Electric vs mechanical cooling fan
#31
07-23-2015, 09:05 AM
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I like electric cooling fans due to the ability to do more with them in regards to control and setup. A mechanical fan (with or without a clutch) is very straight forward and has its advantages but the electric fan has its own advantages as well.
Climate plays a big part. Do you only drive in hot weather, do you need XX amount of CFM to keep cool, can your electrical system supply the demanded current to run the fan(s).
If you want to run a mechanical fan and add a electric pusher fan to the front of the radiator it is very easy and you can probably get away without upgrading your charging system. Mount the fan, add a relay kit/control and you are done.
Climate plays a big part. Do you only drive in hot weather, do you need XX amount of CFM to keep cool, can your electrical system supply the demanded current to run the fan(s).
If you want to run a mechanical fan and add a electric pusher fan to the front of the radiator it is very easy and you can probably get away without upgrading your charging system. Mount the fan, add a relay kit/control and you are done.
#32
07-23-2015, 05:57 PM
You had to use the word 'undeniable'... 
The electric fan doesn't "eliminate" a drag on the engine, it creates its own drag via the alternator. That is undeniable. You're merely trading simple mechanical drag for electrically induced mechanical drag. Sometimes, there is an advantage to doing this...sometimes not.
What is arguable and debatable is efficiency of the two...but there's a lot of missing information to make a gnat's butt type of comparison. As everyone said, the difference is not significant most of the time and it will come down to packaging, preference, and what you've got lying around.
It absolutely addresses the OP post - he was getting pros/cons and the WHY behind the opinions, which is often as important, if not more so, than simply the opinion. When people say things like, "they allow for a hp increase as there is no drag reduction due to turning the fan" or "They belt driven is on, period", that needs to be addressed - nobody wins when incomplete information is provided.
The OP asked what is best for keeping it cool. There is no 'best' without defining the parameters and constraints. If money is no object, Then we can all probably build a whiz-bang, high-end, custom-tailored package for him. If he wants to keep his electrical system as-is and he already has a functioning mechanical fan that is doing the job, perhaps a simple fan shroud would be 'best' to optimize what he has with the least amount of financial outlay.
Electric vs mechanical fans can get into some pretty arcane nuances, I admit and we've seen on this thread. But as I've said several times in this thread, it's all but impossible to put an apples-to-apples comparison without knowing the CFM of the OEM fan being removed. Most modern mechanical fans will move far more air than electric fans could ever hope to. An advantage often exists for the electric an at idle and very slow speeds. Above about 30 mph, neither one makes a difference. But there's a reason all the severe duty police packages have huge, aggressive mechanical fans with big thermal clutches on them...
I don't have a preference, really. I slightly favor a well thought out mechanical system simply for reliability, but honestly, it doesn't matter to me - packaging is more important most of the time - particularly with an engine swap. If you're talking original, there is no discussion...there is only one correct original for any application. If you want "best", then you have to define a lot of parameters.
I find these discussions to be good. Everyone comes away with some new tidbits of info...even the "experts". Learning is good for the hobby, good for the spirit, and keeps the mind flexible.
The electric fan doesn't "eliminate" a drag on the engine, it creates its own drag via the alternator. That is undeniable. You're merely trading simple mechanical drag for electrically induced mechanical drag. Sometimes, there is an advantage to doing this...sometimes not.
What is arguable and debatable is efficiency of the two...but there's a lot of missing information to make a gnat's butt type of comparison. As everyone said, the difference is not significant most of the time and it will come down to packaging, preference, and what you've got lying around.
It absolutely addresses the OP post - he was getting pros/cons and the WHY behind the opinions, which is often as important, if not more so, than simply the opinion. When people say things like, "they allow for a hp increase as there is no drag reduction due to turning the fan" or "They belt driven is on, period", that needs to be addressed - nobody wins when incomplete information is provided.
The OP asked what is best for keeping it cool. There is no 'best' without defining the parameters and constraints. If money is no object, Then we can all probably build a whiz-bang, high-end, custom-tailored package for him. If he wants to keep his electrical system as-is and he already has a functioning mechanical fan that is doing the job, perhaps a simple fan shroud would be 'best' to optimize what he has with the least amount of financial outlay.
Electric vs mechanical fans can get into some pretty arcane nuances, I admit and we've seen on this thread. But as I've said several times in this thread, it's all but impossible to put an apples-to-apples comparison without knowing the CFM of the OEM fan being removed. Most modern mechanical fans will move far more air than electric fans could ever hope to. An advantage often exists for the electric an at idle and very slow speeds. Above about 30 mph, neither one makes a difference. But there's a reason all the severe duty police packages have huge, aggressive mechanical fans with big thermal clutches on them...
I don't have a preference, really. I slightly favor a well thought out mechanical system simply for reliability, but honestly, it doesn't matter to me - packaging is more important most of the time - particularly with an engine swap. If you're talking original, there is no discussion...there is only one correct original for any application. If you want "best", then you have to define a lot of parameters.
I find these discussions to be good. Everyone comes away with some new tidbits of info...even the "experts". Learning is good for the hobby, good for the spirit, and keeps the mind flexible.
I agree. I enjoy the back and forth and as usual, have learned a few things here. But, please go back and look at my referred post. I did acknowledge the drag on the alternator.
Having driven several police packages, I have seen both electric and mechanical. I can honestly say I never noticed a huge difference between the two.
The paragraph below came for a Hot Rod article. I will supply a link.
The most common musclecar cooling-system problems concern low-speed cooling, most often attributed to low airflow through the radiator. Assuming the radiator is sized properly and there is decent coolant speed, then increasing airflow at low vehicle speeds should remove sufficient heat from the radiator to keep the engine at a manageable temperature. Engine-driven fans can move a tremendous amount of air but are also compromised by slow engine speed at idle while delivering sufficient airflow at higher engine speeds. Electric fans have become popular with the OEMs because they can move enough air at low speeds to keep the engine cool, relying on vehicle speed to push air through the radiator at highway speed. This reduces parasitic horsepower losses at highway speeds by eliminating the engine-driven fan. While this may seem trivial, dyno testing in the May '00 issue of Car Craft resulted in losses of 35 hp at peak horsepower from a simple one-piece, plastic, engine-driven fan. Clutch fans lost between 8 and 19 hp depending upon the clutch model, while a Flex-a-lite Black Magic electric fan driven by the alternator cost 1 hp. All these numbers were generated using a 496hp small-block Chevy at 6,300 rpm.
Read more: How to Design And Build A High-Performance Cooling System - How To - Car Craft Magazine
Granted, the engine in the article is not at all similar to a stock or near stock F-1. But the information is relative.
#33
07-23-2015, 06:49 PM
Fleet Owner
Fan HP is a cubic function of RPM, if you want to back those numbers down to reality.
#35
07-24-2015, 05:19 AM
#36
07-24-2015, 05:27 AM
LOL, not many flatheads turning 6300, for sure. I have to wonder if the 1 HP electric fan was really able to fully cool a 500 HP engine, if so it is one miracle of a fan. It does have a nice shroud.
Fan HP is a cubic function of RPM, if you want to back those numbers down to reality.
Fan HP is a cubic function of RPM, if you want to back those numbers down to reality.
It's not a 1 hp fan. The fan creates a 1hp loss on the engine. I don't think they mentioned the hp rating of the fan itself.
#37
07-27-2015, 03:16 PM
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Cooling systems have evolved since the muscle car days. To use modern electric fans compared to older mechanical systems is not quite an apples to apples comparison.
One of the primary reasons the electric fans "free up HP" is because they do not move nearly as much air as a mechanical fan at higher RPM. However, they make up for it at idle and low speed. But this is not the same thing as saying they are more efficient, because they are not. However, this is why the modern mechanical fans, particularly in the severe duty packages, are very aggressive, multi-blade mechanical fans with a large thermal clutch. Even a direct-drive flex fan will usually beat out a stock muscle car fan, few of which had a clutch. So the Car-Craft article, while correct in that application, is not doing an apples to apples comparison.
There's a curve based on RPM and CFM that will show you where a given mechanical fan will being to flow more air than a given electric fan. If your vehicle operates in this area of the curve, a mechanical is a much better option. Most of our street driven cars/trucks don't fall in this area, or if they do, very far into it.
There are a few applications where mechanical fans would be advantageous - high RPM, low speed - like tractors, rock crawlers, mud trucks, etc.
As the article points out, the simple mechanical fan is the "worst" when looking at HP loss and the clutch fan is next best. What they imply, but don't actually say, is that 1hp loss for the electric fan means it absolutely cannot move the same volume of air as the mechanical fan - it moves however many CFM regardless of RPM. That mechanical fan is moving mountains of air at 6,300RPM - something the electric fan cannot ever hope to do. However, it doesn't need to, and this is where the electric fans can have an advantage. The electric fans shine at idle and low RPM where the mechanicals perform the worst. But the electric fan cannot move the air the mechanical fan can move at 6,300 RPM...if it could, it would cost more HP because you'd need a huge electric motor to turn it.
One of the primary reasons the electric fans "free up HP" is because they do not move nearly as much air as a mechanical fan at higher RPM. However, they make up for it at idle and low speed. But this is not the same thing as saying they are more efficient, because they are not. However, this is why the modern mechanical fans, particularly in the severe duty packages, are very aggressive, multi-blade mechanical fans with a large thermal clutch. Even a direct-drive flex fan will usually beat out a stock muscle car fan, few of which had a clutch. So the Car-Craft article, while correct in that application, is not doing an apples to apples comparison.
There's a curve based on RPM and CFM that will show you where a given mechanical fan will being to flow more air than a given electric fan. If your vehicle operates in this area of the curve, a mechanical is a much better option. Most of our street driven cars/trucks don't fall in this area, or if they do, very far into it.
There are a few applications where mechanical fans would be advantageous - high RPM, low speed - like tractors, rock crawlers, mud trucks, etc.
As the article points out, the simple mechanical fan is the "worst" when looking at HP loss and the clutch fan is next best. What they imply, but don't actually say, is that 1hp loss for the electric fan means it absolutely cannot move the same volume of air as the mechanical fan - it moves however many CFM regardless of RPM. That mechanical fan is moving mountains of air at 6,300RPM - something the electric fan cannot ever hope to do. However, it doesn't need to, and this is where the electric fans can have an advantage. The electric fans shine at idle and low RPM where the mechanicals perform the worst. But the electric fan cannot move the air the mechanical fan can move at 6,300 RPM...if it could, it would cost more HP because you'd need a huge electric motor to turn it.
#38
07-29-2015, 09:34 PM
I have a bit of electric fan knowledge that may help.
first depending on your electrical system it may not be an option. a 75 amp alternator can barely handle my dual contour fan setup on my mustang. if i had stop and go traffic for a half hour it could very likely kill the battery.
the start up spike on them is insane. close to 90 amps on the lincoln mark viii fan.
if you get a electric fan go with a fan controller like the flexalite units that have temp control, soft start feature to grt ride of the spike and variable speed.
imo, if you have the original motor or something close I would stick with mechanical. if you already swapped the motor then all bets are off and go for broke
fyi older ford contours, ford taurus and lincoln mark viii have the best and slimmest fans. depending on where you live can easily be found at a pick and pull
first depending on your electrical system it may not be an option. a 75 amp alternator can barely handle my dual contour fan setup on my mustang. if i had stop and go traffic for a half hour it could very likely kill the battery.
the start up spike on them is insane. close to 90 amps on the lincoln mark viii fan.
if you get a electric fan go with a fan controller like the flexalite units that have temp control, soft start feature to grt ride of the spike and variable speed.
imo, if you have the original motor or something close I would stick with mechanical. if you already swapped the motor then all bets are off and go for broke
fyi older ford contours, ford taurus and lincoln mark viii have the best and slimmest fans. depending on where you live can easily be found at a pick and pull
#39
07-30-2015, 02:49 AM
Laughing Gas
I have an electronic one on my truck because the distance between the old fan and the radiator was so large it wouldn't have been at all efficient. Mine didn't have a shroud, which would have made the difference. I haven't had it running yet. Would rather the old style look, but since I went aluminium radiator, decided to go thermatic fan as well.
What I didn't like was the kit which included a probe which you whack in your radiator hose or buy an adapter which you then have to fit between two pieces of hose to fit your probe. I ditched that and bought an electronic temp sender which sits in the fins. It is highly adjustable and can control more than one fan if needed.
I think it depends on the style or the modernity of your engine bay somewhat.
Got a nice matching shroud made up for it to add to its efficiency. Should work very well methinks
#40
07-30-2015, 08:29 AM
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imo, if you have the original motor or something close I would stick with mechanical. if you already swapped the motor then all bets are off and go for broke
#41
07-31-2015, 12:48 PM
More Turbo
I went with the exact same 94-97 4.6L Tbird electric fan on my 55 the fan fits the original radiator so perfectly it would appear it was made to be there. I also used a two speed BMW temp switch and a two speed Volvo fan relay. Perfectly reliable and always comes on when needed. There is no whine from an electric motor just the sound of air being moved.
Highly recommended setup!
Highly recommended setup!
Hmmm.... I spent a lot of time looking at fans to take care of a cooling issue we had on our 351W in our 1950 F1.
For us it came down to how much room you have up front between your engine & radiator. If you have less than
5 inches you will probably need to go electric. The most popular fans out there are the Mark VIII fans & Taurus
dual fan set up's. They move an enormous amount of air & yes they do spike some high amps at startup. You will need
a high performance alternator.
We went with an 18 inch fan from a V8 Tbird - fit our radiator great & has the same motor & air volume as the Mark VIII fans.
Our temp sensor is a BMW 2 Speed sensor on 176/195 degrees - fits into the top of the thermostat housing.
Good luck over there. I think our salvage yard cooling set up was less than $150.
Ben in Austin
1950 F1
For us it came down to how much room you have up front between your engine & radiator. If you have less than
5 inches you will probably need to go electric. The most popular fans out there are the Mark VIII fans & Taurus
dual fan set up's. They move an enormous amount of air & yes they do spike some high amps at startup. You will need
a high performance alternator.
We went with an 18 inch fan from a V8 Tbird - fit our radiator great & has the same motor & air volume as the Mark VIII fans.
Our temp sensor is a BMW 2 Speed sensor on 176/195 degrees - fits into the top of the thermostat housing.
Good luck over there. I think our salvage yard cooling set up was less than $150.
Ben in Austin
1950 F1
#42
07-31-2015, 01:31 PM
Hey Jules,
Thanks for that post - that's reassuring to know others have used the same set up with no issues. We bought ours off of Ebay & it fits & works great. You can spend some real money on electric fans et al. This set up was under $150 for anyone looking for a reasonable engine cooling solution.
(V8 Thunderbird 18 inch fan, BMW 2 speed switch, Volvo 2 speed Fan relay).
Ben in Austin
1950 F1
Thanks for that post - that's reassuring to know others have used the same set up with no issues. We bought ours off of Ebay & it fits & works great. You can spend some real money on electric fans et al. This set up was under $150 for anyone looking for a reasonable engine cooling solution.
(V8 Thunderbird 18 inch fan, BMW 2 speed switch, Volvo 2 speed Fan relay).
Ben in Austin
1950 F1
#43
02-14-2016, 09:18 PM
Hi Drewski 2, would you mind telling what fan and shroud combination you're using in the setup below? I went through your garage journal post hoping to find details there ...
I'm running a 400 sbc which is notorious for overheating. After playing around with several different fans and shrouds, I finally found that a clutch fan with a shroud that covers the entire radiator and the fan would keep the engine at 180 degrees whether moving or sitting in traffic.
#44
02-15-2016, 10:55 AM
Fleet Mechanic
I tried electric fans here in Arizona on three different vehicles and they did not work for me in this heat.
I had two 66 Mustangs with 5.0's, a Toyota with a 2.4, and a Suburban with a super charged 350.
The Mustangs had cooling issues in the summer only. They have small radiators which is the biggest problem. I put a 4 row high efficiency brass rad in one and a two row aluminum in the other which helped a lot. I tried 16" Flex-a-lite's with built in shrouds. Overheated in traffic. Built better shroud to suck ALL air through rad. Still overheated.
Went to six blade mechanical fan with shroud and fan clutch. Stock shroud sucks so plugged some air gaps. No more overheating in summer.
The Toyota truck was a stock 4 banger and didn't overheat. I thought I could save some power for the little engine and be able to shut off the fan when going through water and have plenty of cooling when rock crawling. Stuck the same 16" Flex-a-Lite on. Just about took up the entire radiator. Should work great. It didn't, ran hot and boiled over at slow speeds. Back to stock fan.
The Suburban had LOTS of power and a heat generating transmission. Pulled all my gear and family AND my boat up mountain grades in this heat. I had a huge BeCool aluminum radiator, Edelbrock water pump, stock shroud and clutched fan. Also had the biggest B&M Racing trans cooler with it's own shroud and electric fan mounted so it wouldn't impead air to rad.
Ran cool except when loaded and pulling grades in 110 degree heat. Slowly creeped up. I tried TWO of the same Flex-A-Lite fans. Overheated.
I had room so I left the two electric fans on the back of the rad inside the stock shroud and the stock fan and clutch. Almost touched but worked.
When pulling the mountain grades I switched on the two electric fans and temps came down. When going over the summit the engine upshifts and fan and water pumps slow. The electric fans helped it cool down faster ready for the next climb.
I don't remember the CFM rating of the Flex-A-Lite fans. They seemed to move a lot of air. I also had a Spal I tried on the Mustangs and the Toyota but, the Flex-A-Lites were better. Just my experience here in this desert heat.
Last summer my neighbor came by with his newer Ford pickup. Said it started overheating. I could hear the electric fan running and asked if it had two speeds. He didn't know and either did I. He had to have it towed in to dealership. High speed wasn't working for some reason. I don't know if it was the fan or something controlling it.
I think if I was going to try electric again it would be a large factory OEM unit.
Scott
I had two 66 Mustangs with 5.0's, a Toyota with a 2.4, and a Suburban with a super charged 350.
The Mustangs had cooling issues in the summer only. They have small radiators which is the biggest problem. I put a 4 row high efficiency brass rad in one and a two row aluminum in the other which helped a lot. I tried 16" Flex-a-lite's with built in shrouds. Overheated in traffic. Built better shroud to suck ALL air through rad. Still overheated.
Went to six blade mechanical fan with shroud and fan clutch. Stock shroud sucks so plugged some air gaps. No more overheating in summer.
The Toyota truck was a stock 4 banger and didn't overheat. I thought I could save some power for the little engine and be able to shut off the fan when going through water and have plenty of cooling when rock crawling. Stuck the same 16" Flex-a-Lite on. Just about took up the entire radiator. Should work great. It didn't, ran hot and boiled over at slow speeds. Back to stock fan.
The Suburban had LOTS of power and a heat generating transmission. Pulled all my gear and family AND my boat up mountain grades in this heat. I had a huge BeCool aluminum radiator, Edelbrock water pump, stock shroud and clutched fan. Also had the biggest B&M Racing trans cooler with it's own shroud and electric fan mounted so it wouldn't impead air to rad.
Ran cool except when loaded and pulling grades in 110 degree heat. Slowly creeped up. I tried TWO of the same Flex-A-Lite fans. Overheated.
I had room so I left the two electric fans on the back of the rad inside the stock shroud and the stock fan and clutch. Almost touched but worked.
When pulling the mountain grades I switched on the two electric fans and temps came down. When going over the summit the engine upshifts and fan and water pumps slow. The electric fans helped it cool down faster ready for the next climb.
I don't remember the CFM rating of the Flex-A-Lite fans. They seemed to move a lot of air. I also had a Spal I tried on the Mustangs and the Toyota but, the Flex-A-Lites were better. Just my experience here in this desert heat.
Last summer my neighbor came by with his newer Ford pickup. Said it started overheating. I could hear the electric fan running and asked if it had two speeds. He didn't know and either did I. He had to have it towed in to dealership. High speed wasn't working for some reason. I don't know if it was the fan or something controlling it.
I think if I was going to try electric again it would be a large factory OEM unit.
Scott
#45
02-15-2016, 11:03 AM
More Turbo
Scott, I would think your problem was the flexallot fans. Most everything I have read about aftermarket fans is not good.
For my 55 I went with a 4.6L thunderbird electric fan, the plastic shroud is almost the perfect size as though it was made for it! I think there is only a 1/2 inch gap at the bottom that is not shrouded.
For my 55 I went with a 4.6L thunderbird electric fan, the plastic shroud is almost the perfect size as though it was made for it! I think there is only a 1/2 inch gap at the bottom that is not shrouded.
