Is there any proof that E-fans improve gas mileage,hp over clutch fans?

 

I doubt there is any real proof since you'd have to measure horsepower under actual driving conditions with wind blowing through the radiator and at different speeds and driving conditions. Any real benefit would likely come due to the electric fan being off when the coolant temperature is low. But, that's negated with A/C since on all I've ever seen the fan is on constantly when the A/C is on. And, when the fan runs the alternator has to pick up the added electrical load thus using more HP. Unless the temperature is high enough to put the clutch in direct drive mode it essentially freewheels above about 35 or 40 mph. But electric fans are good for vehicles with transversly mounted engines becaus no complicated ducting or belt routing is required.

 

I believe it would be an advantage if you did a lot of highway driving, where you do not need a fan, and the natural airflow is enough to cool the engine. If you do a lot of city driving, I see no advantage.

 

I don't know about performance, but I have seen positive proof that electric fans look cool under the hood.

 

I haven't measured actual performance, but can tell you there's a noticible seat-of-the pants difference. I have pretty carefully measured my mileage and have gained 2-3 mpg with the electric fan.

 

Some number of years ago, Hot Rod magazine did an article on that question. It turned out that electric fans caused more of a horsepower loss due to the alternator having to make more electricity to drive the fan. The best setup for horsepower was a hydrostatic clutch fan. And the stock fan and a fan shroud flow more air then an electric fan which concentrates all of its flow through only part of the radiator, the part that the fan is covering.

 

Interesting....I'd like to see that article. It sounds like they used non-shrouded fan(s) and a stock alternator, neither of which are very efficient. I used a shrouded fan from a Town Car (a peferct fit for the V8 radiator with very little mod) and did the 200 amp 3G alternator upgrade as part of the same project. The 3G produces much more power at the same RPM, so the load wouldn't increase. Maybe that's why my experience is different.

 

After some google searching I found some sites with dyno figures that indicate there may be a HP gain by using electric fans. I did find another consideration that seemed to make sense. An electric fan draws the same amount of air regardless of engine rpm. A belt driven fan will only draw what the rpm of the engine makes it. Also, I would definately use factory fans. The Mark VIII fan is impressive and flows a ton more air then aftermarket fans. It is also far more reliable. I have had several electric aftermarket fans fail. The mark VIII fan and shroud does indeed cover the entire radiator. This is very important. BTW I have a Mark VIII and it cools just fine.

Another advantage of an electric fan for off road guys is that you can turn it off for the occasional mud hole. When on trail rides we turn off the fan before blasting through the muddy hole. It helps to prevent throwing as much muddy water on the engine.

The only consideration left is how much to spend. A new Mark VIII fan can be bought for $278. A new fan clutch and fan are about $100. You have to decide how much to spend.

 

Or, $20 from a local U Pull It.

That's what I'm going to do.

 

Depends on the electronics you have running the fans. Until the engine gets to the point that it needs cooling an electric fan may be completely off and drawing no current and not putting any load on the engine at all.

Here's how I see it:

Electric Fan benefits:

High load low speed, (maybe towing uphill in stop/go traffic) an electric fan can pull more air than an engine fan because it can run at a constant high speed, not dependent on engine rpm.

A lot less load on the water pump bearings so they should last longer.

When the engine isn't up to temp it might not be using any power at all.

Ability to turn off (aforementioned water crossings)

Somewhat easier access to the front engine accessories and easier belt changes.

Usually better design fan blades resulting in more airflow/input power and quieter operation. Let's face it, the early fans were just crudely bent, usually flat, pieces of steel and were more air paddles than fan blades.

Electric Fan Drawbacks:

Bigger alternator needed. (Specs on the fans I got said 28 Amps Max draw)

Possible reliability problems, although I have seen plenty of problems with clutch fans too.

Price and installation costs (if you can't DIY)


I swapped the engine driven fan on my Falcon about 7 years ago for a twin fan setup from a later model and have had no reliability problems. The main reason I did this is that the engine driven fan would stir up a lot of dust and leaves that would end up in the air cleaner or stuck between the aircon condensor and the radiator. Haven't had that problem since. For about a week after I installed them I was just using a switch to turn them on (hadn't set up the automatic controller yet). I also had a dash mounted LED to indicate when the fans were on. At highway speed, with the fans turned off, the LED would still glow as the airflow was turning the fans and making them act like DC generators. My theory is, that even if your electric fans were turned on at highway speeds then they would be making very little, if any drag on the electronics.

 

Here's how I wired mine...

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I used the first diagram with some minor mods. Mine also turns on with the A/C as well as by temprature, and I added an indicator light. I used a 75 amp relay instead of a 30 for the main power to the fan. I also used a GM (God help me) fan switch to control the fan on/off temperature range. Mine turns on at 204 degrees and off at about 190. It threaded right into the stock temperature sensor orfice on the intake manifold. I moved the temperature sensor to the plug on the thermostat housing where it also threaded right in.

I got the fan for $40 shipped on Ebay, and at the same time picked up a new OEM radiator for $60 shipped on Ebay. I was doing the alternator upgrade anyway because I added dual subs, converted the headlights to a relay system, and added a couple of other electronic goodies. It cost about $300 total for that upgrade, but the 200 amp unit in there now will power everything in the truck, power pretty much every house in the neighborhood, and still have enough juice left over to execute somebody.

All told, for the tune of about $500 the truck now has 21st century electronics capability, gained power, saved wear on the front of the engine, and with the 2-3 MPG I gained will pay for itself by next week with gas at $4 per gallon......