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Plastic versus metal
https://ausmini.com/forums/viewtopic.php?f=2&t=21218		 Page 1 of 1
Author:  sparkyboy [ Mon Aug 07, 2006 8:53 pm ]
Post subject:  Plastic versus metal
Hi guys, just a quick one but which do you think is better, a plastic fan or a metal one? I notice the new ones for sale are all plastic. Any reason to bung a plastic one in as part of the build? Or is it just a matter of preference. I imagine the plastic one is lighter and would do less damage to anything getting in it's way (mind you I imagine a plastic one would do a fair bit if damage as well).

Dave
Author:  DOZ [ Mon Aug 07, 2006 9:27 pm ]
Post subject: 
Plastic 16 blade vs
a) 4 blade metal
- plastic is quieter and more efficient (uses less HP for same rpm)
- but plastic blades have been known to break off and embed themselves in radiator
- 4 bladers keep engine cooler (my experience, could be argued though)

b) 16 blade metal - good for chroming, otherwise they are shite, plastic better

If you intend track work, I would try to fit davies craig electric fan. They won't mind high engine rpm (not being connected), hence are unlikely to break and they turn at higher speed at idle and this is where the main issue of inadequate cooling starts.

DOZ
Author:  drmini in aust [ Mon Aug 07, 2006 9:35 pm ]
Post subject: 
DOZ wrote:
Plastic 16 blade vs
a) 4 blade metal
- plastic is quieter and more efficient (uses less HP for same rpm)
- but plastic blades have been known to break off and embed themselves in radiator
- 4 bladers keep engine cooler (my experience, could be argued though)

b) 16 blade metal - good for chroming, otherwise they are shite, plastic better

If you intend track work, I would try to fit davies craig electric fan. They won't mind high engine rpm (not being connected), hence are unlikely to break and they turn at higher speed at idle and this is where the main issue of inadequate cooling starts.

DOZ

I take issue with b), the 16 blade is way quieter than the POS plastic ones. Try if you don't believe me. Oh and they don't fling blades off like plastic do. :x
:wink:
Author:  sports850 [ Mon Aug 07, 2006 9:38 pm ]
Post subject: 
I've always been led to believe the 4 blade metal fan was the best (well , half the 4 blade is supposed to be optimal) , followed by the 16 blade metal fan and then if you were desperate the plastic one . It's all to do with distortion , apparently the plastic ones distort and become less efficient at high revs while the metal ones don't , or at least distort less . Still , I think a thermo fan would beat all of them for a serious motor anyway .
Author:  harvey69 [ Mon Aug 07, 2006 9:48 pm ]
Post subject: 
from what i remember reading the 4 blade metal one is better for racing use as it allows more air to pass throuugh at higher revs.... and vise versa for the plastic.....

i hve a plastic one ..... 50 buks from ebay and its fine for racing around town ,,,,,,
Author:  Hanra [ Mon Aug 07, 2006 9:53 pm ]
Post subject: 
Ive got a 6 blade metal. I found it a little more noisy then the plastic 16 blade job. But now the exhaust and stereo is that loud i dont hear it. I reckon cooling was improved as well!!!
Author:  Checkered Green [ Mon Aug 07, 2006 10:40 pm ]
Post subject: 
when i saw "plastic versus metal" i assumed this would be about new versus old minis. It just reminded me of a good sticker i saw a while ago:

"Classic Brit not German crap"

Just thought id share that!
Author:  MINImal effort [ Mon Aug 07, 2006 10:44 pm ]
Post subject: 
I had a 6 blade fan that threw a blade back in the eighties....

Had just bought it off my brother-in-law and was being driven up from Melbourne by a mate of his after I had ran out of time to get it roadworthy before I had to come back to Canberra a week or so earlier.

Apparently just outside Wagga threw the blade which punched a nice hole in the bonnet before dropping out... have the photos somewhere .....

So I've only really driven it with a plastic fan.... (just never chased up a metal one)
Author:  DOZ [ Mon Aug 07, 2006 10:58 pm ]
Post subject: 
I've had 4 blade, 16 blade (metal & plastic) and found the plastic ones are reasonably ok if you trim them (similar to back cutting a turbo) to stop high rpm flex. I have experienced several failures with plastic ones, which lose 'limbs' at high rpm, hence the warning.

My engine currently has a trimmed plastic fan together with a davies craig thermo. I am going to try to remove the engine fan and improve ducting as I think the thermo will be enough on it's own for my usage.

I should add that i've never fitted a 6 blade but would expect they are as good (at cooling) as a 4 blader with slightly less noise.

The 4 blade metal would be my choice over the plastic if I had the room (i don't) and didn't have a thermo fitted, I have never had a problem with one of these but they are noisy.

DOZ
Author:  Flying Brick [ Tue Aug 08, 2006 8:03 am ]
Post subject: 
I just replaced my plastic fan with a 16 blade metal, the plastic one had 2 1/2 blades missing and over about 2500rpm the vibration was really bad. The metal fan on now is great , no noise and cools just fine. Although this morning I probably could have run with no fan as was pretty cold. Heater takes about 20 min to blow warm air.
Steve.
Author:  El Venessian [ Tue Aug 08, 2006 8:13 am ]
Post subject: 
DOZ wrote:
I've had 4 blade, 16 blade (metal & plastic) and found the plastic ones are reasonably ok if you trim them


Hi DOZ, how much of the blade would you recommend to trim off?
Author:  Lillee [ Tue Aug 08, 2006 9:07 am ]
Post subject: 
I have had both in the same engine and I can tell you that the metal one is quieter than the 16 blade. I'm undecided which is more efficient or draws less hp... both about the same in a cooling system that is tip top shape, city or highway...
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