Well, the only caveat I'd add is that the fan isn't really robbing you of power (or subtracting from gas mileage) when you're going down the highway. The clutch disengages past a certain RPM and engine temp, so the cooling is being done by incoming air, not from the fan. As far as getting all of the gains . . . you spent several thousand $'s in order to gain 3mpg on the highway. Even if we call your total gain 3mpg, and you drive 10K miles per year, you save $325.65 per year. So assuming you spent $3K for all of your mods, you will break-even in 9 more years from the increased fuel mileage . . . not exactly what I'd consider to be a good reason to do the mods.

As you said, it DOES wake up the 5.4L a bit, but I wouldn't be using increased MPG's as a reason to do any of it, simply because the increased MPG's don't pay for themselves for almost a decade after you do them.

 

Sounds like you, like most people should leave yours stock. To me everything the factory does is a compromise and can be improved. Like the under drive pulleys-there is power and efficiency to be had by slowing the speed of the accessories, but the factory has to assume that someone will want to leave it idling at 110 degrees with the A/C on full blast for an hour. Someone like me who won't do that can slow the accessories and get the efficiency 100% of the time, instead of over driving the accessories 100% of the time for that <1% event.

My whole kit was closer to $1500, and the mileage improvements I was quoting were all on the highway. Every time you step on the gas you have to spool up that 40# of deadweight whether the fan's engaged or not. Every time you want to pass someone, it shifts out of overdrive on a hill, you slow for a reduced speed limit and then speed back up. It adds up, to 1 MPG in my case.

So the payback is closer to 5 years, and I keep vehicles longer than that. And every time I drive it I am pleased, so to me that's a win-win.

 

There's no free lunch. You either spin up a mechanical fan (which weighs no where near 40lbs), or you make the alternator harder to spin because it has to power electric fans. I didn't disagree that there aren't things to tinker with or improve on a stock vehicle, my point is simply that it doesn't work out to claim savings on MPG's when the improvements have such a long payback. Driving the AC compressor slower, or the alternator, only results in reduced performance. Most people would rather have the A/C working well while sitting in traffic on that 110-degree day, then worrying about if their truck shifts out of overdrive on a hill. If you are comfortable with the reduction in accessory performance, that's great.

 

Actually, the only thing noticed is the increase in engine performance 100% of the time. Accessories have worked perfectly. The fan may not quite weigh 40#, but I was amazed at how heavy it and the clutch were. It is almost a two man job to lift it out while leaning over the grille! The alternator doesn't have any extra load on it the 95% of the time that the fans are off. That's where the gain comes in. When no cooling is required the electric fans are not costing you anything, but the anchor of a fan/clutch assembly still has to be spooled up every time RPM's increase.

 

What Spal controller did you use? the PWM? My only concern is can it handle the MKVIII fan. And it's a two speed single fan.

 

E-fan is a win win even Ford engineers are doing it, take a look at all the F-150 from 2009 and newer, no more viscous fan.

On a hot Summer day with A/C and viscous fan kicked on you can feel the engine bogged down and lack of power.

If you are going with E-fan makes sure you get the something over 5000 CFM and a good controller to support it, or else you'll be over heated using inferior aftermarket junks.

 

2010 and newer had electric fans.

The lack of power when the A/C is running primarily comes from the compressor. If you drive a car with electric fans, you'll still notice this. Especially on a heavier vehicle with a smaller engine such as my 2008 Fusion 4-cyl that I had. Electric fans draw a lot of amps, which puts a higher load on the alternator and creates drag. And if your original alternator is less than 150 amps, it should also be upgraded which adds to the cost. My 135 amp unit wouldn't handle it well at idle with both fans blasting, headlights on, and stereo bumping. I've been keeping an eye out for a Crown Vic police alternator at the local pick-n-pull, but they get yanked almost immediately when they hit the yard. But since they only charge around $30, I'll be patient.

2009 vs. 2010 fuel economy ratings on my truck went from 14/19 to 15/19. So there is some efficiency to be had since this was the only real change.

I'm not saying that electric fans are useless, but the cost compared to the benefit of a retrofit doesn't add up for me unless I acquired the OE parts for cheap.

The biggest improvement that a person can do to improve their mileage is to improve their driving habits. I average around 16 in the city, and 20 on the highway. But I was able to hit 23 on the highway by keeping the speed at 65. This was without the A/C on since it was during cooler weather. With the A/C, I lose about 1 MPG.

 

Yes the PWM. I don't know about 2 speeds...I think you would just leave it on high speed and let the controller modulate the speed. Not really necessary to have two speeds with that.

 

I'll have to disagree with this statement. I've had an FK35 from DC Controls for about 5 years and had an issue with the fan last week. I contacted Brian from DC Controls to see what their lead time was on a controller and explained the problem. Over the course of many emails, I was able to figure out that it wasn't the controller at all, but a shoddy connection at the fan. He could have just sold me a controller, but he didn't and spent his time helping me out. That to me is exceptional customer service. Yes they're slow, but it's a one man operation making these things.

 

Yeah but secondary drag from the clutch fan is almost as big or bigger, not try to argue, my butt's dyno and others on various forum felt like they have gotten rid of a cow in the trunk without the fan.

BTW, although E-fan does require higher amperage, it's not a constant drag like clutch fan.
The technology in the charging system has been improved nowadays, it's only charge when the delta between the battery and the system is greater than a set voltage, this means it's not necessary loading down while the E-fan is on.

 

Well that's good news.. I've read a lot of bad reviews.. not for the product for his customer service, length of time, and very slow response if any...