Electric Fan worth it?

Joined
Aug 3, 2014
Messages
44
I've searched this forum and found almost no discussion about replacing the manual fan with an electric one. I've made this mod on almost every classic car I've ever owned and feel that it helps reduce drain on the engine. I'm not looking for massive power gains, but I know it would help in some ways.

I'm also not a guy who tries to fix something that isn't broken, so I'm open to the opinions of the purists out there, but I want to know if anyone has done this mod, their experience with it, and what fan size they choose.
 
Joined
Nov 26, 2015
Messages
200
Location
San Diego, California
Our fan is a little over 18.5" in diameter, so slightly bigger than theirs.
Our RPM range is the same for 1FZ guys (5500 rpm), 3FE doesn't have quite go as high.
We have larger clearance to the fan shroud so ours is again worse. (completely open makes it draw more hp, having less precise shrouding makes it more "open")
So about 15 or more horsepower when the clutch IS NOT engaged. With the clutch engaged, probably way worse.
The plastic flex fan (so no clutch) dropped 23 hp. Ours is probably worse than that engaged because it's not a flex fan.

That said, an electric fan simply can't dream of competing with a 15 horsepower fan. It's just straight up incomparable. you're talking a 1 hp (at most) electric, and even with better, tighter shrouding, you just can't beat having literally 15-25 times more power to it.
 
Joined
Sep 30, 2014
Messages
573
Electric fans CAN work really well, however the vast majority of people who have done it have done it incorrectly.

Firstly, bolting a fan or two directly to the radiator won’t work. It needs to have a shroud... secondly, I recommend finding a suitable sized shroud from an existing vehicle as it’ll be designed properly.

now I’m not sure if this will fit the 80 series radiator but I have used a Mercedes W203 electric fan on conversions before. At max power it will pull just over 50 amps and moves a serious amount of air. (In fact I would say it moves MORE air than the mechanical fan at lower RPM, which makes it ideal for sand driving etc).

the downsides/things you need to considered is your electrical system needs to be up to scratch, and some of the later model fans require a PWM controller to control the speed. The upside to that is you can set the fan for a % of power based on temp. Eg for every 1 degree increase in temp above say 70c increase fan speed by 3%.

it is a fair amount of work, but done properly can offer better cooling, better sound and be even more reliable than the mechanical primarily as you can turn it off easily for water crossings.

that said, a well maintained mechanical fan is pretty bulletproof, and if you’re having overheating issues a new fan won’t solve that, you need to fix the underlying cause.

the main reason for swapping to an electric fan is quieter operation during normal driving, faster engine warm up, better performance in sand and the ability to switch off the fans during water crossings. EDIT and if used in conjunction with an electric booster water pump, it means in the event of overheating or hot temperatures you can keep the thermofan running after the engine is switched off while still circulating coolant. This is by far the biggest advantage, but again requires you have a good alternator, battery and wiring.

just don’t think you can buy a Spal fan, whack it on and expect good results.

Edit: here is a quick video to give you an idea of the amount of air it moves. (And even this video doesn’t do it justice).

 
Last edited:
Joined
Sep 30, 2014
Messages
573
That said, an electric fan simply can't dream of competing with a 15 horsepower fan. It's just straight up incomparable. you're talking a 1 hp (at most) electric, and even with better, tighter shrouding, you just can't beat having literally 15-25 times more power to it.

I do slightly disagree, the main problem with mechanical fans is the gap between the shroud and blade needs to be large (as the engine moves around a lot) which kills efficiency. An electric fan “seals” really well meaning it makes use of its power draw much more efficiently.

And as above, the mechanical fan is based on engine rpm, not on heat load. So if you do start to overheat and drop to idle, your airflow drops a lot. Likewise if you turn your engine off that stops airflow entirely. Additionally an electric thermofan can be set to higher rpm when you switch the aircon on, whereas a mechanical fan doesn’t really help if engine temps are under control.

So again it’s one of those things where if done properly, an electric fan can be really good. However it requires a lot of cost and effort... too many people have tried the cheap/easy path then been disappointed by the results.
 
Joined
Nov 26, 2015
Messages
200
Location
San Diego, California
I do slightly disagree, the main problem with mechanical fans is the gap between the shroud and blade needs to be large (as the engine moves around a lot) which kills efficiency. An electric fan “seals” really well meaning it makes use of its power draw much more efficiently.

And as above, the mechanical fan is based on engine rpm, not on heat load. So if you do start to overheat and drop to idle, your airflow drops a lot. Likewise if you turn your engine off that stops airflow entirely. Additionally an electric thermofan can be set to higher rpm when you switch the aircon on, whereas a mechanical fan doesn’t really help if engine temps are under control.

So again it’s one of those things where if done properly, an electric fan can be really good. However it requires a lot of cost and effort... too many people have tried the cheap/easy path then been disappointed by the results.
I agree wholeheartedly on the efficiency, but I don't think it can be so much more efficient that an electric could ever dream of matching a mechanical fan. The electric ring-style fans are typically 50% efficient in optimal conditions, so poor shrouding losses for the mechanical would have to put it at maybe 3% efficient to be beaten. I feel like there is no way it is that bad even with a 1" gap all the way around, not with the sheer volume of air I can feel blowing out even at idle.
ShieldSquare Captcha - https://iopscience.iop.org/article/10.1088/1757-899X/52/4/042008/pdf - these guys got another 5% out of a typical ring style fan by addition of an anti-recirculation ring.

Your second point raises driving style and people doing it wrong. When things get hot, you need to drop gears and rev the heck out of it, not "give it a break". Not exactly intuitive I guess. At high RPM, you have more than enough cooling airflow for continuous full throttle usage in hot weather, far hotter than Toyota's 104F/40C maximum, even with little to no ram air affect. Of course, that's hard to do when crawling around through difficult obstacles, so that's a plus to the electric fan.

Overall I like the idea of the electric fan because more horsepower (duh), better fuel economy, and realistically you don't need that much cooling unless you're working it hard when it's really hot out. That said, to get something that would compete with the mechanical fan for really hot weather in SoCal desert mountains would be expensive I think. What would make me most comfortable for the occasional extreme environment use is dual front high mounted electric fans with a shroud (yeah I know, a front shroud reduces ram air for freeway use, but with dual fans you've still got most of it uncovered and the covered part is behind the bumper anyways), while the engine would get a flex fan mounted to something like an AC compressor clutch so it could completely disengage. Then you get the best of both worlds.

IIRC from the wit's end turbo thread dyno results, stock only gets 130-140hp at the wheels, so that 5hp at 3500rpm to 9hp at 4500rpm is definitely enough to be felt (about 3-7%). But you'd probably get just as much gain by going from 15w-40 to 5w-30 oil, (that's not something I'd risk, I like my rod bearings how they are).

I don't think you'd be able to feel a gain at normal cruising RPMs though, it was down to 4hp at 3k rpm and it just keeps going down from there.

Edit: Or alternatively, if I put on a cooling fan like that video and it handled a towing a 5000lb trailer up the grades (creating a situation for full throttle without a lot of vehicle speed) on a 110F day in desert valley I would be totally comfortable from that point on. I haven't had an opportunity to test it out like that, but the stock system should handle that no problem if you let it sit at 3.5-4k rpm the whole time.
1627347466699.png
 
Last edited:
Joined
Aug 3, 2014
Messages
44
Thanks for the replies guys. For now, I'll stick with my original fan as it still works great. I hate to mess up a good thing. But if I ever decide to replace it with an electric fan, I wouldn't want to go the cheap/easy route.
 

baldilocks

Battle Ground, WA
GOLD Star
Joined
Jan 29, 2014
Messages
7,371
Location
Battle Ground
I've searched this forum and found almost no discussion about replacing the manual fan with an electric one. I've made this mod on almost every classic car I've ever owned and feel that it helps reduce drain on the engine. I'm not looking for massive power gains, but I know it would help in some ways.

I'm also not a guy who tries to fix something that isn't broken, so I'm open to the opinions of the purists out there, but I want to know if anyone has done this mod, their experience with it, and what fan size they choose.
The 80 is like farm equipment not race cars. That’s why you couldn’t find any tall tails of how electric fans out performed the engine driven fan. Besides that, electric fans make a lot of noise.
 
Joined
Dec 24, 2019
Messages
355
Location
Sydney, Australia
Don't forget that just because fans are electric doesn't mean they don't drain HP. Electric means more load on the alternator, and the alternator itself is being driven by the engine and will steal more HP the higher the load. For people who are running a lot of accessories, the extra power draw from the fans might also be an issue. Being able to turn them off for water crossings is about the only benefit I see, but that's traded off by the risk of shorting/damaging the fans on those water crossings due to water intrusion IMO. All in all, I'd go stock mechanical always. The stock cooling system is good enough for these rigs. If you're overheating, there's a problem somewhere you need to address.
 

mudgudgeon

SILVER Star
Joined
Dec 17, 2007
Messages
5,144
Location
Across the pond, and upside down
I contemplated electric fans for my turbo diesel 80.
Mainly thinking it would free up a few ponies.
I'm off the view that in a marginally powered vehicle, any load you can remove from the engine is worth while looking at. It's kind of free horse power.

I had a set of Ford AU Falcon fans. They are twin fans in an OEM shroud. The same fans and shroud was used in a USA Tuarus (late 90's, early 2000's)
They are a good size match for the 80 radiator, and regarded as having a good output. AU Falcon has a 4.0 I6 in a full size sedan.

I never installed them.
Cooling was slightly marginal in my rig, and I opted to improve the OEM engine fan by testing and adjusting the thermal/ viscous clutch, and upgrading the silicone oil

Its hard to beat the engine fan with upgraded OEM fan clutch hub
 

Zjohnsonua

SILVER Star
Joined
Feb 1, 2018
Messages
1,440
Location
Huntsville, Alabama
There is no free power. The power used to drive the mechanical fan is less than that used to pull the electrics...there are efficiency losses in moving back and forth from mechanical to electrical energy. Electric just applies that load in a more efficient manner by only running when heat extraction is needed.

Avoid SPAL. They're LOUD, and don't move as much air as the OE units from Merc or the Taurus/Contour units. The OE units are hungry - lots of threads in here on them. Budget for 60A to drive them at full power. The 80 needs a new alternator to drive that load...you only have an 80A unit and it is already feeding the rest of the loads on your truck.
 
Joined
Sep 30, 2014
Messages
573
Actually the power to drive a mechanical fan is substantially more than to drive an electric fan (even with the losses of the alternator etc).
A mechanical fan can sap as much as 35hp (26kw). Even a 60amp fan is only drawing 720w or about 1hp.
So even with some efficiency losses you’re still only looking at a max of 1.2hp for electric vs 35hp for mechanical.

the biggest issues with mechanical fans is the shroud gap is large meaning very poor efficiency, plus the fan can only spin as fast as the engine... whereas an electric fan runs based on heat load.

as above though, “cheap” electric fans just won’t work. You can do it properly but it takes a lot of work and can be expensive.

I still maintain that if you do it properly (eg big alternator, high quality wiring, high powered electric fan, electric booster pump, proper designed shroud with a high quality radiator), electric fans can be better than mechanical. The thing is, mechanical is very simple and hard to screw up. Electric is complex and hard to get working well.
 
Joined
Nov 26, 2015
Messages
200
Location
San Diego, California
I put in an electric fan with shroud from a taruas I think, really high cfm. Into my old 1984 4runner, no gains were noticed.
None at all? It would only become potentially detectable at around 3500 rpm, but I would've thought it would be noticeable up at redline.
Especially on a lower powered vehicle like that.
Assuming the electric fan is on a thermo switch and normally turned off of course.
 
Joined
Aug 5, 2020
Messages
13
Location
UK
Fitting a CVT to a viscous fan clutch might help increase low engine speed cooling performance if such a thing exists?
 
Joined
Sep 30, 2014
Messages
573
A viscous fan clutch is effectively a CVT...

it just can’t “gear up”, meaning the fan can’t exceed engine speed
 
Joined
Aug 5, 2020
Messages
13
Location
UK
Or even variable pitch fan blades that can adjust automatically according to cooling demand and the ability to feather and disengage the fan at highway speeds.
 

Users who are viewing this thread

Top Bottom