electric fans????

[jimraelee]

As I read thru the many posts, and think of gas mileage savings, why do I not see any threads about installing a elec rad cooling fan on our diesels??? saves a little on gas mileage??? I did read a post about converting the fan clutch to a diff style, one that operates at a lower engine rpm... With the slow speed of a diesle I would think that would cuase lots of resistance.

 

[Full Monte]

There is no free lunch

If you change from a stock fan to an electric one, you will increase the electrical load on the alternator, meaning it will take more engine horsepower to make it turn (increase the amount of energy to turn the alternator). On the other hand, as truck speed increases and ambient temperature drops, the need for a fan decreases, so an electric fan may get turned off by its thermostat. In this case, you save the energy required to turn a fan. I don't know how much it will affect mileage, but would guess that it would be a small number. Increases in mileage would likely be best accomplished by slower freeway speeds (55mph) and smoother/slower acceleration.

 

[adrianspeeder]

This is a great debate over on FSB. The increased electrical load from a fan, is easily offset by a better alternator like the 3G from a Taurus or Stang, making that point a non issue.

The real problem is moving enough CFMs of air. A dual electric fan setup just about equals a mechanical fan with the clutch locked. This is with the electrics turning max. One craps out, your SOL.

People also cheap out on the fan controls, pulling over 50amps needs some $ invested in the switchgear and relay controls to be reliable.

Adrianspeeder

 

[jimraelee]

If you change from a stock fan to an electric one, you will increase the electrical load on the alternator, meaning it will take more engine horsepower to make it turn (increase the amount of energy to turn the alternator). On the other hand, as truck speed increases and ambient temperature drops, the need for a fan decreases, so an electric fan may get turned off by its thermostat. In this case, you save the energy required to turn a fan. I don't know how much it will affect mileage, but would guess that it would be a small number. Increases in mileage would likely be best accomplished by slower freeway speeds (55mph) and smoother/slower acceleration.

ummm do some checking... a elec fan does take energy, but seeing how most drive over 30mph, the fan is turned off and there is less resistance vs the constant spinning of the fancluch mechanical setup... the amount of extra amps need for the fan is minimal... typically from reading most threads on numerous forums, there is about a 1mpg gain when making the switch... in the Internation Scout froums, we typically see guys making a switch to elec fans and efi and gain up to 5pmg for the combination, but thanks for the thoughts

 

[swampdigger]

When you need a fan, electric fans will be less efficient. A mechanical fan of same CFMs will work the engine less, than the load placed on the alternator by the electric fans.

But when you don't need the fan, electric fans require zero energy. A clutch driven mechanical fan loads the engine lightly. Although ****, have you turned a fan with a nice clutch?

In my experiences, you can trust a mechanical fan. At least when the clutch goes haywire, it gets stuck ON for the most part. And when the cltuch goes, they can make some good warning noises first.

But truck that rarely tows anything, and runs in cooler climates, electric fans are prolly the way to go.

 

[MUDKICKR]

i put an electric fan on my jeep and it made a world of differance, plus no worries about the fan clutch coming apart and going through the rad, which is why it has a ele fan now. but the power and milage is worth the change, i recommend it to anyone and will be doing this swap to my diesel trk as soon as money allows. I overdo everything so to make it foolproof. also another good thing about an ele fan is it keeps under your hood cleaner when you go mudding.

 

[jimraelee]

But truck that rarely tows anything, and runs in cooler climates, electric fans are prolly the way to go.

YUP YUP... I will tow the boat 2000lbs, to the coast maybe once a month. Small hills 1600ft elavation. and it mostly drives me to work and back, Oh in the summer we might get a week of 90+ temps... Mostly rains in 60's with some teens in Jan-Feb...

 

[suv7734]

Article from the Tech section...

http://www.oilburners.net/forums/showthread.php?t=17484

 

[Agnem]

Thank you!


Short version - nobody has proved an electric fan can hold up to the most extreme towing conditions.

 

[Whit]

on any diesel ya only use 30% of the cooling capacity for normal driving.........when ya tow thats a different story..ya need it all


bottom line is if ya run around empty all the time an electric fan setup will be OK but if ya tow then forget it

also the use of air conditioning when not moving is a huge load on the system


electric double fans can get ya 8500 cfm..........................a Cummins 5.9 needs 8800 cfm......I dunno bout the Fords though


air to air exchangers are poor at best so only expext a max effeciency of 80% MAX

 

[7.3shrk]

Unless you make your own, how long will it take in fuel savings to make up for the initial outlay of the fans? I have seen the good fan set ups going for a bit over $300.

 

[jimraelee]

Ok, I get it... leave the elec fans to the cars

 

[Agnem]

Not trying to disuade you from trying it. Just pointing out the empirical data to date. That's not to mean it cannot be done. My personal feeling is that a much larger radiator will be needed. After all, locomotives have electric fans, and they are getting rid of the heat generated by over 3000 HP continuously all day long, so it CAN be done.

 

[JPR]

Unless you make your own, how long will it take in fuel savings to make up for the initial outlay of the fans? I have seen the good fan set ups going for a bit over $300.

Assuming it makes a 1 mpg difference and your starting with 13 mpg and fuel costing $3.16, heres what I came up with
$300 initial cost / ($3.16 per gallon/ 13mpg - $3.16 per gallon/ 14mpg) = 17,278.5 miles

 

[jimraelee]

Mel... I know.... nobody was being rude, jus pointing out the facts... but sometimes its not a $$$ spent value exchange. Theres also the "1 off" factor

JPR... umm send some of that $3.16 gas over here please... were pushing $3.60, and some have claimed $4gal.... Its a crying shame that diesel fuel, the cheapest to make with the least refinements is costing more the Premium fuel I put in my Go fast car...