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Serpentine Clutch Fan: 7 or even 9 blades possible?

N

ntsqd

1/2 ton status
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Looking at my '91 Sub for reference I see that it is a 5 blade. However I'm doing a 5.7l TPI swap into an SOB (SomeOtherBrand) and since the Sub radiator that I had earmarked for this project does not fit I'm having to use a smaller radiator. Ironically the one from the Z-28 donor fits rather well. Too bad it's got a puny core and this rig will be towing in the deserts of the South West.

So I'm looking for more fan than the 5 blade on my Sub to use with the donor's core size (in a thicker core). Checking the various online parts parts all that I'm finding are 5 bladed fans. Searching here didn't turn up much on the topic either, but my search-foo is not as strong as I'd like it to be. I've got this very nice 7 blade clutch fan, but it's for a std rotation which does me no good (free to a 93003 local).

So, does anyone know of a reverse rotation fan clutch fan with more than 5 blades?

(Just for the record, I have Zero interest in going to electric fan(s). Just is not going to happen on this build, mentioning it is a waste of your time.)
 
ntsqd said:
Looking at my '91 Sub for reference I see that it is a 5 blade. However I'm doing a 5.7l TPI swap into an SOB (SomeOtherBrand) and since the Sub radiator that I had earmarked for this project does not fit I'm having to use a smaller radiator. Ironically the one from the Z-28 donor fits rather well. Too bad it's got a puny core and this rig will be towing in the deserts of the South West.

So I'm looking for more fan than the 5 blade on my Sub to use with the donor's core size (in a thicker core). Checking the various online parts parts all that I'm finding are 5 bladed fans. Searching here didn't turn up much on the topic either, but my search-foo is not as strong as I'd like it to be. I've got this very nice 7 blade clutch fan, but it's for a std rotation which does me no good (free to a 93003 local).

So, does anyone know of a reverse rotation fan clutch fan with more than 5 blades?

(Just for the record, I have Zero interest in going to electric fan(s). Just is not going to happen on this build, mentioning it is a waste of your time.)
Click to expand...

I have seen them in 6 blade, gotta look to see if i still have that one in my shed.
 
Why would you need anything other than a 5 blade fan. As long as your cooling system is clean and working properly, the 5 blades are more than enough to do the job.
Run a larger radiator, and a heavy duty fan clutch, you'll be suprised at just how much better the heavy duty clutch will perform.
 
Only fans i know that have more than 5 blades are the ones used on the vortec motors. They are the ones that screw on to the water pump.

They are also plastic.
 
You could recore that radiator.
Sometimes they can use the same tanks but put more rows in.

ntsqd said:
Looking at my '91 Sub for reference I see that it is a 5 blade. However I'm doing a 5.7l TPI swap into an SOB (SomeOtherBrand) and since the Sub radiator that I had earmarked for this project does not fit I'm having to use a smaller radiator. Ironically the one from the Z-28 donor fits rather well. Too bad it's got a puny core and this rig will be towing in the deserts of the South West.

So I'm looking for more fan than the 5 blade on my Sub to use with the donor's core size (in a thicker core). Checking the various online parts parts all that I'm finding are 5 bladed fans. Searching here didn't turn up much on the topic either, but my search-foo is not as strong as I'd like it to be. I've got this very nice 7 blade clutch fan, but it's for a std rotation which does me no good (free to a 93003 local).

So, does anyone know of a reverse rotation fan clutch fan with more than 5 blades?

(Just for the record, I have Zero interest in going to electric fan(s). Just is not going to happen on this build, mentioning it is a waste of your time.)
Click to expand...
 
nvrenuf said:
6 blade fan = http://www.polyperformance.com/shop/Derale-Fan-Clutch-Fan-p-17273.html

Serp clutch = http://www.polyperformance.com/shop/Thermal-Fan-Clutch-Reverse-Rotation-p-17282.html
Click to expand...

nvrenuf, Muchos Gracias! I did not know that there were any aftermarket fans for clutch fans.

4xcrazy said:
Why would you need anything other than a 5 blade fan. As long as your cooling system is clean and working properly, the 5 blades are more than enough to do the job.
Run a larger radiator, and a heavy duty fan clutch, you'll be suprised at just how much better the heavy duty clutch will perform.
Click to expand...
I'm guessing that you missed the part about towing in the desert and that a larger radiator doesn't fit in this vehicle? Making a larger one fit just isn't an option unless I want to fabricate a completely new core support, which I am not about to do until it is proven the only option left. If it comes to that, then I'll build it to fit my old '79 3/4t Sub's HD "Desert Cooler" radiator sitting in garage rafters. It was prepped and made ready to go for this project.
Engine swaps nearly always run hot, I want to cover all of the easy steps before I even turn the key. A HD fan clutch is a given.
BTW, your avatar needs to be a full length movie!

imiceman44 said:
You could recore that radiator.
Sometimes they can use the same tanks but put more rows in.
Click to expand...
Plastic tanks and aluminum core in the donor radiator. No thanks. There may be a slight advantage in cooling with a aluminum core, but too many friends have had too much trouble with them. One overly-anal engineer friend (Pot, meet Kettle?) never could solve his problems with multiple Ron Davis radiators and that was with the help of a friend who was fairly high up in RD.

FWIW I will be building a fan shroud using the stretchy fabric & fiberglass method once the radiator is set and the fan & fan clutch are in place.
In case anyone cares, the build thread, which mostly me mentally masturbating:
http://forum.ih8mud.com/60-series-wagons/336261-my-84-60-build-wallace.html
 
I didn't mean bigger, as in overall size, i meant as mentioned, more rows of cooling. I bumped mine up to a 4 row radiator for that added cooling capacity, it helps a ton with that added row, and of course i'm running one of the heavy duty fan clutches.

It runs at t-stat temp all the time, maybe a hair higher when towing and whatnot.
 
Why not do it right and buy an aluminum radiator that fits and has the cooling capacity you need. Seems to me if the 2 core from a car will fit then a 3 or 4 core with the same dimensions would also fit. It is not like the tanks are any bigger.

With the number of big motors out there in Cars now adays they must not be using the stock radiator to keep them cool.

Dik
 
The fan on my TBI 350 from a one ton has a 6 blade fan, but it's not serp. Seems the 1 ton stuff would still have better fans, have you checked if stock replacement fans for a 350 or 454 in 89 or newer 1 tons are more than 5 blade?

Rene
 
One guy at a local radiator shop cautioned about going too thick with the radiator core. His argument against a 4 core is that they can cut the airflow down to the point where a 3 core will actually provide better cooling. I can see his point, but I don't know that he is correct in my application. He wasn't making a universal statement, just cautioning that it is something that I could run into.

I had looked at the higher GVW applications for the fan, but only within this body style. I'll have a look at the IFS trucks and see what they might have.

EDIT: Looks like the later 3500's have a larger diameter fan that is still 5 blades. At least that is what Rockauto thinks anyway. Based on fitting a small, wrong direction fan & clutch assembly on the engine and measuring with the hood closed I think that I can clear a 20" OD fan, but just barely.
 
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Historically, Suburbans with big blocks and rear a/c got the biggest fans. The '97ish 7.4L did have a 9 blade rev rotation blade, but I am not sure on the diameter (typically the dealer listing will have the diameters). If it ends up too large in dia, check a small block. I know one of these 9 blades fits in a small block shroud. BTW, both are plastic, but will bolt to your fan clutch.
 
Thanks Mosesburb,
I'll have to do some digging as I've not yet found an OD listing for those, but they look really promising!
 
bronc3buster842001 said:
Only fans i know that have more than 5 blades are the ones used on the vortec motors. They are the ones that screw on to the water pump.

They are also plastic.
Click to expand...


gm makes or at least they made a metal 7 blade clutch fan for 2nd gens, every 400sbc truck I've ever seen had them..option charts say they came w/hd cooling package & on trucks w/auto/ac/towing package on them as a package. i have 7-8 of them, i snag every1 i run across, maybe a southern thing :dunno:

..heres a couple pics of 1's i had handy. i'd like to know the difference between these clutches..1 has the wound spring thingy up front, the other doesn't, its smooth.

DSC00200.jpg


DSC00201.jpg


DSC00202.jpg
 
I have a 7 bladed clutch fan now. Came from my '79, which originally had a 400 and was sold new in KA's central valley (Fresno to be exact). The problem with it is two-fold; it is for a std. rotation water pump as yours look to be (hard to say for sure in the pics), and the reverse rotation water pump pulley/fan flanges have a different bolt spacing so that the wrong rotation direction clutch (apparently) can't be bolted to it.

The spring thingy is a bi-metal spring like was used in some carb chokes. That makes that clutch temperature sensitive rather than just rpm (or whatever) sensitive. I'm not sure exactly how it works inside, but for my own use I wouldn't bother with a clutch that doesn't have it.

Just wanted to say that y'all have been a great help. Reminds me of why I highly valued this forum when I had my Sub's.
 
if the new plastic 9 blade will bolt to our clutches, as mentioned....wouldn't our fan bolt to that reverse flow engine clutch...then flipping the blade 180*..??reverse the air flow..??i never had work a reverse flow..to many old sbc's sittin around, guess i need to read up more on them..well my 96 tahoe is reverse flow, but i have never had to ''work'' on it..fluids,belts,brakes..86k miles..runs good..sounds good!
 
blazin_blazer said:
if the new plastic 9 blade will bolt to our clutches, as mentioned....wouldn't our fan bolt to that reverse flow engine clutch...then flipping the blade 180*..??reverse the air flow..??i never had work a reverse flow..to many old sbc's sittin around, guess i need to read up more on them..well my 96 tahoe is reverse flow, but i have never had to ''work'' on it..fluids,belts,brakes..86k miles..runs good..sounds good!
Click to expand...

no, blades still at the wrong pitch direction.
 
Generally speaking, while there is a slight decrease in air flow with a thicker radiator, the added surface area and amount of coolant more than makes up for it.

However, don't forget, there is more things to cool an engine with than just coolant.

Running an oil cooler will suck a large amount of heat out of an engine.
And just because you totally vetoed electric fans, I'm going to throw one in.

But mounted to the oil cooler instead of the radiator.
Mounting the oil cooler out of the direct air flow from the radiator with its own small dedicated fan, is a win win situation.

It cools the oil, and does not add to the heat load that the main fan has to get rid of.

If you have an automatic tranny, you can give it its own cooler too.

There are pros and cons to making that the only cooler for the tranny.
Most people add it to the existing loop in the main radiator. But, if its only going to be used in hot weather, you can usually get away with bypassing the main radiator.

In cold weather, from what I understand, having the radiator in the circuit helps the transmission to warm up faster.
Warm transmission fluid flows better, and helps keep any varnish or other impurities suspended in the oil.
 
I have a plan for the engine oil cooling and trans fluid cooling. There will be a liquid to liquid heat exchanger in the radiator for the trans fluid. It will be the primary cooling source, but there will be an 11" x 11" stacked plate type aux. cooler on a Mocal thermostat in that system. Engine oil cooling will have the same size cooler and use the OE adapter and most of the plumbing from my '79's 400 c.i., unless the exhaust forces me to go remote with the oil filter. In which case I'll need a second Mocal T-stat for the engine oil cooler. There will also be what most people use for a small aux trans cooler in the PS return.
Space on an FJ60 is such that they will all have to live on the core support. At this point I do not know how much they will intrude on the radiator & A/C condensor, but at least some overlap is inevitable.

This is why I want as much fan as I can get and make fit.

Re: 4 core vs. 3 core vs. 2 core air flow restriction. Assume that the 2 core's restriction is "10" of what ever units. If the 3 core's third core is built exactly the same way as the two cores in the 2 core radiator, then the flow restriction is now "15".
If the 4 core repeats the same process then it's flow restriction is now "20". That's pretty simplified (turbulent flow could actually make things worse than this), but this is the same thing as resistors wired in series, they're additive. I'd have to get out my old Thermo book to be sure, but as I recall thermal transfer mass flow rate, thermal conductance, and surface area are the prime factors in the rate of thermal transfer. Slow down the mass flow rate and the thermal conductance will be reduced. Increase the surface area and the transfer rate will increase. So the balance is finding the core with the largest ratio of surface area to flow restriction possible.
 
I don't know why they would say the more core radiator would cause air restriction, if it does, it's very minimal, it's not like the cores are staggered like the tubes on an AC condensor are, you look through a radiator core, you can see straight through them, it's just more surface area for the air to pass over is all, and thus removing more heat from the coolant.
 
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