Viscous vs Elec fan

There was a thread on this recently. ISTR that the view was, if it's working why replace it? There is very little additional benefit from an electric fan.

Cheers

Peter

puffernutter uttered summat worrerz funny about:

Yup I found no difference, Just quieter running. Other than that a waste of my time.

Lee D

Do a search for recent articles, this has been discussed at length on various occasions. My personal opinion as an engine builder is that electrical fans promote thermal instability (constant cycling) within the cooling system, something definitely to be avoided with a V8, more so with the 3.9 and larger due to block issues, and are next to useless compared to a properly working viscous setup. The fuel savings are so immeasurable as to be non-existant.

1. A viscous fan only draws power from the engine when it is required to lock up and cool. At other times, it consumes virtually no energy.
2. It is a direct mechanical drive with very little energy loss, only a miniscule ammount is lost to heat.
3. An electric fan has at least 2 energy conversions, mechanical to electric to mechanical, with heat losses at each conversion stage.
4. The electric is less reliable, I know of more motor failures than viscous coupling failures. Just my tuppenceworth. Badger.

On or around Tue, 29 Nov 2005 13:10:12 +0000 (UTC), "Badger" enlightened us thusly:

I'll add my pennorth here an' all.

on the 110, when I put the original V8 in, it was a P5B engine with a well-bent fan, and since I had a leccy fan anyway, I kept it. One hot day the leccy fan motor gave up and siezed.

after that, I looked around in the shed and found a fixed fan to bolt on the engine. Very littel to go wrong, and the only thing it does is waste a small amount of power spinning when it doesn't need to.

Viscous fan should psin for the first 30 sec or so, (you will hear it at moderate revs) and then spin down to idle unless it gets too hot. Provided it works, it's very effcetive, and they seem to fail most often into "stuck on" mode, which is a bit noisier and less efficient but at least doesn't overheat the engine.

I agree with all the above, plus the 3.9 on V8's have some *really* scary temperatures in the spark plug "holes", which an electric fan will not cool when not running, leading to spark plug & lead problems. (Source - project at Rists (lead makers) when working there)

Richard