Electric Cooling Fan
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William Davies, 26-Feb-2005, 12:48pm on TSSC
The benefits of the electric cooling fan are also debateable. The usual 13/60 fan is a very light aluminium pressing. While there is an argument that the standard fan is using energy even when not required, this is traded against the electro-mechanical losses of an electric fan. Here the energy is converted from mechanical to electrical at the alternator/dynamo, then converted back to a mechanical action by the fan motor. I don't know which is truly less efficient but I'm sure someone will have done the maths. If you go for an electric fan be sure to have the full width 21" radiator in place first as the fan body will obscure a large proportion of the standard 14" radiator.

Chris Taylor, 02-Mar-2005, 06:45pm on TSSC
Interesting to see how themes crop ug again and again. The old chestnut about overall efficiencies of engine to alternator to fan motor versus direct drive is a complete red herring. The power "saving" (and it's absolutely real; why do virtually all current cars have electric fans, and the rest have viscous couplings which do a similar job?) is not because the mechanical fan is inefficient and the electrical one more efficient, but simply because the mechanical fan is being powered ALL the time.
The drain on the engine increases with engine speed (it's doing more work by pumping more air) so the direct drive fan is not really well matched to its task. It barely passes enough air for cooling at tickover, but pumps far more air than needed at high speed, and it pumps air whether the cooling is needed or not. A viscous coupled fan is better, but the thermostatic electric fan is better still as it runs at high speed and pumps effectively when it does, but only runs when cooling air is actually needed. The only down side is that of shielding some of the radiator core from natural air flow as mentioned by some above. I ran my Herald for some time with no fan at all and never had any overheating at speed, only a bit warm in traffic. Fitting "shields" each side of the radiator to "funnel" air through all the radiator rather than round it (like on the Spitfire) was an improvement.
Although arguably if an electric fan cut in when you were accelerating hard, you would not get any more power at that point in time, you get the benefit in fuel economy much more of the time, as well as the extra 3bhp at higher revs for MOST of the time

"Where do most after market electric fans fit on Triumphs?"

Canley Classics about electric fans:

Smack bang in front of the radiator core masking anything up to 30/40% of the core, look how big that motor is, and how much area the fan blades mask when both stationary and when rotating, even the mounting brackets mask parts of the core. If you can't get the fan on the engine side of the radiator sucking warm air through it then take it off and throw it in the bin.

Even we sometimes don't listen to our own advice and quickly learn the lessons all over again.

Many years ago I built John Kipping a Herald that became known universally as the Rally car. It was built initially to recreate the 1959 Trans African Herald prototype proving run immortalised in 'Turn left for Tangiers'.

Built with 1500 running gear and a full width radiator I made the mistake of fitting an electric fan ignoring our own advice. Anyway John and myself set off on the long slog down through Europe to Gibraltar to catch the ferry across to Morocco. As we crossed through Spain and things warmed up it became apparent that engine temperature seemed to be increasingly controlled by the fan cutting in, a worrying sign as we would be crossing the Shara desert in a few days time! Things came to a head in the Atlas Mountains in the Shara, on the climb the fan was working continuously barely stopping us from boiling over, and then to cap it all we lost all the water from the radiator. The fan was of the type that bolts directly through the core and one of those mountings had worn through a tube. The hole was fixed with Araldite (wonderful stuff should be in everyone's toolkit), all our drinking water was put in the radiator, and the fan was thrown at a passing camel!

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