Replacing engine fan with electric one, MPG increase?

[aldive]

Driving down the road the stock clutch fan is hardly pulling any power from the engine at all. When the electric fan is used it still must pull power from the alternator which is also will take more power to turn when required, in most situations there will be no difference and if there is it will be very small, certainly no where near 3MPG, more like .5mpg at best. If it ain't broke don't fix it.

My e fan is not running at highway speed.

I picked up a good 1.5 MPG when I wrnt electric. I could see a greater increase on a truck without other mileage boosting mods.

 

[aldive]

I run both the electric and the clutch fan

Pray tell, why?

as it can't provide good A/C performance in traffic. I've never overheated it while in traffic with the electric but it does not pull enough air across the A/C condenser to make it work effciently. This in Texas summers. when it hits about 90-100 outside is when A/C peformance starts to suffer.

Your e fan must be grossly undersized. What is the CFM rating?

Mine has never overheated ( even while towing ) in the hot Florida weather.

Having said that, there is a notable increase from about 12 in town to 16, and on the road, you can hear the clutch fan (replacement fan clutch) kick on and stay on and mileage goes from 19 with the clutch fan to about 22-24 with the electric fan.

Pretty amazing mileage increase. How did you calculate it?

 

[Blacksheep Josh]

I think what Aldive pointed out is what is confusing me...

 

[Texan01]

Pray tell, why?

Why? Excessive head pressure on the A/C system is the main reason. I prefer improved A/C performance in the summer than what my setup is capable of.

With my electric fan I see A/C manifold gauge readings of 350+ on the high side and acceptable 30-40 on the low side. With the clutch fan I see about ~175-200 and ~25-35 and improved A/C performance at idle to 2,000 rpm. This taken on days that it reaches 95-100F degrees ambient.

The electric fan is ok at idle in terms of performance but if you keep the engine at 1500-2000 rpm at very low speeds the compressor shuts off due to excessive head pressure from insufficient airflow across the coil.

The hardest part about swapping the fans in and out is loosening the fan from the water pump. to go from electric to clutch takes literally 5 minutes.

Your e fan must be grossly undersized. What is the CFM rating?

Never have guessed, but it never overheats the engine unless the relay dies.

I've put a thermometer in the fins of the radiator and it goes from 150 degrees to 120 in about 10-20 seconds at idle. Even when the relay died on a trail in Colorado and I nearly blew the radiator cap clean off the radiator from excessive pressure and temperature, once I could get in there and bypass the relay it cooled it off pretty quickly.

It's a ~15" fan with a nice shroud and it made for a nice clean install. It only covers about 2/3rds of the radiator area stopping at where the mounting tabs for the fan shroud are, so it's not the most efficient setup. I was going for a cheap swap, as I seem to remember it costing me about $80 total for the fan and the controller. This was done in 2003 if memory serves.

Pretty amazing mileage increase. How did you calculate it?

I calculate it by using the miles driven on tank divided by gallons used, using the trip odometer with the original size 235-75-15 tires and the normal way/routes I drive. So other than possible odometer error I've used this method for many years. Next week when I go back to Colorado I will keep detailed notes to check my claims or refute them if I am mistaken as I have a GPS unit now to verify odometer/speedometer accuracy.

I get pretty consistent 16-18mpg in town with the electric fan and when I remove the electric fan and reinstall the clutch fan driving the same way and the same routes I get 12-14. Last fill-up I got 15.6mpg with a fair amount of stop and go driving. with the electric fan.


Remember I have a replacement Hayden fan clutch not the factory Ford one. The Hayden clutch is much more enthusiastic in it's operation and tends to stay on all the time in the summer, in the fall I hear it when it's a cold start and it roars for about a mile before releasing. You have to rev the engine to about 4 grand in order for the clutch to release and let it resume thermostatic operation. Every replacement fan clutch I've used has done the same thing.


By OEM I mean Ford, GM, Chrysler, Toyota, etc, the automakers. I've not used a Ford electric fan as I could not find one that suited my space/size restrictions.

I have used Black Magic fans in other vehicles in custom applications and never have enjoyed listening to them run. They do work very well though.

 

[brihan]

In this thread and also in the HHO thread, it has been mentioned more than once that the extra load on the alternator will offset the expected mpg savings.

Couldn't you use a high output alternator and use a larger pulley on it. Wouldn't a larger pulley give it the leverage so it is not as big a load on the motor to turn the alternator? With a larger pully it would not spin as fast so I'm guessing a high output alt would help.

Does that make sense?

 

[aldive]

In this thread and also in the HHO thread, it has been mentioned more than once that the extra load on the alternator will offset the expected mpg savings.

With proper thermostatic control, the e fan is not running at all at highway speeds.

 

[duke16]

With proper thermostatic control, the e fan is not running at all at highway speeds.

Is it possible to rig a stock clutch fan to disengage at highway speeds?

 

[manaen]

In this thread and also in the HHO thread, it has been mentioned more than once that the extra load on the alternator will offset the expected mpg savings.

Couldn't you use a high output alternator and use a larger pulley on it. Wouldn't a larger pulley give it the leverage so it is not as big a load on the motor to turn the alternator? With a larger pully it would not spin as fast so I'm guessing a high output alt would help.

Does that make sense?

even if you increase your alternators output, and then gear it down to lighten the load on the engine, it still takes a specific load input to produce a specific amount of energy output. you will basically end up with an alternator that produces about the same load and output.

 

[CopyKat]

like this one?
http://www.explorerforum.com/forums/showthread.php?t=196738

Have you checked clearances?? I run a Taurus fan in my B2 and with the dual core rad I couldn't get it in. The fan motor hit the water pump. I'm running a single core rad right now and I have about 3/4" clearance. My temps stay under 190° on the hottest days sitting in traffic. I've got my fan running on a switch as of right now. One day I'll get to installing a controller.

 

[Maniak]

Using an electric fan, IMO, will help mileage. At idle, when you need the fan to run it may increase the load on the engine since your pulling amperage power at idle but thats when the fan clutch is most likely the tightest.

Once moving and the coolant temp drops the fan completly turns off. No load on the alternator from it at all unlike a fan clutch..

In the f-150 I just installed a Taurus fan on you can really feel the difference in power using your SOTP dyno (seat of the pants).

The best way I can describe it is you feel the same difference in power that you feel when you turn the a/c on/off. You feel that amount of power gain with the electric fan.

I am comparing this to a vehicle with a Hayden Super Duty thermal fan clutch. This means when engaged the fan is spinning 80-90% of the shaft speed. When disengaged it is still spinning 20-30% of the shaft speed. That means even when the mechanical fan isn't needed, it is still taking power. The Hayden thermal fan clutches engage at around 170F radiator air temp (about 200F water temp).

the above info about engagement is taken from http://www.haydenauto.com/catalogs/hayden/2007-hayden-fan-clutch.pdf

There are "less tight" fan clutches but for Southeran Az weather the Server Duty is the only way to go. So far the Taurus fan on the f-150 (with a 5.0L) is keeping up with the Southern Az heat (we haven't gone over 105F weather yet though).

~Mark

 

[atistang]

http://www.dccontrol.com/fancontrol.htm

thats a more pricey way to control the fan, but those controllers have more features

i have a black magic fan on my 89 mustang right now and it can't keep up when it is over 80 degrees outside, i'm going to a tauras fan soon

 

[lifeguard379]

Have you checked clearances?? I run a Taurus fan in my B2 and with the dual core rad I couldn't get it in. The fan motor hit the water pump. I'm running a single core rad right now and I have about 3/4" clearance. My temps stay under 190° on the hottest days sitting in traffic. I've got my fan running on a switch as of right now. One day I'll get to installing a controller.

i have plenty of room for mine. i trimmed the shroud so it was shorter and have it a Lil high on the rad(also have a 3" body lift). and only prob i have had is I'm on my second controller. it runs better now then ever did and you can feel the difference.

 

[seth247]

the clutch fan waystes a LOT of energy while the electric fan only pulls a few amps. Thats were your gain comes from

 

[Texan01]

On mine, I have the factory 90a alternator and it has no trouble keeping the electric fan running along with all the other accessories on at idle with lights and wipers running as well, only when you hit the rear defrost does the voltmeter drop some and you can hear the alternator start working.

Now I do notice when the e-fan comes on at idle as the lights dim or the voltmeter drops and recovers as it starts the fan motor, or motors if you turn the A/C on.

There still is a noticeable performance fall-off with the clutch fan on the engine vs the e-fan even on my marginal setup.

 

[CopyKat]

i have plenty of room for mine. i trimmed the shroud so it was shorter and have it a Lil high on the rad(also have a 3" body lift). and only prob i have had is I'm on my second controller. it runs better now then ever did and you can feel the difference.

Cool I've got a 1" bodylift and I couldn't make it work at all, short of moving the rad into the core support. 2 years on this setup (Single core) and I've only had one glitch, with the fan, out wheeling but it was caused buy a slew of other grounding problems.

I've seen a post somewhere about a guy making his own shroud for the fan. He cut the roung part out and made a sheet metal shroud and used it that way. Looked pretty low profile. Thinking I may do that sometime int eh very near future, when i pull the engine to replace a bunch of leaky gaskets.

 

[17fordguy]

ok this is slightly off topic for this but should help you all any ways i owned a 96 f150 i pulled the fan clutch and installed a fan from what i belive was a mini van of some make and model it had to fans on it one fan i set up thrue an e fan controler and the other was ran thrue a relay and a switch on the dash i could easly run both of these fans my, amp, and 10 fog lights on the stock alt and an interstate battery with no problems. with a 5mpg increase. will soon do this mod to my 04 explorer.

 

[Texan01]

I swapped my e-fan back to the clutch fan for the duration of July/August so my X is now back to stock configuration. I was getting 17.5mpg consistently in town commuting to work.

I will report again when I've used up a tank or two with the clutch fan re-installed.

(Just a side note, the grocery-getter '00 Contour with the 4 and an automatic gets about 23 in town)

 

[aldive]

Why did you remove the e fan?

 

[Texan01]

My particular e-fan is undersized and in 95+ degree weather will cause the A/C to cut out due to excessive high pressure at idle/slow speed driving (less than 30mph).

Not fun when you are transporting co-workers to lunch and the A/C quits for no apparent reason and then starts back up.

At 100 degrees with the A/C on it will also cause the engine to run hot enough for the computer to attempt to cool the engine off by increasing idle speed from 750 to about 2000 rpm.

With the A/C off or weather below 90, the e-fan will keep the engine operating right in the middle of the gauge in all weather.

 

[atistang]

My particular e-fan is undersized and in 95+ degree weather will cause the A/C to cut out due to excessive high pressure at idle/slow speed driving (less than 30mph).

Not fun when you are transporting co-workers to lunch and the A/C quits for no apparent reason and then starts back up.

At 100 degrees with the A/C on it will also cause the engine to run hot enough for the computer to attempt to cool the engine off by increasing idle speed from 750 to about 2000 rpm.

With the A/C off or weather below 90, the e-fan will keep the engine operating right in the middle of the gauge in all weather.

what kind of fan are you using?