radiator electric fan??

[byates2]

Im looking into putting dual electric fans on the radiator instead of having the fan on the engine.

The ones im looking at are made and sold by jegs and puts out 2600 cfm and has 12 inch fans or they have one that has dual 11inch fans that puts out 2760 cfm. the 12 inch draws 24.8 amps and the 11 inch only draws 22 amps

the 11inch works only as a puller where as the 12 inch works as either push or puller.
Which would be a better choice?

And also im looking at the thermostat to turn on at 185 and off at 170 or to not have a thermostat and just always have the fans running, or even throw a manual switch on it so i can turn the fans on and off whenever i want.

Would it be better to set them up to always be on or to have a thermostat??

[BMERDOC]

For installation purposes pullers are always easier to install than pushers. Running a thermoswitch means it automatic and you never forget to turn it on! Both seem overkill on CFMs but I didn't crunch numbers

[plummen]

Personally after spending more years as a plumbing/hvac contractor than id like to admit,I think a puller fan would be more efficient as it would tend to it less turbulent pulling air through the coils rather than trying to shove it through like jello
Ive been throwing differant ideas around for cooling my bigblock 69 project also,Im leaning towards the biggest mechanical flex fan I can lay my hands on.
The main reason Im leaning towards the mechanical fan is fewer things to worry about on the road ,ive seen lots of cars/trucks over the years with bad fans/thermostats that wont turn on.I figure as long as my belts spinning ive got a fighting chance to get somewhere to fix it anyway

[BMERDOC]

To add to the discussion...Plummen, since you know something about conditioning air, is there something to be said against over CFMin a cooling system? What is the term for over conditioning a house? Isn't there a term for it? Do you think this would apply to him wanting to add a fan? Would there be a comfort problem with a big fan colling down the rad when switched. Just a thought...

[plummen]

Originally Posted by BMERDOC

To add to the discussion...Plummen, since you know something about conditioning air, is there something to be said against over CFMin a cooling system? What is the term for over conditioning a house? Isn't there a term for it? Do you think this would apply to him wanting to add a fan? Would there be a comfort problem with a big fan colling down the rad when switched. Just a thought...

The biggest mistake people make with cooling a house is oversizing the outdoor condensing unit in my experiance,if a unit is too large it wont cycle/run long enough to remove the humidity from the house.
Normally id suggest going 1/2t over on the sizing of the a-coil above the furnace compared to outside condensor rating which gives more surface area for pulling humidity out of the air as it passes over the coil,which also boosts the seer(seasonal energy efficiency rating ) of the a/c system.
As far as over cfm'ing the system if the drive on the furnace is sized right you should have no issues,the cooling side is designed to run on the high speed side of blower which will give you the maxium airflow the furnace or air handler can put out
As far as over cooling the radiator with the electric fan youd have to talk to the supplier about what combination of parts youre running,personally ive always had good luck with mechanical fans and the proper fan shroud to guide the air through the radiator

[solar649]

Ok. ill throw in my two cents on this. I think your comparing apples to oranges here..

the stock fan is 18 inches with large blades. It pulls different air amounts as you are at idle or at 5k. With that. 2k CFM is small. the mechanical at an idle would pull around 3500-3700 cfm.

Yes we can get into the clutched , un clutched discussion. blade flattening at speed, etc.

when it comes to air flow over the fins of the radiator we are looking for more is better. the more air flows over the more heat is removed. This is not like an AC system that regulates its self in cycles. The thermostat opens and closes as the heat in the block dictates. So the cooler the water going in the more heat can be removed.

Personally I am running a double core aluminum Radiator with dual 1.25 cores. I run a 160 degree thermostat, and a 19 inch electric fan that flows 6500cfm. I can tell you that you cant touch my radiator on the drivers side at temp but can lay your face on the radiator cap on pass side.
I have used a cap with a thermostat in it to see what the temp going out of the radiator was compared to the 160 degrees coming out. I get 85-90 degrees on the outlet side of the rad.

so with this the water can gain 70 degrees of heat from the block before it would open the thermostat. where as it the incoming temp was 130 degrees you would only remove 30 degrees of heat before opening the thermostat. So it would require more water floow to remove the same amount of heat from the block.

Yes, I understand you can over kill the fan and the cooling system. Yes my cooling system looks to probably be able to support a 500 hp big block and not over heat. So my 275 hp small block does not need that much. But this leave room for expansion, and growth in the future with out the added expense of new cooling parts.

As I said this is just my opion and it probably doesnt count for anything. I just believe that 2500 cfm does not meet your needs. you will possibly have issues sitting in traffic, parades, slow cruises, etc. I am sure on the highway and crusing at speed it will probably be ok. But you have to think worse case issues, not optimum driving.

I hope I didnt upset anyone, and dont take it that I dont know a little about this as I have been building road race porsches and kit cars for ten years now.

[MagmaJct]

Okay, here's my take on this topic. I believe that we can compare apples to apples, or oranges to oranges, as the case may be. Both an electric fan setup and and a belt driven clutch controlled fan accomplish the same goal with different methods. What are the requirements?

At higher vehicle speed, ram air, that is air we're "ramming" the radiator into, is sufficient to keep a properly functioning radiator cool enough to prevent over heating. In this instance no fan is needed at all.

However, at lower speed city driving, which includes stopping, little to no air flows through the radiator. This would lead to over heating.

Now we could add a fan, either belt driven without a clutch, or an electric fan that's always on, but then it would run all the time the engine is running, whether we are moving or not. This is a waste of power at higher speeds.

A fan clutch and a thermostat on an electric fan accomplish the same goal. In the case of a clutch, it allows the fan to "free wheel" so that it consumes very little power when it's not needed compared to a fan without the clutch. How much power is still consumed I don't know. In the case of an electric fan the thermostat shuts the fan off when the coolant in the radiator doesn't need cooling.

The reason that most people wish go electric is to reduce power consumption. But leaving an electric fan on regardless of the demands of the cooling system is worse than a clutch controlled belt driven fan. A thermostat allows the fan to turn COMPLETELY off.

What would I do?

Our 2005 Uplander has twin cooling fans. They are controlled by the engine management computer. 3 controls relays either turn the fans off, turns them on in a series circuit, that is, they run slower, or turns them on in a parallel circuit, that is, they run at full speed.

The nice thing about the two speeds is the temperature can be controlled in stages using less power, and making for a quieter engine (at low fan speed.) If the lower speed is enough to keep the engine cool, then the high speed never comes on.

If I converted my truck to electric, I would seriously consider a dual fan setup with two thermostat settings, or two thermostats, that allow for a slow, and a full speed setting.

Let us know what you end up doing.

[dbstepside]

i'm running a built 454 with a 12" pusher fan that is key operated and i hardly ever get temp gauge over 190, yes i may be losing a little power on the open road but i don't have to worry about the thermostat stickin and not kicking the fan on and takin the chance of boiling my engine i have thought of putting a switch on mine but just so when it's cold i can build heat up quicker since at only 190 my heater doesn't kick in to quick and then it's still an old truck so keeping heat in there isn't easy either in the winter either.

[plummen]

Theyve all got their advantages,as long as your truck stays cool thats the goal of any cooling system.
I guess im just a low tech keep it simple kind of guy! I dont like sitting in the middle of nowhere when things break,if a relay goes out in the on me in a small town in western nebraska in my experiance im going to be sitting for a while,where as if I lose a fan/alternator belt chances are pretty good im gonna be able to get one of a junk car sitting in a farmers field if need be to get me to civilization!
As far as the little bit of horsepower I give up,I figure I can check the air in my tires and clean the junk out from under my seat to make up for that little bit.
Not to mention that extra draw on the electrical system from that electric fan is going to keep that alternator working harder which is also a drag on power,either way these are pick up trucks not pro-mod drag cars so i dont think we have much to worry about!

[plummen]

heres one of my other never ending projects,my 74 kaw z1900 turned 1385 turbo/nitrous bike.
yeah i know all about getting every bit of hp out of a project!