ELectric Fans on a Cummins ?

OP here, I've been on this forum for a decade so please call me Dave.

I don't think you're all wet, you are a tad condescending but I have very thick skin.

First, I do not presume to know anything. I work for Phd engineers and the one thing I have learned from them is just how little I can know with certainty.

I have not presented any facts or data that I did not get from some other attributed source. You make a pretty good point- if Flexalite says it draws 60 amps and we know that's 1 hp then why don't the fans have .5 hp motors on them.

So I'll go back to a forum that is more electric fan friendly and ask that question.

I've been following the electric fan debate for a long time. In that time the manufacturers have been putting them on larger and larger vehicles.


Your arguments seem compelling but it's not like FLexalite does not employ any engineers. I'm thinking they gave some thought to the plenum and shrouding issues you mentioned.


Peace

Not writing for the OP...he's going to do this no matter and am writing
for those who might also be considering, but needing a bit of engineering
info

Fluid coupled fan clutches range from about 10% coupled (min...or
not turned on) up to 50%-60% coupled (full on) for standard duty. HD and
severe duty are about 70%-90% coupled (full on). Both also down in the
mud when turned off (about 10% coupled). The difference
between HD and Severe Duty are in the shaft bearings and retainer...if
not bigger bearings...the airplane like fan blade will wear out the
smaller bearings of the standard duty shaft bearings & retainer and
allow the fan blade to take off and punch through the radiator...been
there done that with my MGB...put on a fiberglass 9 blade and after
a few thousand miles...the water pump bearings gave out and the blade
flew through the radiator

Coupled meaning whatever from the belts (V or serpentine) multiplied
by the dia ratio between the fan clutch's pulley dia vs the dampener
pulley's dia

OEMs have been playing around with the coupling and set points. So some
OEM are not standard off the shelf (std duty, HD or Severe duty).

The electric fan clutches must be either off or on, my guess. If there
is a variable coupling, then it's going to be expensive and why guessing
digital...on or off. There might be some parasitic loading and therefore
spins the fan a bit. Guessing down in the mud like fluid coupled...5%-10%

The plenum (ducting around the radiator for the fan blade) is designed
for 'that' fan it came with from the factory

Changing even the fan blade can upset that plenum. Plus there is noise
mitigation in it's design. The Duramax had a huge problem with cooling
because their designers blew it on the plenum (ducting/shroud/etc)

There are other attributes and one key is where this OP is clueless
on. CFM is out of context without the 'head' spec for that CFM

'Head', as in restriction either/or/both negative (puller) or positive
(pusher) and in inches of water or mercury (big stuff)

Betcha the electric fan's 10,000 CFM is 'free air'...

Then the fact that most of the ones on the Flex-a-lite site for this
application has two fans. That makes it tougher to get a GOOD plenum.
There will be dead spots and if they are in the wrong places...may
create backpressure for spots on the radiator (meaning reduced air flow)

Also, note the sheetmetal for those two fans...the open area is reduced
and noodle how much LESS air flow on the highway...when even fan
clutches are turned off...

Anyone ever lift up a 1 HP (120 VAC) electric motor? Pretty heavy
and at 120 VAC, about TEN times smaller than a 12 VDC motor
that would be in any automotive radiator electric fan system. Or looking
at it the other way...a 12 VDC electric motor would be TEN times
larger than a 120 VAC motor (approx)

That is for a 12 VDC 1 HP electric fan motor. My Severe Duty fan clutch
takes +15 HP (it's rated up to 25 HP, but for the OP, kept it at it's
lower rating) and an 12 VDC 15 HP to 25 HP motor would be about +100 lbs

Also, anyone read the fine print in any of these electric radiator
fan assemblies? Hint...most don't use 12 VDC, but a bit higher. Why?
and does your TV's alternator/battery system provide that higher voltage
on a 100% duty cycle ?

Truly wish the OP would proceed with this and report back, often on
how it goes. Maybe I'm all wet and they have discovered some new
laws of physics for me to update my knowledge base and learn
something...like when the Japanese came out with air foil blades for
computer muffin fans!!! Revolutionized muffin fans. Then the swept
back blades, as they were spinning them so fast there were additional
turbulence (think jet airplane wings and why they are swept back)

You have to be careful adding electric fans in combination with clutch fans because you'll unknowingly cause turbulent restrictions in air flow over the radiator. If one is not capable of flowing the same CFM as the other then one will always be forced to suck through or blow through the other when they're both running. And if they're both rated at the same CFM then there's no point in having them back to back. Side by side is different.

transamz9 wrote:

Grit dog wrote:
Well you answered your own question. If you drive mostly empty, your fan should never really engage except really hot weather maybe. I can count on my hands how any times the fan has kicked on in my 07 unless I was towing or hauling something substantial. And my radiator fins are all smashed in thanks to my kids a few years ago!
Installing electric fans seems like a waste of time and $ for very little to no gain in a normal daily driver vehicle.

You would be surprised at how much your fan runs. If you run your A/C then your fan is constantly cycling. The OE fan is variable so you won't here it kick in 90% of the time because it only runs what is demanded of it. If this were me and I wanted to us electric fans I would just leave the OE fan in place and operating and then just add electric fans to help with the load. I would get a temp sensor rated at a higher value to add in and wire it so the OE fan will come on at a certain temp. Let the E-Fans do the light work like everyday running and A/C.

Interesting. Did not know. I thought they were free wheeling which still moves some air, or locked up. I can hear when it locks up.

I wouldn't bother, but it's your money, do what you want with it. :)

hertfordnc wrote:

wilber1 wrote:
As previously posted 1 hp equals 746 watts. 746 watts at 12v equals 62 amps. A fan using 10 hp needs 620 amps. Do the math. Try and find cables big enough to handle the amperage. Even if you can make more hp, more hp means more heat which means even more cooling required.

There's a reason they don't put electric fans on these things.

How did you get to 10 hp? THe fans draw 60 amps- so 1 hp.

THere are a lot of reasons they don't put electric fans on these things, but one upon a time they only put them on FWD rat poxes and now they try to put them on EVERYTHING. I think it will meet my needs and save me 2 mpg in my daily drive.

People re-engineer their trucks for performance, noise, or just to look ridiculous and everyone thinks that cool. I'm more interested in re-engineering for efficiency.

Flexalite claims up to 27 hp gain over stock. I thought I was being conservative. That tells me there is no way electric fans will move as much air when the going gets tough. Daily driving sure but not for towing heavy thank you.

wilber1 wrote:
As previously posted 1 hp equals 746 watts. 746 watts at 12v equals 62 amps. A fan using 10 hp needs 620 amps. Do the math. Try and find cables big enough to handle the amperage. Even if you can make more hp, more hp means more heat which means even more cooling required.

There's a reason they don't put electric fans on these things.

How did you get to 10 hp? THe fans draw 60 amps- so 1 hp.

THere are a lot of reasons they don't put electric fans on these things, but one upon a time they only put them on FWD rat poxes and now they try to put them on EVERYTHING. I think it will meet my needs and save me 2 mpg in my daily drive.

People re-engineer their trucks for performance, noise, or just to look ridiculous and everyone thinks that cool. I'm more interested in re-engineering for efficiency.

As previously posted 1 hp equals 746 watts. 746 watts at 12v equals 62 amps. A fan using 10 hp needs 620 amps. Do the math. Try and find cables big enough to handle the amperage. Even if you can make more hp, more hp means more heat which means even more cooling required.

There's a reason they don't put electric fans on these things.

Grit dog wrote:
Well you answered your own question. If you drive mostly empty, your fan should never really engage except really hot weather maybe. I can count on my hands how any times the fan has kicked on in my 07 unless I was towing or hauling something substantial. And my radiator fins are all smashed in thanks to my kids a few years ago!
Installing electric fans seems like a waste of time and $ for very little to no gain in a normal daily driver vehicle.

You would be surprised at how much your fan runs. If you run your A/C then your fan is constantly cycling. The OE fan is variable so you won't here it kick in 90% of the time because it only runs what is demanded of it. If this were me and I wanted to us electric fans I would just leave the OE fan in place and operating and then just add electric fans to help with the load. I would get a temp sensor rated at a higher value to add in and wire it so the OE fan will come on at a certain temp. Let the E-Fans do the light work like everyday running and A/C.

hertfordnc wrote:
snip...

So i may build this for less than $100 and monitor my temps with a digital OBD reader.

Please, please do this and keep us posted on how it goes...