47-55.1 Electric fan setup?

[Matt_50]

With a new water pump in and the radiator installed, I'd like to maybe go with an electric fan set up if I can get it to fit. Nevermind the top radiator hose, still need a different thermostat housing...
Currently no A/C but I plan to get one in the future.

I know absolutely nothing about fans. What size do I need? Fan shroud? One fan or dual? CFMs? Which brands are good, which are bad?

I tried to get some good pictures. Looks like the core is 20 tall and a little over 19 wide. Looks like a little over 2.5 inches between radiator and water pump. There is about 14 inches or core above the water pump.

Any advice you guys have would be awesome.

[MiraclePieCo]

It has been my experience that advertised CFM ratings are mostly baloney - except for Spal. Spal fans pull so hard that they'll almost suck your truck down the road like a propeller on an airplane! They're worth the extra money.

You have plenty of room. Get the widest fan that will fit. Single will work fine. Mount it as high on the radiator as possible. They say S-curve blades are quieter. Thermostatic switches are convenient; you never have to worry about turning them on. They come with relay kits.

I'm glad to see you using the stock style radiator; they have lots of coolant capacity. I have a hard time getting my motor above 140 degrees.

[Matt_50]

Should i make a fan shroud?

[my56chevytruck]

Originally Posted by Matt_50

Should i make a fan shroud?

you don't need a fan shroud, although they help, and you don't have to mount your electric fan dead center of the radiator either. Yes, a SPAL fan is by far one of the best and I've used many styles, SPAL's do a great job.

[Matt_50]

And if spal is reliable on their cfm ratings...

Do I need the recommended 2500 cfm? I don't want to go broke but I want a good reliable fan that doesn't sound like I'm about to fly.

[joedoh]

I will try to use a clutch fan until it just doesnt fit. you dont look to have a lot of room there.

a clutch fan is deeper than a flex fan, but it will turn off when not needed, a flex fan is always cutting air.

if electric is all that will fit, most have enough shroud on them and dont need one that covers the whole rad. those will actually restrict airflow when the fan is off.

using a fan controller is better than a simple thermo switch, but a good thermo switch and relay is pretty reliable too. They sell an import upper neck fitting that has a spot for a switch if your intake doesnt have a spot.

I use curved blade generic fans when I cant use a clutch fan.

[popstand]

Modern cars use electric fans not clutch fans. Actually, the clutch fans were not trouble free. I replaced a few of those things in my 60’s gm cars. The clutch fan in my old van is noisy as hell first thing in the morning.

I installed a Derale 16516 electric fan in my ’53, this is 16 inch, 2175 cfm, I installed it ‘pulling’ with no shroud. The 16 inch pretty much covers the radiator and looks nice.

In my truck with a 350 V8, a water pump fan, even if it would fit, would be pretty low to the radiator. Looks like yours is the same. I don’t have a/c.

Electric fans can run after you shut off your motor to continue cooling.

You might want to do a boneyard search for an electric fan package. Maybe some of the guys on the forum have done this. Some of the oem fans are two-speed.

[joedoh]

Originally Posted by popstand

Modern cars use electric fans not clutch fans.

sure do. some because the engine is transverse (the crank is parallel to the front wheels and a mechanical fan would be blowing out the side) some because of packaging where a large cooling fan would not fit. there are still clutch fans in service, usually in the most extreme duty cases.

also, let it be said that all oem electric fan setups, every one of them, have millions of dollars of R&D by hundreds of engineers involved with all aspects of the fan turning on and turn off, software coding, cooling efficiency, reliability, servicing, testing in extreme climates and a lot of other things that the home builder guy picking a fan from summit and a thermo switch from amazon is not concerned with.

but I agree he doesnt have room for a clutch fan.

[Matt_50]

I'm assuming an electric fan is preferred over a flex fan because the flex fan is always going right?

Derale is another brand I've come across that sounded like good quality. 2175cfm is enough Popstand? For a regular putter around occasional highway 350?

Does the cfm change if I am using the trans cooler in the radiator?

I'm still confused on a shroud. Would I want to cover the the whole Radiator? From my searches I found a few guys did flaps. Or do I start with no shroud and go from there?

Joedoh you mentioned using generic fans, I have no idea which ones are junk or not.

[NorCalGal]

This is what I used a delta pag programmable

[MiraclePieCo]

Originally Posted by Matt_50

I'm assuming an electric fan is preferred over a flex fan because the flex fan is always going right?

Derale is another brand I've come across that sounded like good quality. 2175cfm is enough Popstand? For a regular putter around occasional highway 350?

Does the cfm change if I am using the trans cooler in the radiator?

I'm still confused on a shroud. Would I want to cover the the whole Radiator? From my searches I found a few guys did flaps. Or do I start with no shroud and go from there?

Joedoh you mentioned using generic fans, I have no idea which ones are junk or not.

When researching electric fan specs, look at amperage rather than CFM. Most CFM stats are made up; amps is the real indicator of a fan's pulling power.

Electric fans generally have a built-in shroud. They are adequate to align air flow without blocking ambient flow through the radiator like a full coverage shroud.

Derale is a decent economy brand.

As far as fan location near the bottom of radiator goes, it hasn't seem to hurt my truck's cooling capability at all. In fact, if you look at the original factory fan setup from GM (below), they were quite low on the radiator:

[MiraclePieCo]

My water pump mounted mechanical flex fan will never have a thermostat, wiring, clutch or motor failure. I've had all those things fail on modern fans. The only thing that could fail on a mechanical fan is the belt, and that drives the water pump too so you'll being stopping soon anyway.

Just another example of old-fashioned manual stuff being more reliable than complex modern technology, as I've been debating with Dan in Pasadena.

[NorCalGal]

Originally Posted by MiraclePieCo

My water pump mounted mechanical flex fan will never have a thermostat, wiring, clutch or motor failure. I've had all those things fail on modern fans. The only thing that could fail on a mechanical fan is the belt, and that drives the water pump too so you'll being stopping soon anyway.

Just another example of old-fashioned manual stuff being more reliable than complex modern technology, as I've been debating with Dan in Pasadena.

I have twice in my life seen where a flex fan blade has come off while running and shot out through the metal hood. I cringe every time I see people stand in line with the fan while the motors running with the hood up. Odds are it won’t happen but I know it is possible

[65blackfleetside]

2nd vote for spaL top of the line fan. Don't waste your money with chinese junk fans.
If you don't have a shroud yet you can make one for less than $30.00 .
Do you have a GFS commercial food supply store near you? They sell the large commercial grade aluminum baking /cookie sheets. One off the shelf fit my new aluminum radiator perfectly and I was limited on space like you. Just cut your hole for fan. mount fan to back of baking sheet with small lock nuts and bolts. The original flange of sheet mounts perfectly to back of radiator. My truck is at the painter or I would post picture. When I show people the shroud they have no idea that it was a baking sheet.

[NorCalGal]

Oh and 2.7 inches thick

[Matt_50]

I have been searching and searching..

I'm trying to not only find a good all in one kit, bit also looking to see what others have done.

Apparently solidaxle found a mopar fan he put in I think three trucks.

[Matt_50]

Look at the amps? What range should I look for?

Are flex fans bad about falling apart? Would a flex fan interfere with wanting to use the radiator's trans cooler? I mean where the connections are?

[Matt_50]

And being low on radiator like you said... from searches, a lot of people say a fan should cover 70% of the radiator.

Is this true?

[MiraclePieCo]

Originally Posted by Matt_50

And being low on radiator like you said... from searches, a lot of people say a fan should cover 70% of the radiator.

Is this true?

That 70% figure actually comes from the Flex-A-Lite fan page. https://www.flex-a-lite.com/blog/whi...lt-driven-fan/
It's a good policy, but I'm here to say that I'm actually running a low-mount mechanical fan with a warmed-over SBC and my temp runs a consistent 140 degrees. The outside temperature here has been around 90 this week. Looks like I may actually have to install a hotter thermostat just to get my motor up to temp!

Regarding the tired old "flex fan decapitation" stories: My flex fan is rated for vastly higher RPMs than my motor is capable of; no doubt those fans that came apart were either cheap, damaged, abused, or all three. We know they didn't have a shroud!

I've used both mechanical and electrical fans. In every case the mechanical has cooled better. Plus I take comfort knowing I'll never be stuck on the roadside due to blowing a 15-cent fuse. My fan will never stop working as long as my engine is still running.

.

[popstand]

MiraclePieCo is right, you don't need a shroud. Our trucks have a big radiator and a big grille - lots of air. That shroud is going to restrict air-flow thru the radiator and you're going to have cooling problems. These electric cooling fans are not full time, they turn on and off as needed. Yours will be on full time.

[e015475]

To each his own, I guess.

Around here, most custom cars/trucks have problems keeping the engine cool in stop and go traffic with the ambient ant 115F and the additional heat load of an AC condenser.

It really doesn't matter how big the frontal area of the truck is when it is stuck in traffic, because there's no ram air effect stagnating air in front of the radiator and creating pressure differential across the radiator- all that matters is the amount of airflow the fan can pull across the radiator. And it is just physics that a fan in a shroud (correctly designed) is more efficient than a fan just hanging in the airstream.

I can't recall a single production car I've seen in the last 20 years that didn't have a shroud to direct air through the radiator. Both electrical and mechanical fans seem to work, and anecdotally, it seems like there's a lot less overheating problems now than there was when I was a kid 50 years ago and these truck were commonplace. Engineering marches on.

It is your prerogative to run unshrouded like the fan in the pic of the previous post, but I'll stick with a shroud and a big fan where I can idle in stop and go traffic without overheating when it is 115F outside and 140F on the black asphalt. I'm resigned to sticking around this god-forsaken hell-hole in the summer, and I don't want the aggravation of overheating while enjoying my truck.

Best of luck with yours.

I've got to stop answering posts like these with a drink in my hand!

[Clarance J]

I had over heating problems with my truck with the new electric fan I put on. I didn't like it at all. I couldn't get all the switches, relays, thermostat and on/off plus the shroud I made (which did not work like I planed) wiring etc to work together. I decided to go back to the old flex fan I had before with new shroud design. This one worked really well. No more overheating problems. If you are interested in how I made it can be found in my build thread #333 thru 348. I went back to mechanical because there are way less things to worry about. Lotta work but well worth it to me.

Earl

[popstand]

I don't really care whether production cars today have shrouds. My truck will run just fine with no fan at all at normal road speeds. It does need the fan in traffic, stop and go stuff.

I'm guess I'm at a disadvantage here. Besides being a hot rodder for 65 years, I spent over 40 years involved in automotive powertrain development, mostly with GM. Included in that at one time was prepping prototype cars for climate wind tunnel testing at Harrison Division. Harrison made GM radiators.

[Matt_50]

I think I will try without a shroud first. Thankfully I don't live in Dallas anymore and I wont be sitting for forever at times.

But if I do need a shroud I like the cookie sheet idea.


If the fan tapers towards the end and looking t my first measurements.... Will a 16 inch fit?

[Volfandt]

I'm running a SPAL 16" electric fan on a stock 49 GMC radiator with a 350 and unless I'm idling for an extended time (long red light, drive through window) or I'm running over 60mph the fan never comes on. The sender is 200 on / 185 off. I also added a manual override toggle switch in case of sender failure.
Space and a low mounted 350 dictated the electric fan. So far after 1 yr no heat related problems...

In the pic above of the Stovebolt engine I believe thats probably a 55 or later 235 or 261 with the low waterpump, thats why is so low and not centered on the rad.

I'm attaching a pic of a stock 216 in a 49 3100 with the high mounted waterpump which centers the fan on the rad. I run a 160 thermostat in that 216 and never get above 185, even on 90 degree days. It's generally centered at 180...