Hi

Just doing a few improvments to the cooling system and am wandering which is the most efficient radiator fan to use.

The multiblade plastic fan or the earlier type metal fan , or anything else.

Thanks in advance

Not exactly sure what you mean by 'efficient' however the 6 blade 'Export' Fans (if you can find them) push the most air but are noisy. The plastic 11 bladers are good, push a reasonable amout of air, about the quietest of the stock fans and don't suck too much HP from the engine. A two bladers sucks the least HP, is noisy but doesn't push much air either.

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I find the 16 blade metal fans work fine and are quieter than the plastic ones. They don't bend or throw their blades off either.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I used to think all plastic fans were the same but have found they vary in blade chord length. Here is a selection that I seem to have accumulated:



Blades have different chords but length is the same until they rub on the rad cowl:



And a close-up showing how much they vary. Quite a big range! I have no idea of what the difference in airflow or noise there is between them and I never learnt that part of aerodynamic theory when at uni (would have forgotten it now anyway).



Maybe someone can shed light on the sources of different fans and how they perform?
M

The wider chords were probably introduced simply because they would flex a lot less. As the engines got bigger and more powerful, the parasitic drag was less of a concern and the wider ones would move more air.
The reasoning sounds pretty good in my head anyway

The white plastic ones were designed to become brittle & disintegrate into the radiator at speed

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Too many cars, and too little time.

Ive been happy with my 6 blade metal fan. Prob is a bit noisy but I cant hear it over the exhaust.

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http://www.youtube.com/user/Hanras

i use a 4 blade.

2 2 blades on top of each other, pushes a monster amount of air, very cool, rather loud, but does the job, like hanra said, cant hear it over the zoorst anyways...

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Here am I sitting in my tin can far above the Moon
Planet Earth is blue and there's nothing I can do...



“A turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.” - Jeremy Clarkson