every other thing, rather than just put a clutch fan on it most the time. I have also heard several people solving their overheating issues by dumping the aftermarket elec fan (s) for a clutch fan with a shroud.
Electric fans are probably good for remote radiators, space constraints, and drag race apps. There is no other practical reason to run one that I can come up with.
Good quality thermo-clutch fan with proper shroud.
1968FormulaS340
Well-Known Member
For a track car....... Sure. But not the best choice for a dedicated street car.
Howard1784
Well-Known Member
I had heat probs. all the time. Went to Chevy 19X22 alum. custom shroud and dual fans pulling 4500 cfm's. Upgraded to 80 amp Powermaster to pick up the slack. As stated above, this was pricey. $500 for the fan shroud assembly and @200 for the radiator.
Mr.Ed
Swollen Member
Where do you get 50 or 60 amps from? 25 or 30 amps is more realistic. Also where does it say you need 8,000 CFM? If your radiator is properly sized for the engine and it's HP level you shouldn't need that much air. Of course there are variables such as rate of coolant flow and ambient temp.
How much does your entire clutch fan assy. weigh? Remember, that's rotating weight. That mass and inertia have to be overcome every time the engine RPM changes. That's what robs HP even in freewheeling mode. Even if the fan itself is negligible (which it's not) the pulley, belt and clutch still turn at engine speed.
That's because the radiator's cooling capacity is too small for the HP they're making and they need to pull more air through the radiator.
The only reason for having a propeller on the front of your engine is if you plan on leaving the ground, but then you'd need a bigger propeller. Engine driven fans are cheap and simple. Other than that, electric is the way to go.
SRT_DSTRHOLC
Well-Known Member
Champion fans and rad. no shroud less than 300 and runs cooler than 190
inkjunkie
Well-Known Member
Sir, I am trying to edjumucate meself, what is a telemetry ring and where might I locate one? Is it in the aisle with the spinfaster muffler bearings?? This stuff is SO confusing....:banghead::banghead::banghead:
inkjunkie
Well-Known Member
Please take this for what it is worth, which aint much. I have a 02 Chebby with a Duramax in it. I have towed some with it. Climbed up I-17 in AZ (115* air temp) with 10k pounds on the trailer and in the bed of my truck, which has the OEM clutch fan on it with a thermo clutch on it. You could hear the clutch locking/unlocking, even going down hill at 85-90 mph. Under normal conditions a fan may not be necessary at freeway speeds, but it does not always apply. Last trip home from AZ was unloaded and the fan still cycled. On the other hand, our Fairlane, which has a cooling issue (no shroud), will run with the t-stat closed while going down a grade, even in 110* heat. The point is...got me, I just felt like rambling......
Rice Nuker
Let the Coal Roll!
"Where do you get 50 or 60 amps from? 25 or 30 amps is more realistic. Also where does it say you need 8,000 CFM? If your radiator is properly sized for the engine and it's HP level you shouldn't need that much air. Of course there are variables such as rate of coolant flow and ambient temp."
First off, I think of the "street" all the time. Not sure what Plumcrazy's application is. I like to design systems that will last 50 - 100 K as I like to drive my rig anywhere w/o issue at any time of year for miles and miles, for ever. Of course a person will have issues, but I like to minimize them to the minimum.
My last big build was reliable to 50 k with no cooling issues, it was a 462 cube olds in an ss monte carlo with 10.25 to 1 and tall gears. Factory used clean radiator, used Clutch fan from the junk yard, no shroud. Eventually I blew the trans off the motor and into a million pieces and took a chunk out of the engine block at 150 on a back road in the country at 1 am, because of a U joint failure (I suppose). But it stayed cool. This was a car with .229 gears used for long road hauls out in the hills of the South.
I have always run a thermo clutch and they never let me down. I have seen a hand full of factory and aftermarket elec fans let people down and that sucks big time. Overheated and stranded because a fuse blew, a fan motor seized up, fan motor started smoking, thermo controller went out, relay melted.
Alot of compromise can be made when you dont plan to drive 1000 - 2000 miles in a week across route 66, up thru colorado and down thru california in the middle of summer with the AC blasting, hauling *** repeatedly for years.
Well, a pair of elec fans or one big one that will let you run up a mountain in 100 degree heat at 75 - 90 mph with a trunk full of beer and a car full of friends with the A/C on will eat serious amps. Those amperage numbers I pulled out of my butt.
I am just estimating on a factory cooling system which is designed to properly cool with the AC on and in any condition on a V8 VS. most aftermarket electrical fans where the cooling is quite relative to the price.
The factory designs their systems to be reliable for 100k. Its hard to beat that.
If a person can get by with an economical elec cooling fan setup then great. I would not do it on the street because I would not want the electrical draw on my system, relays and alternator. Additional complexity, additional failure points and expense of what would be required to have a guaranteed more than adequate haus of an elec fan setup (such as the one Howard 1784 posted).
In other words that fan setup of Howard's looks like something that would be a great replacement for a clutch fan. How much amperage does your setup use Howard? I mean that thing is awesome.
This is why you find big *** heavy duty electric fans or a thermo clutch on big autos. I was not saying you need 8000 cfm but rather that large thermo fans pull near that, such as on an f250. Old v8 Car clutch fans pull about 5000.
Here is a clutch fan scenerio : 40 - 60 bucks for new clutch, fan blade at junk yard, blasted and painted 20 - 40 bucks, use factory shroud. My car had a clutch fan and shroud on it (360) so, I reckon my fan situation will cost near nil.
Were talkin a done deal which will last near 25 yrs w/o fail and has zero additional requirements to maintain functionality. So, 100 dollars investment that fits w/o modification for a done deal. Simple, economical, reliable and uses minimal HP.
Now rotating mass. The fan is clutched by fluid coupling so its rotational inertia is not what you would perceive nearly as much as the drag in hp which is really only active during cooling necessity (similar to a thermo elec fan). The clutch weighs 5 pounds? I agree that if you are saving every last gram of rotating mass and HP draw, a clutch fan would be slightly more draw.
If I were to run an elec fan on the street, and by on the street I mean driving around any time of year to any place in the country w/o any cooling issue, it would have to be guaranteed to be a couple notches above good enough and last 10 years minimum. That sweet fan system on Howard's post looks like it would do the job well.
Here is a nice summary of a thermo clutch fan vs elec fan. The comparison is good, some of the rx7 info is not applicable.
http://www.aaroncake.net/RX-7/efanmyth.htm
First off, I think of the "street" all the time. Not sure what Plumcrazy's application is. I like to design systems that will last 50 - 100 K as I like to drive my rig anywhere w/o issue at any time of year for miles and miles, for ever. Of course a person will have issues, but I like to minimize them to the minimum.
My last big build was reliable to 50 k with no cooling issues, it was a 462 cube olds in an ss monte carlo with 10.25 to 1 and tall gears. Factory used clean radiator, used Clutch fan from the junk yard, no shroud. Eventually I blew the trans off the motor and into a million pieces and took a chunk out of the engine block at 150 on a back road in the country at 1 am, because of a U joint failure (I suppose). But it stayed cool. This was a car with .229 gears used for long road hauls out in the hills of the South.
I have always run a thermo clutch and they never let me down. I have seen a hand full of factory and aftermarket elec fans let people down and that sucks big time. Overheated and stranded because a fuse blew, a fan motor seized up, fan motor started smoking, thermo controller went out, relay melted.
Alot of compromise can be made when you dont plan to drive 1000 - 2000 miles in a week across route 66, up thru colorado and down thru california in the middle of summer with the AC blasting, hauling *** repeatedly for years.
Well, a pair of elec fans or one big one that will let you run up a mountain in 100 degree heat at 75 - 90 mph with a trunk full of beer and a car full of friends with the A/C on will eat serious amps. Those amperage numbers I pulled out of my butt.
I am just estimating on a factory cooling system which is designed to properly cool with the AC on and in any condition on a V8 VS. most aftermarket electrical fans where the cooling is quite relative to the price.
The factory designs their systems to be reliable for 100k. Its hard to beat that.
If a person can get by with an economical elec cooling fan setup then great. I would not do it on the street because I would not want the electrical draw on my system, relays and alternator. Additional complexity, additional failure points and expense of what would be required to have a guaranteed more than adequate haus of an elec fan setup (such as the one Howard 1784 posted).
In other words that fan setup of Howard's looks like something that would be a great replacement for a clutch fan. How much amperage does your setup use Howard? I mean that thing is awesome.
This is why you find big *** heavy duty electric fans or a thermo clutch on big autos. I was not saying you need 8000 cfm but rather that large thermo fans pull near that, such as on an f250. Old v8 Car clutch fans pull about 5000.
Here is a clutch fan scenerio : 40 - 60 bucks for new clutch, fan blade at junk yard, blasted and painted 20 - 40 bucks, use factory shroud. My car had a clutch fan and shroud on it (360) so, I reckon my fan situation will cost near nil.
Were talkin a done deal which will last near 25 yrs w/o fail and has zero additional requirements to maintain functionality. So, 100 dollars investment that fits w/o modification for a done deal. Simple, economical, reliable and uses minimal HP.
Now rotating mass. The fan is clutched by fluid coupling so its rotational inertia is not what you would perceive nearly as much as the drag in hp which is really only active during cooling necessity (similar to a thermo elec fan). The clutch weighs 5 pounds? I agree that if you are saving every last gram of rotating mass and HP draw, a clutch fan would be slightly more draw.
If I were to run an elec fan on the street, and by on the street I mean driving around any time of year to any place in the country w/o any cooling issue, it would have to be guaranteed to be a couple notches above good enough and last 10 years minimum. That sweet fan system on Howard's post looks like it would do the job well.
Here is a nice summary of a thermo clutch fan vs elec fan. The comparison is good, some of the rx7 info is not applicable.
http://www.aaroncake.net/RX-7/efanmyth.htm
Rice Nuker
Let the Coal Roll!
This is an electronically controlled fan clutch for a v8
http://www.monsterautoparts.com/che...let_trailblazer_fan_clutch_radiator_blade.htm
Top item on page.
Mr.Ed
Swollen Member
Nuker, you and I have the same philosophy... build it for 100k miles, drive anywhere at any time with anvil-like reliability. We just go about it with different methods. On my build, I'm using Spal dual electric fans with a fan controller set up for 2-speed operation to minimize amperage draw and noise. http://www.forabodiesonly.com/mopar/showthread.php?p=1057036#post1057036
Although for reliablility, I agree that a mechanical fan/clutch assy. is hard to beat but I think electronic equipment is pretty reliable these days for the most part as long as you use a quality manufacturer. Almost all new cars use an electric setup these days and you know the manufacturers don't do something unless there's some benefit to it (although the benefit is sometimes due to packaging issues.)
Hey how about a thermostatically controlled hydraulically operated fan?
Although for reliablility, I agree that a mechanical fan/clutch assy. is hard to beat but I think electronic equipment is pretty reliable these days for the most part as long as you use a quality manufacturer. Almost all new cars use an electric setup these days and you know the manufacturers don't do something unless there's some benefit to it (although the benefit is sometimes due to packaging issues.)
Hey how about a thermostatically controlled hydraulically operated fan?
Rice Nuker
Let the Coal Roll!
"Almost all new cars use an electric setup these days and you know the manufacturers don't do something unless there's some benefit to it (although the benefit is sometimes due to packaging issues.)"
Seems like there should be some new cars you could get an elec fan setup off that would be pretty powerful and factory reliable and apparently fairly economical if a person was into the electric fans. I wonder if they would be sufficiently powerful enough for a big block..
http://www.am-autoparts.com/Chrysler/300C/RadiatorFanAssemblies/AM-69373408/365001.html
http://www.am-autoparts.com/2005/Mercury/GrandMarquis/RadiatorFanAssemblies/AM-32297836/215353.html
"http://www.forabodiesonly.com/mopar/...36#post1057036"
Very precise and nice, Mr. Ed.
"Hey how about a thermostatically controlled hydraulically operated fan?"
Such as a hydraulic pump and a radiator fan run by a hydraulic motor? Think those are on some big diesel generators or some such. I believe I saw one when I was a kid. Sounds quite cumbersome for a car app I speculate
.
Here is one on a pusher!
http://www.eaton.com/ecm/groups/public/@pub/@eaton/@hyd/documents/content/ct_154549.pdf
:burnout:
Seems like there should be some new cars you could get an elec fan setup off that would be pretty powerful and factory reliable and apparently fairly economical if a person was into the electric fans. I wonder if they would be sufficiently powerful enough for a big block..
http://www.am-autoparts.com/Chrysler/300C/RadiatorFanAssemblies/AM-69373408/365001.html
http://www.am-autoparts.com/2005/Mercury/GrandMarquis/RadiatorFanAssemblies/AM-32297836/215353.html
"http://www.forabodiesonly.com/mopar/...36#post1057036"
Very precise and nice, Mr. Ed.
"Hey how about a thermostatically controlled hydraulically operated fan?"
Such as a hydraulic pump and a radiator fan run by a hydraulic motor? Think those are on some big diesel generators or some such. I believe I saw one when I was a kid. Sounds quite cumbersome for a car app I speculate
. Here is one on a pusher!
http://www.eaton.com/ecm/groups/public/@pub/@eaton/@hyd/documents/content/ct_154549.pdf
:burnout:
Plumcrazyfreak
Well-Known Member
A new twist to this..........Thermostat or no thermostat ?
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