viscous-vs-electric fans

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5th October 2009, 01:03 AM
LOVEMYRANGIE

Quote:

Originally Posted by Psimpson7

I'd go viscous every time. They move massivley more air that an equivalent sized electric one.

Not necessarily. The problems with mechanical fans is they rely on engine speed. Slow running, low engine speed means low fan speed. I havent had one issue with overheating in the 4 years they have been on. Crawling in peak hour traffic with twin thermos running pumps a lot more air than in idling engine fan I'm afraid.
The mistake everyone makes is bad fan selection. Davies Craig fans are absolute rubbish and performance wise are very poor indeed. A lot of people have had success with the Falcon fans but I custom made mine using 13" SPAL fans. Each fan pulls 2000+ cu.ft/m thru a 40mm core.

I can stand on the loud pedal with the A/C on and it actually gets up and goes and stays nice and cold inside!!!
Nope, I like my thermos, never look back.

Cheers

Andrew.
5th October 2009, 08:14 AM
350RRC

Quote:

Originally Posted by LOVEMYRANGIE

Not necessarily. The problems with mechanical fans is they rely on engine speed. Slow running, low engine speed means low fan speed. I havent had one issue with overheating in the 4 years they have been on. Crawling in peak hour traffic with twin thermos running pumps a lot more air than in idling engine fan I'm afraid.
The mistake everyone makes is bad fan selection. Davies Craig fans are absolute rubbish and performance wise are very poor indeed. A lot of people have had success with the Falcon fans but I custom made mine using 13" SPAL fans. Each fan pulls 2000+ cu.ft/m thru a 40mm core.

Agree totally with this ^^^^^^. Low speed crawling with twin thermos has it all over a single engine driven fan. At highway speeds the pros and cons of either set up becomes largely irrelevant.

Have no idea what the ELs flow on mine, but its truckloads more than the original fan on the water pump. At idle there is absolutely no comparison.

The efficiency of the shrouding comes into play as well. Two fans are directly pulling air through a more widely spread and 'larger' area of the radiator, instead of a smaller area in the centre.

Flame away. :D

cheers, DL
5th October 2009, 04:59 PM
Dougal

Quote:

Originally Posted by LOVEMYRANGIE

Not necessarily. The problems with mechanical fans is they rely on engine speed. Slow running, low engine speed means low fan speed. I havent had one issue with overheating in the 4 years they have been on. Crawling in peak hour traffic with twin thermos running pumps a lot more air than in idling engine fan I'm afraid.
The mistake everyone makes is bad fan selection. Davies Craig fans are absolute rubbish and performance wise are very poor indeed. A lot of people have had success with the Falcon fans but I custom made mine using 13" SPAL fans. Each fan pulls 2000+ cu.ft/m thru a 40mm core.

I can stand on the loud pedal with the A/C on and it actually gets up and goes and stays nice and cold inside!!!
Nope, I like my thermos, never look back.

Cheers

Andrew.

I agree with this too.
The "generic aftermarket fans" are crap. Especially the "multi-fit, can push or pull no shroud needed" types.

I run two corona fans with integral shrounds on my rangie radiator and they fit excellently. Only a small extension to the shrouds around the side was necessary to keep the air moving in the right direction.
Of course with a nice efficient diesel they don't run much. But when needed they shift a lot of air regardless of engine speed.
7th October 2009, 05:20 PM
streaky

Quote:

Originally Posted by Yorkshire_Jon

This old chestnut of a question will never go away - opinion is simply too greatly divided!!

Personally, I would (and do) always go viscous. Much more reliable and the viscous bit is fixable with a pair of the mrs' tights if need be!

I know the physics behind the increase power useage of viscous - but in reality its negligable on a 2.5t brick on wheels!

Viscous all the way!!

Jon

Hi Jon.

I agree with your choice of viscous fan and was able to add a bit of data to this debate a few weeks ago when we had my Discovery on a rolling road Dyno.
The Viscous fan stole 15hp from the wheels when it kicked in. I was quite surprsied...but I won't be changing it for an electric one either.

S
8th October 2009, 11:02 PM
LOVEMYRANGIE

Funny thing is, viscous fan some love, but viscous transfer, they hate.....;)

For those of you that love the fan, I have a spare for sale :D

Message - AULRO Classifieds

Cheers

Andrew.
8th October 2009, 11:16 PM
d2dave

Quote:

Originally Posted by LandyAndy

The only real advantage with the electric fans is you can easily make sure they are off for a water crossing and they wont destroy a radiator with the fan corkscrewing into it.
I prefer the viscous hub.
Andrew

This post has reminded me of something that I have pondered for years.

When doing deep river crossings it is advisable to remove fan belt.

I have often thought of making some thing to lock the fan from turning but I am not sure whether this would do any damage to the viscous hub.

Does anyone know?

Dave.
9th October 2009, 09:26 AM
mike 90 RR

Quote:

Originally Posted by Mr Whippy

When doing deep river crossings it is advisable to remove fan belt.

This is not a Hot idea as you also stop the coolant flow, moving around the block & heads

Quote:

Originally Posted by Mr Whippy

I have often thought of making some thing to lock the fan from turning but I am not sure whether this would do any damage to the viscous hub.

This is also not a Hot idea ... cause if the Temp rises while on dry ground ... then the viscous will "lock up" while "being locked up"

If you want to stop the fan for a water crossing ... Remove it, before crossing

Mike
:)
9th October 2009, 10:06 AM
LOVEMYRANGIE

Quote:

Originally Posted by mike 90 RR

This is not a Hot idea as you also stop the coolant flow, moving around the block & heads

This is also not a Hot idea ... cause if the Temp rises while on dry ground ... then the viscous will "lock up" while "being locked up"

If you want to stop the fan for a water crossing ... Remove it, before crossing

Mike
:)

Or use thermo fans with a lockout switch..... :cool:
9th October 2009, 10:08 AM
Dougal

Quote:

Originally Posted by LOVEMYRANGIE

Or use thermo fans with a lockout switch..... :cool:

Electric fans aren't going to eat the radiator anyway. No need for a lockout switch IMO.
9th October 2009, 12:27 PM
mike 90 RR

Quote:

Originally Posted by Dougal

Electric fans aren't going to eat the radiator anyway. No need for a lockout switch IMO.

... You want the "lock out switch" to prevent them coming on, if water shorts out the relays (or what ever) when crossing / water splashing about the engine bay ...

You don't want em to turn on, when submerged and pulling water /// (Pull the main fuse prior, would be the go)

Mike
:)

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