Electric fan: any recommendations?

#1
I'm thinking of replacing the noisy, power-sapping and finger-slicing mechanical radiator fan with an electric one. There are several brands available, including some surprisingly cheap ones which instinct tells me to avoid. Presumably the more of the radiator area covered by the fan, the better.

Has anyone fitted one to their four-cylinder P6? I'm hoping for a steer on fan make, type and size, and a suitable thermostatic controller so it operates automatically.

Thanks in advance for any ideas.

John
 

quattro

Administrator
Staff member
#2
I bought a cheap one, and it wasn't very good. When I got into a traffic jam on a very hot day, the temperature went up to 127C :oops:

I now have a Revotec fan and controller, excellent quality and keeps the temperature in check under any circumstances.
 
#5
There is a web page that tries to calculate what size radiator you need for a given engine size, usage and packaging. Makes interesting reading - What size radiator do I need for my car? - Super 7th Heaven
Using my interpretation of the pos and neg factors, a P6B manual should have a rad core of 280 cu ins.....How big is it?
Have also read that going past 3 rows of tubes in a rad can be counter productive as the airflow is restricted.
I have elec fans on a couple of cars. You need to compare the rated cfm (cubic ft/min), current draw, and how much of your radiator core can be covered. Squarish rads are probably best served by a single large fan, where more rectangular rads might do better with 2 smaller diameter units. I have a twin 11" SPAL set up on the 928 (wide rad), 2700cfm. The sealed SPALs seem to have very good life guarantees, and their shrouds have blow-open flaps so that when on the move there is plenty of airflow. Watch out for very high cfm that might come with no warranty as they are intended for racing use - eg 3000cfm , 16" unit. I am not a fan of temp probs stuck into radiator fins, much prefer sensors in the coolant. There is a huge range of sensors available, and now you can buy adaptors that splice into the top rad hose. I have read that puller fans (behind rad) are more efficient than pushers (in front). Also note re DC electric water pump that when a local web based automotive 'magazine' did a test years ago on the DC pump they told DC they were about to publish and were served an injunction to desist, and its never been published.
 
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#6
Thanks for the knowledge. Sounds like Revotec or Spal, sucking rather than blowing, is the way to go. And an inline thermostat in the top hose. A capillary probe jammed between the radiator stub and the hose seems a bit of a bodge and a leak waiting to happen, although I had such a system on a Lotus Elan I once owned and it seemed to work OK.
 

mrtask

Well-Known Member
#8
My Revotec top hose thermostat fan controller thingydingy performed flawlessly for a year, and then suddenly and inexplicably died. No idea what went wrong, but the black magic used to happen somewhere inside a blob of resin that my learned mechanic friend said prohibited repair. On his advice I replaced it with an aluminium tube section with a threaded boss to take a replaceable temp sender. If this sender dies I can unscrew it and pop a new one in. I'm afraid I can't remember either manufacturer name, but I'm sure a quick web search will enlighten. I have a wopping great Kenlowe push fan in front of an uprated rad from Wadhams, which – after having to have the shonky substandard ovalised filler spout replaced – has also performed well thus far.
 
#9
I bought a reconned three-row rad for my 2000TC which has a fitting for a temperature sender/switch. I'm yet to get one though, still have a manual switch at present. Though saying that, there's no fan fitted either at the moment.
 
#12
Having being bought up on stick and oxyacetylene welding I couldn't for the life of me get on with MIG, until I went on an evening Welding course at the local agricultural college. I cannot say I am brilliant as I don't get enough practise for one thing, but it all fell into place with proper tuition.
 
#13
Note that I said 'going past 3 rows....' meaning 4 or more rows can be counter productive. Implies that 3 rows can be OK. Also I have seen significant differences in fin density in cores. In some cores the fins have tiny holes and bent tabs that move air between fins to improve flow, but they have to be fitted to the tanks in a specific way or they dont work properly.
This page makes interesting reading , relevant here.
Cooling the Sunbeam Tiger by Tiger Tom and Chuck King – TigersEast AlpinesEast
While much is specific to the layout of the Alpine/tiger, some is relevant to our cars. Note the mention of the value (at idle) of a baffle between the radiator and the crossmember to prevent recirculation of hot air - will try this out next summer. Such a baffle will also keep road debris and water out of the belt runs. Also note the observation that electric fans with fewer wide paddle blades were more effective than those with many narrow blades.
At least we have a temp gauge that gives real readings instead of the modern practice of severe damping.
In MX5 from mid 90s I interpret the gauge as Cold, OK, Head gasket. In my Subaru Turbo I can see real temps on an OBD-II display - have never seen the car's gauge above 45% of scale, where the real values range from 83C to 96C, and on a Mazda3 have seen 100C on OBD-II, with the gauge at normal.
 
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