Electric fan fuel savings?

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meep

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Hello,

I'm contemplating converting my jeep to an electric cooling fan for improved mpg. My lowest in-town mileage has been 18, highest 20.5. I absolutely love this old beater (234,000 miles and counting) but I do feel bad about the crummy mpg/emissions and am willing to invest here and there to help efficiency.

The A/C is kaput, so I only need about 2000 cfm (A/C works then you need 3000). That puts me in the $70-80 fan range, plus ~30 for a thermostat (purchased or homegrown).

The question is, I've *read* that these show a mpg improvement, but a lot of folks just parot the marketing literature. I'd like to know if anyone has actually experienced an improvement after trying it themselves.

Mike!
 
The M42 engine BMW folks do this commonly and show dyno improvements (which ought to relate to MPG improvekments if driven for economy and not power). That said, be sure to invest the $$$ in a good fan setup. Reliability can be an issue.

JMH
 
Reliability--- Question then, are there brands to avoid? Sensor types to avoid?

While spending $100 on a "luxury" upgrade (i.e., not critical for daily use) I can do, the $300 fan kits ... um, just too much.

Mike!
 
I have an 03 Ford Ranger pickup. I'm a member of 4 Ranger forums and the discussion on those forums by people who've made the switch is that switching to an electric fan will give you little if any mpg, torque, or hp improvement.
 
Originally Posted By: meep
Reliability--- Question then, are there brands to avoid? Sensor types to avoid?

While spending $100 on a "luxury" upgrade (i.e., not critical for daily use) I can do, the $300 fan kits ... um, just too much.

Mike!


Id likely try to scavenge OEM parts, which may have a bit better reliability factor built in, compared to the pep boys special.

Ill ask at the M42 forum, and try to get an answer back for you...

JMH
 
I would do it with junkyard parts. Apparantly the Taurus V6 fan is the one to beat.

JC whitney has an adjustable sensor that stuffs in the radiator fins. I like this style because as the system heats up in traffic the rad gets warmer until everything is at engine thermostat temp; set the adjustable sensor for this or slightly below and the engine will never vary since there's always cooler coolant available in the rad.

You can and should also mount a toggle switch inside the cab as a backup or for testing.

I've had a few belt driven fans and can feel them sap power on cold starts until the clutch loosens up. As cold as it is up here I would rather go electric-- my electric fanned cars never turn the fans on 6 months out of the year.

Had a cherokee with BOTH electric and belt driven fans, nice compromise. If you have a wrangler etc with similar radiator the cherokee may be a place to look for parts.

Also consider old benz diesels used to have front mounted pusher fans, if you do two fans you'll have supreme reliability.
 
I've seen the taurus fans come up before. The internet junkyards want as much for a Taurus fan as AA wants for a brand new perma-cool.

Internet stories are sketchy. Fellow in a dakota saw ~.75 mpg increase avg. with before/after #s on the same highway route. Tacoma Prerunner from 16-21 to 18-24, but that also included an exhaust makeover. Some folks report no difference. Some say it depends on your climate. I'm in No. AL... it gets pretty hot here.

M
 
Originally Posted By: eljefino

Also consider old benz diesels used to have front mounted pusher fans, if you do two fans you'll have supreme reliability.


despite the reliability of older benzes, I wouldnt call this fan the best. It is noisy when on low speed, let alone high speed. THey do sieze up after 20 years, and they dont seem very repairable. Plus, for the price, I dont think they move a LOT of air...

THen again, maybe thats exactly what is needed...

JMH
 
Yes, though I suspect a flexy would be roughly the same as my current temp-clutch setup.

Honestly, it doesn't seem like there's much real world evidence that an elec conversion helps mpg. That's really my question. I know roughly how to do it, know the aftermarket thermostats aren't quite as elegant as oem... but don't know if it will actually help.

Yes, it *should*- b/c a. it's not always spinning; b. isn't wasting some energy in the clucth, generating heat at the clutch; c. is able to work best at it's design rpm, as opposed to belt-driven that must work at variable speeds.

But, if my engine rpms are generally under 2200 unless a. towing b. climbing over the occassional curb/rock/whatever, then I may not be wasting enuf energy to matter.

I may just wait until the clutch tanks. I think it's on it's way. The fan spins a good 3-4 seconds after engine off.

Thanks for the thoughts!

Mike
 
The '89 to '95 Taurus SHO fan for the manual tranny which is also the Taurus/Sable 3.8L fan, are the best single fan out there.
 
Most light trucks sold in the USA have mechanical fans. Most cars switched over to electric fans since 1995 or so. Guess it's due to fuel economy requirements.
 
Originally Posted By: Warlord
From what I've seen you would never make up the cost of the conversion in saved gas.


Pls remember the original post is more for environmental consciousness than pure $ gain.

IF it yields .5 mpg increase...

A 0.5 mpg increase over 22 gals used would yield roughly 11 additional miles per fillup, which at $0.16 per mile (at $3/gal) gives $1.76 saved per fillup. 60 fillups pays for the fan. That's 18 months for me, which is a long time yes but within the timeframe I intend to keep the car. Takes less time if you're being forced to replace the $40 clutch anyway. Now, if it yields a full 1.0 mpg....

That said, my original question was whether or not there is any real world evidence that the electrics really save any fuel or if it's just mktg hype.

Thanks for the feedback... Frankly, I'm skeptical since the only real-world data we have that was relayed from the Ranger forum says, "well, not really," I'm not jumping up and down to go do this. Oh well...

Mike
 
Originally Posted By: brianl703
Most light trucks sold in the USA have mechanical fans. Most cars switched over to electric fans since 1995 or so. Guess it's due to fuel economy requirements.


most cars since 1995 have been front wheel drive, making mechanical fans difficult.
 
Originally Posted By: sprintman
Who sells a vehicle without electric fan? My 89 mazda has two. None of the other vehicles in the work car park have anything but electric fans.


My '96 Audi has a viscous clutch driven fan. There is an electric auxiliary fan that runs when the A/C is on or if the main fan can't manage. Many folks have replaced the viscous clutch fan with an electric one. The power to drive the electric fan comes in the end from the engine, too. I don't know if an an electric fan is more efficient, but none of the folks who installed one claimed better gas mileage.
21.gif


An advantage of an electric fan would be the lack of parasitic drag when accelerating momentarily. Once the alternator starts laboring the advantage may well shrink.

Following the KISS principle, I prefer simple mechanical devices over simple electric devices. Viscous clutch driven fans are very reliable and usually for a very long time.
 
Originally Posted By: tom slick

most cars since 1995 have been front wheel drive, making mechanical fans difficult.


The RWD ones mostly use electric fans since 1995 or so.
 
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