Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.
udoittwo
Posted 2019-07-05 9:55 PM (#584484)
Subject: Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.



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I have a 1960 2 ton plus vehicle moved by a stock 1960 318/ 2 speed automatic. Although my 4 blade fan[no shroud] has done the job even while towing my boat in 90+ degree heat with high humidity and moving no where on the turnpike.
The temp would go way up but it never topped out or overheated. I thought that I would be kinder to take a little less strain off her as I traveled north again towing my boat for 6 hr drive this summer. So here is what I did and what THOUGHT would be changing from a 4 blade metal fan to a 6 blade fan...

I got this 6 blade fan from Summit. I Expected it to be a little lighter but it is a LOT lighter. This fan is solid plastic. I guess/expected it might be metal? It is AT least half the weight.

My original fan was less than 1' from the radiator. This new fan is thinner and is almost 1 1/2" away from the rad.[I expected it to be about the same as stock].

To get at the bolts and remove the 4 blade fan took around[+/-] 1/2 hr. I expected a 6 blade fan to be even harder to get to the bolts - 10 or less minutes and I was done[?].
Pleasant surprise.

I had read and expected it to be a lot noisier but it is actually quieter.

I was HOPING it would run cooler but so far, it seems to be about the same. That MAY show up somewhere on a stopped in traffic hot day? Jury is still out on that but that was why I made this change[I'll carry the old fan along].

Honestly, I could care less about performance beyond what i expect a 1960 318 should do and NEVER even thought or expected any change but when I left my house, I swear it was running a lot better.

My question is - I know 1 pound to someone that races might be another MPH down the track. Is it in any way possible that this little amount of change might be noticeable to someone like myself that was not looking for it or is it just a coincidence that all conditions made it seem to run better?
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Powerflite
Posted 2019-07-05 10:34 PM (#584485 - in reply to #584484)
Subject: Re: Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.



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The answer is yes, because the plastic blade flexs more at high speeds and reduces the drag on the motor. The reduced drag will pull less air through the radiator, but at high speeds, it isn't needed as much anyway. The fan really needs to work at low speeds so it's a good trade-off.
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57chizler
Posted 2019-07-06 1:07 PM (#584499 - in reply to #584484)
Subject: RE: Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.



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Other than the diameter and number of blades, the thing that moves air is the pitch of the blades. More pitch, more air and more noise. I'm of the opinion that flex-fans don't improve performance as much as advertised. I've got a pile of them that I've removed over the years.
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1960fury
Posted 2019-07-07 8:08 AM (#584513 - in reply to #584499)
Subject: RE: Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.



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57chizler - 2019-07-06 1:07 PM

I'm of the opinion that flex-fans don't improve performance as much as advertised.



That conforms with the comprehensive Dyno testing done by Mopar Performance. Flex fans gave little improvements, probably only because they weight less than the oe steel blades. that is why the known clutch system got the Mopar P-parts number.
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57chizler
Posted 2019-07-07 1:10 PM (#584520 - in reply to #584513)
Subject: RE: Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.



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The most aggressive fan I ever used was a 20" 7-blade clutch fan from a cop car, the blades were about 4" wide and it sounded like a hurricane but it moved some air.

Later on I tried to use the same fan direct drive (no room for a clutch) and it slipped the belt at anything over 2500 rpm.
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jboymechanic
Posted 2019-07-07 10:30 PM (#584538 - in reply to #584484)
Subject: Re: Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.



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Find and buy or make a shroud and you'll get the most out of your fan and your radiator. Distance between fan and radiator is important (even more important if you don't have a shroud), keep it at about 1 inch distance. Also, what temp thermostat are you running? You could go with a cooler one, like 165F.
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mikes2nd
Posted 2019-07-08 2:52 AM (#584547 - in reply to #584484)
Subject: Re: Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.


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Aluminum pulleys, less resistance power steering pump, fan clutch or even electric fan, electric water pump all give horses...

You will notice the gains
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1960fury
Posted 2019-07-08 8:40 AM (#584554 - in reply to #584538)
Subject: Re: Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.



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jboymechanic - 2019-07-07 10:30 PM

Find and buy or make a shroud and you'll get the most out of your fan and your radiator. Distance between fan and radiator is important (even more important if you don't have a shroud), keep it at about 1 inch distance. Also, what temp thermostat are you running? You could go with a cooler one, like 165F.


Yes, the distance is very important, but 1 inch is way too much. The distance is given in the FSM, I don't think it is 1 inch, IIRC under 1/2".

Okay, looked it up, it is 3/4" blade to radiator. I was confusing blade with fan clutch. At the OE clutch it is around or less than 1/2".

Edited by 1960fury 2019-07-08 3:21 PM
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1960fury
Posted 2019-07-08 8:48 AM (#584555 - in reply to #584547)
Subject: Re: Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.



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mikes2nd - 2019-07-08 2:52 AM

Aluminum pulleys, less resistance power steering pump, fan clutch or even electric fan, electric water pump all give horses...

You will notice the gains


You bet. Rotating mass eats HP and gasoline. I did virtually everything to reduce it. Lightweight brakes, lightweight wheels, underdrive aluminium Pulleys, windage tray, smallest possible Alternator (these spin at astronomical rpm's) featherlight aluminum (Mercedes) fan with clutch, removal of the heavy E-brake drum and the use of titanium/aluminum fasteners. I really went all out with that. The result is (with some other mods) 4.9 seconds from 0-60 with an open 2.93 axle and a 330+K miles never rebuild 383.

Edited by 1960fury 2019-07-08 8:49 AM
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56D500boy
Posted 2019-07-08 11:23 AM (#584558 - in reply to #584555)
Subject: Re: Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.



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1960fury - 2019-07-08 5:48 AM
The result is (with some other mods) 4.9 seconds from 0-60 with an open 2.93 axle and a 330+K miles never rebuild 383.


I would really like to be there with a stop watch to see 4.9 seconds 0 to 60 mph, especially with a 2.93 highway ratio *and* an open diff.

One 0-60 estimator suggests that to hit 0-60 in 4.9 seconds with an automatic and 3800 lbs you would need 395 hp at the flywheel. You must have some 383 there or a 3600 car (and 372 hp)

https://www.carspecs.us/calculator/0-60



Edited by 56D500boy 2019-07-08 1:52 PM
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jboymechanic
Posted 2019-07-08 12:51 PM (#584559 - in reply to #584554)
Subject: Re: Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.



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1 inch is the number I have from my Flex-A-Lite fan install instructions. I used this fan on my 1960 Plymouth only because it was readily available, it seems to do the job on my 1960 Plymouth 2 door sedan with 318 poly. I have a 4 barrel carb and a 4 speed with overdrive, so not a direct comparison to the original poster, but at least similar. I think the key is to keep the fan as close to the radiator as possible to ensure you draw air through the radiator instead of from the area behind the radiator and in front of the fan. You also don't want to get too close that the fan is in danger of hitting the radiator. The distance of 1.5 inches is getting a little far away and may result in less air drawn through the radiator.

I do not have a shroud either, but adding one would make a considerable difference. My radiator is stock and I have never had any overheating (or high temperature) issues. I did flush the engine block when replacing the freeze plugs, I was amazed at the amount of "rust mud" that came out. Perhaps a good cleaning of the cooling system would be beneficial?

Edited by jboymechanic 2019-07-08 12:52 PM
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1960fury
Posted 2019-07-08 3:00 PM (#584565 - in reply to #584558)
Subject: Re: Changed form 4 to 6 blade radiator fan - What I THOUGHT and reality.



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56D500boy - 2019-07-08 11:23 AM

1960fury - 2019-07-08 5:48 AM
The result is (with some other mods) 4.9 seconds from 0-60 with an open 2.93 axle and a 330+K miles never rebuild 383.


I would really like to be there with a stop watch to see 4.9 seconds 0 to 60 mph, especially with a 2.93 highway ratio *and* an open diff.

One 0-60 estimator suggests that to hit 0-60 in 4.9 seconds with an automatic and 3800 lbs you would need 395 hp at the flywheel. You must have some 383 there or a 3600 car (and 372 hp)

https://www.carspecs.us/calculator/0-60

:)


For a Mopar 383 380HP is within VERY easy reach. I said it before and say it again, the low deck big block is the prime Mopar engine with what is considered the perfect bore/stroke ratio and a favorable rod angle. You can get almost any natural aspirated engine to deliver 100hp/liter and that is a conservative statement. 380HP is actually only a ridiculous 60HP per liter. Only the above mentioned mods (and there are others!) should give you the equivalent of 100HP over stock and these had about 280-290 net HP from the factory.

Anyway, note how I have to feather the throttle to avoid tire spin from the start and note this is from curb idle, not a loaded up T/C. The very high mileage T-Flite slips from 2nd to 3rd at WOT so I have back off before it shifts. This is with a home build (completely new design, unlike any other) intake manifold that delivers unbelievable torque:

https://www.youtube.com/watch?v=dvPRrCk01vE

https://www.youtube.com/watch?v=Ga4i09eAhmg


Edited by 1960fury 2019-07-08 3:16 PM
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