Electric Fans - Is there really a power increase?

[smo0othride]

After reading this article about the myth of electric fans, I am skeptical if adding an electric fan is really any upgrade.The article is based on an RX-7 but I think the same concepts apply. Here are some excerpts from the article:

"What's important to note is that the fan is only used when the engine is idling, or the car is creeping along at low speed (less then 20 MPH)."

"There will be a horsepower gain for sure, on the order of 0.5 - 1HP. But remember that the electric power to run the fan must come from somewhere, and that somewhere is the alternator. Electric fans draw quite a lot of current. Most pull surges of 35A or more to start up, then run at 8A-10A. This puts extra load on the alternator. Ever pedaled a bicycle with a generator powered light? If so, then you will know that as the electrical load on a generator/alternator increases, the generator/alternator becomes harder to turn. Suddenly, all that "free" HP you just freed up is once again being used. This time, though, it is being used to turn the alternator. There is also an inefficiency in the whole system. We are converting mechanical energy, to electrical energy, to mechanical again to run the fan. This very inefficient, much less then just driving the fan directly via the mechanical energy of the rotating shaft. "

 

[ELVATO]

It's mostly rotational weight that is saved. Not sure if you've ever held a fan and clutch before, but it's rather heavy.

Also, the efan isn't on all the time. It really only comes on when you're standing still. Anything above 20-30 mph, the air forced through the radiator does the cooling, so you don't need the fan. The stock fan still does spin regardless of how cold the enogine is.

The AC is a lot cooler at lower speeds with efans because they spin at max RPM, where as the stock fan only spins at less than 1000 rpms in stock and go traffic.

From what I remember from having mine in, there is a difference in throttle response. I remember you could definately feel the "drag" come back when I reinstalled my stock fan back on. The reason I reinstalled my back on was because of how unreliable the fan controller was. I think the Expy was about to overheat twice. The controller finally took a crap, and stayed on all the time, so I had to switch back. Of course, the warranty had just finished when this all happened.

 

[DarrinBC]

Troyer Performance has a slick e-fan setup with a good contoller. Pricey, but you get what you pay for.

Darrin

 

[gjhanson2]

I've always been a skeptic of the electrics because I've seen what the fans on my buddies' trucks have done when they get wet. I'm always open to being proven wrong though. Are there any off-road worthy e-fans that laugh in the face of a little water?

 

[ELVATO]

OEM fans shouldn't have too much of a problem. The one I ran was a Mark VIII fan. I think I've seen them used on rock crawlers.

I know the Troyer one used to have problem with the fan controller and it burning out/melting connections. I think they might have fixed that. There are several people on F150online who are running "cheap" setups who have had them for years. I guess I was just unlucky with my controller. The fan itself, though, still works well.

 

[DarrinBC]

When I put e-fans on my 01 F150 I went and found a temp sensor, from a BMW if I remember correctly, that had the right threads and triggering temps that I was after. Then I built a relay box that would allow the fans to switch on and off properly with both input from that and from the AC compressor clutch.

Problem with that one was that it still kept working even at higher vehicle speeds. I watched it closely for the first couple of months and since that never seemed to cause a problem I left it in place and it's still working. I used cheap fans though and they vibrate a little.

Haven't yet done anything with the Expy. If I do then I think I might get a Mark VIII fan and try that route.

Darrin

 

[tonydiv]

I've always been a skeptic of the electrics because I've seen what the fans on my buddies' trucks have done when they get wet. I'm always open to being proven wrong though. Are there any off-road worthy e-fans that laugh in the face of a little water?

Actually getting wet was one of the original reasons that off roaders went to electric. When you hit deep water the stock fan bends and kills the radiator. Granted, that's not as much of an issue with modern plastic fans.

All the big fan manufacturers have completely sealed units that don't have any issues with moisture. I ran four 10" electrics on my Scout for 12 years of daily driving and off roading and never had an issue. Part of the secret to keeping controlers alive is to use additional relays to take the brunt of the load. I had 4 relays, one to each fan, and used the relay in the controller to activate them.

 

[smo0othride]

To me it seems like the electric fan mod has the potential to cause more problems then it is worth, but supposedly the 2010 expeditions come stock with an electric fan

 

[expy916]

If you do alot of highway driving, DO IT. There is a difference, but like ELVATO said, its unreliable if done wrong.

 

[tonydiv]

From the pictures, the Troyer kit just mounts the fans to the rediator. This isn't the best way to do it. In order to get the most efficient air flow, you need to have a shroud around the whole radiator to "funnel" air through it.
A big part of the reason that I'm doing it is because of the body lift. There is 3" of radiator that is outside of the shroud and a 3" gap at the bottom that allows the fan to pull air around the radiator instead of through it.

Perma Cool and Flex-a-lite have the best set up. Flex-a-lite also gives dyno results that show 17hp, 20ft/lb and a 2 - 3 mpg increase.

It's not cheap, but it is easy to do. This is what I'll be getting in the spring.

http://www.summitracing.com/parts/FLX-270