Mechanical fan vs. electric conversion....real numbers to compare

So, here is the backstory to all the numbers I am about to present to you.

When I first started using my truck to ill my 7000 pound camper, the cooling system was shot. I know this now. The radiator was full of mineral deposits. The coolant was unknown. Etc..

I couldn't keep the truck under 230 towing at all. And close to that not towing at freeway speeds.

Last year, I changed the cooling system. Champion radiator, motorcraft water pump and thermostat. 65/35 distiller water to fleetcharge with purple ice additive. Added a coolant filter. New radiator and heater hoses. I also decided I would do the electric windstar fan conversions controlled by a dccontrols.com controller(which is awesome btw.).

It was cooling great unloaded, and ok loaded, unless you had to pull a steep grade at low speed.

I decided to swap the mechanical fan back on, which I thought still worked good, and it does.

I have logged all he average tips I would see on my gauge, located in the overheat port in the front of the drivers side head. Checked them at 55 mph and 70 mph, unloaded and towing 7500 lbs.

I found the results were quite interesting. Not what I expected at all, especially at speed unloaded.




Old crusty radiator. And mech fan

Outside ambient air temp-50f

55mph unloaded. 210
70mph unloaded. 225
55mph towing. 230
70mph towing. 230+


New system/electric fan.

Outside ambient air temp-85f

55mph unloaded. 195
70mph unloaded. 210
55 mph loaded. 210
70 mph loaded. 230



New system/mech fan

Outside ambient air temp-92f

55mph unloaded. 195
70mph unloaded. 195
55mph loaded. 200
70mph loaded. 210



I found it truly interesting the large difference at 70 mph, both loaded and unloaded. Perhaps the radiator shroud area on the windstar fan was blocking airflow?

Most fans I've found pull a lot of power, are large, but don't move that much air. On my SC gasser I struggled worth electric fans for a few years until I found some cheap JDM's (two twelve inch fans, no shroud) on ebay and took a crack wroth them. The gasser would only see 225* while towing 4 tons behind its 3 ton self on hot summer days. Going to take a song with 2 larger ones on the 7.3L later and see if it's just the difference in how the 300 sixer operates.

I

Just goes to show you that a mechanical fan is never fully disengaged with numbers like that. I've heard reports of some semi fans requiring 50+ horsepower to turn, and being able to move 30,000 cfm. Seems crazy high, but I definitely feel a dip in power when mine kicks in.

Any electric fan setup I've seen usually states it's not meant for towing.

kas83 said:

Just goes to show you that a mechanical fan is never fully disengaged with numbers like that. I've heard reports of some semi fans requiring 50+ horsepower to turn, and being able to move 30,000 cfm. Seems crazy high, but I definitely feel a dip in power when mine kicks in.

Any electric fan setup I've seen usually states it's not meant for towing.

Click to expand...

On 2 large pulls on the way to the campsite, I got the temp up to 230. The fan absolutely kicked in when the temp hit 230. It did seem like I could hear it a little bit when temp got up to 215-220.

One of the reasons I went with the e fans when I did was the loss of power when the fan kicked in. Since that time though, I have installed my junior moose pump, and intercooled my banks sidewinder kit. When the fan kicked in, I feel no noticeable drop in power now. I just let the skinny pedal down and listened to the roar as the temp cooled off.

My EGTs were down as well m those hard pulls with the fan kicked in. I suppose the intercooler is doing its job there.

So the mechanical fan is there to stay?

whitehorse said:

So the mechanical fan is there to stay?

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Yep.

When my radiator was junk, it stayed locked all the time when on the interstate. Temps were just too high. It doesn't do that anymore. Only went into full lock twice when I was pulling some steep grades going up mt. Magazine. Our states highest point.


I guess I should edit the post to include the outside ambient air temps.

whitehorse said:

So the mechanical fan is there to stay?

Click to expand...

Yes. Our fans will pull about 10000 cfm with a properly working fan clutch. No electric fans made can touch that.

As noisy and annoying the mechanical fans can be, they work good. My 15k lb RV has a gasser (460), replaced the bad clutch with a good one, it only has to run a minute or so to get the engine temp down significantly.

This is exactly why I have kept the mechanical fan on mine. I have a new fan clutch to install, but I really don't know if my old one is bad. I can't seem to get my temps up enough to see if it will kick in. Unloaded the highest I can get my coolant temp is the 210-212* range. That is cruising at 75-80mph up the hills we have around here. Guess I need to tow heavier and find some big hills....my average load has only been about 5k.

A search also found some info that detailed how to adjust the fan clutch engagement temp for those that want it to engage at a lower or higher temp. The basic idea is that you adjust the length and curve of the clutch thermostat spring. Also a good idea to make sure it is good and clean.

Jayro....go take a vacation to Knoebels Grove Amusement park in Central,PA.... you will find plenty of hills to put that van to work...plus its one of the great underrated parks in the country.

http://www.electricfanengineering.com/app_truck_turbine_electric_fans.html
here are some big cfm rated fans

ironworker40 said:

http://www.electricfanengineering.com/app_truck_turbine_electric_fans.html
here are some big cfm rated fans

Click to expand...

I would have tried one of those, but the clearance required between radiator and engine isn't big enough on our trucks.

They all need 7.5 inches or more. My truck only has about 6 at the
Most.

Glad your temps were better on that last trip. I had been wondering how it went since you switched back to the mech. fan.

The 50+ HP claims are somewhat inflated. I did some numbers at one point and came up with a max of ~5 hp for the IDI mechanical fan. It also moves something like 15k cfm IIRC - hard to beat with an electric.

I've long said that the power and mileage loss with the mechanical fan is far less than claimed, so the benefits of electric aren't that much. A properly working and low temp configured fan clutch will work far better for anyone running heavy on in the hot parts of the state.

The best solution though is the stock fan with an electric clutch, but it's a pricey upgrade. Very very nice to have though.

Has anyone run a pusher auxilliary fan in front of the condenser. It may help out the ac at idle and may keep your mechanical clutch from locking up so soon but when the engine gets hot the mechanical wood be there to cool it down