Electric Fans- revisited

[Craig M]

I know it has been discussed before. Useing an electric fan or fans for the radiator and eliminating the belt driven fan from the engine. This saves horsepower for the engine, when it is needed most, on big hill climbs etcetera. The prior thought on this forum was that the available fans were not powerfull enought for major towing or hill climbing. They were maybe ok for light-weight driving. This idea is still one of the easiest ways to get engine horsepower. Are there any new or better fans out there yet that will work with our diesels? Anyone have a custom fan set up that they find works good.

[More Power]

Adequate engine cooling has always been a challenge with the 6.5. Those who have experienced overheating might agree that cooling is more important (or at least as important) as having more power.

The highest flow dual-electric fan sets pull 5200 CFM. A 21" 9-blade engine-driven fan can pull more than 10,000 CFM at 3000 rpm.

That said, our Duramax Project truck will in all likelyhood be using a dual-electric - for the power advantage.

MP

[pannhead]

dont forget that the 5200 cfm rating is a ZERO static...a radiator,trans cooler,oil cooler,a/c condensor is ALOT of static :eek: ...i wonder what the cfm rating is with all our "static" ???

[HowieE]

My thoughts on electric fans come down to this. Yes an electric fan will reduce the HP drag on the engine and is an ideal soultion for short run such as drag racing, were the heat generation will occur after the HP need. On a hill pull an electric fan will come in while heat is being generated and run off the battery. However at some point that battery has to be recharged and that HP load is transmitted to the altenator. Another consideration is that an electric fan produces cooling in a square wave function, it is either on or off. While the thermostats will have some effect on this square wave the net result will mostlikely be much larger swings of temperature within the engine it's self.
As long as I have been towing I have alway had a thing about heat. With periodic cleaning of the radiator, inside and out, and with selected auxiliary coolers on the engine oil and removing the transmission oil from the radiator I have never seen elevated temperatures in either of my diesels. Normaly running at 185 to 195, the point at which my clutch fan come on. The highest I can remember 215 going into Grand Cashe AB from the north side, a nice hill.

[Randee of the Redwoods]

Not being mean, but how often are you at 3000rpm for that Dmax fan to pull the rated CFM? I don't do 3000rpm going down the highway at 65. I know vehicle speed and other factors are involved in cooling, but the way I see it, the electric fans have the advantage of being separate from the engine, therefore engine speed(rpm) has nothing to do with cfm rating. In stop and go traffic(and to some extent towing since speeds are lower), the electric fans have the advantage.

[Dvldog 8793]

Howdy
I think I said this one other time on a similar posting. What about hydrolic fans? The hummers that I grew to love and hate had radiator mounted fans that operated off of the power steering pump. These units had a temp actuated valve on the fan itself much like a clutch fan. When these babies took off it sounded like you had an air plane under the hood! :eek: The only down fall I ever saw was when they kicked in underwater, the plastic fan blades did not like it all :D
Anyways, just thought it might be an idea. I don't know how much they move or how much they take in terms of power from the PS system.
Just an idea....... ;)
L8r
Conley

[Kidd]

Hydraulic fans sound like an idea. I notice that Cat is swithching most of their equipment to hydraulic fans. They say they save power, and the best part is they are variable speed depending on heat, not engine rpm.
K.D.

[grape]

Never towed a trailer with my 6.2 k5......but did drive for 2 years with no fan at all. AC gets warm at a stoplight but that's it. Wouldn't recommend it for towing.

[Craig M]

Hydraulic fans have the advantage of variable speed, but are still a drain on the engine power. The hydrauic pump will be driven off the engine or the transmission. You are taking power from the engine to run the hydraulics. The electrics are taking power from the battery. Battery can be charged back up as you go down the hill or on the flats when you have pleanty of reserve power available.

[Dvldog 8793]

The hydro fans ran off the power steering pump, how much more of a drain would it be? The pump is already running. Hummers ran the fan, brakes and powersteering. I don't know the specs of the pump.
L8r
conley

[Craig M]

I had not heard that hydraulic fans were run off the power steering pump. For the kind of power required to run the fan, would not have thought that the power steering pump would be sufficient. If it work it works, let hear from someone that has it!

[CareyWeber]

I thought the hydraulics were just used to operate the fan clutch not to actually turn the fan. :confused:

[vernj4]

HowieE

and removing the transmission oil from the radiator

and replace the tranny cooler with what? and where mounted?

Thanks,
Vern

[HowieE]

When I mentioned removing the transmission oil from the radiator this is what I do. Remove the trans piping that connects to the radiator and connect them togeather with a piecs of hose. The radiator runs at a temperature around 180+ degrees and can not impart any cooling below that temperature. Yes GM has installed an additional cooler forward ot the radiator to add aditional cooling below that which the radiator may provide, but I would rather not have my transmission need to go above 180 degrees before cooling takes place.
I have installed an aux fan driven trans cooler under the truck in the output hose coming from the trans that has a thermostat that comes on about 160 degrees. Any oil leaving the trans above 160 will turn this cooler on. from that cooler the oil goes forward of the radiator to the stock cooler and gets what ever additional cooling the air flow will provide.
While the convertor is locked my trans holds 150 degrees while towing.

[Peter J. Bierman]

The big advantage off the hydraulic fans is that they only draw power when needed.
If the engine temp is low the fan will run on a stationairy rpm like 300 rpm.
When engine temp increases the fan speed up a bit to keep cooling in proportion with the temp.
Only on a very hot engine ( rare occasion) the fan runs at max rpm.
The same goes for electric fans but they are not proportional and switch in "too late "
The hydraulics don't kick in but slowly rise rpm if necissairy
Wonderfull system but expensive.
Construction equipment use it more and more becouse off the fuel saving and noise reduction, but they allready are equiped with hydraulics.

Peter

[GMCfourX4]

Flex-A-Lite makes a 5500 CFM dual-electric fan for our trucks, which I have on mine. The electronic controller lets you set the "On" temp to pretty much whatever you want (you get a wide range, it doesn't say what, I used an IR thermometer to determine when coolant was flowing through the rad. and set it to about 180*). When the "On" temp is reached, the fans come on at 60%, and ramp up to 100% over the next 10*, so when the temps in the radiator are at about 190* (at the inlet) the fans are pulling at 100%. They also come on automatically at 60% when the A/C is on, and you can hook up a manual switch to make them stay at 100% or stay off (for water crossings, not a problem I have). I haven't done too much towing since I installed them, but I towed a 4,000 lb Volvo 960 around with a COld Front on (blocking off the grille, so the only air was coming from the bumper holes) and I never had the needle move over normal operating temp. These things move a LOT of air, and my mileage has gone up a bit (my mileage is about the same, or maybe even 1/2 mpg better running winter fuel and electric fans than it was on summer fuel and the clutch fan). One thing I will say is that when I installed the electric fans, I took my rad out (i flushed the system) and took a good look inside (at least as much as I could see) and it was perfectly clean. I cleaned an enormous amount of crap out from the fins, though (and it didn't look dirty at all..... until the water I sprayed through the fins was coming out the other side black). There was also quite a bit of crud stuck in the fins of the A/C condenser and oil cooler.

-Chris

[Stage1]

RE: FYI radiator infomation

I am new to diesels and their cooling issues. Experience w/ Chevy 502-high performance mods, and dual A/C units in a very tight engine comparment. Black car weights about 5 tons and the GM high performance cooling system w/dual electric fans kept this system working at idle in 100 degree heat. It also worked great under heavy load ( speeds of 80 to 100 MPH). This was GMs best system back in 1999, not sure what they have now. The GM system was far superior to aftermaket products in 1999, especially their dual electric fans.

What is the source of the engine heat problems.
thanks,
Les

[gmctd]

Read "Removing theoretical cooling etc" on page two, on this Forum.
(Ignore the silliness at the end - I was very sleepy, and threw in some TIC to wake up for editing)

Or, do a search on the subject - should be a wealth of info there