Cooling fan shootout - Engine Masters

[GuysMonteSS]

My question is simple, what are some of you guys using for your cooling fan set-up?

I have owned my Big Block powered 1986 Monte Carlo SS for 20 years now.
It has a 4 core brass rad,5 blade stock clutch type fan,180 degree Milodon High Flow thermostat,Black Mountain cog pulley kit,and a full stock rad shroud.
I have also used the stock cast iron water pump and a Weiand High Flow aluminum pump,but I did not notice any difference between the two pumps.
Even on our hottest summer days and on long highway trips,my Monte has never run hot and the clutch fan rarely comes on.
I live in a rural area,so around town driving is very limited,but what city driving I have done has also been trouble free.
Hope this helps.
Guy

[BOOT]

Crazy to think the flex fan is supposed to be a gift from the cooling gods yet it’s literally the worst option next to a fixed fan of any type. Think of how many hot rods there are out there running these things, yet the data looks the same on every test. Flex fans are power hungry!

They move a lot of air at low rpm and If you limit them(underdrive) the top end HP loss is not so bad. Any full mech fan will eat a lot of HP if you spin it up. This test just kinda shows what mech fan design is more efficient/effective at moving air.

[Lizardracing]

An overheated engine makes 0hp....js

[BOOT]

My car got up to 170's with the old setup in summer, may have to adjust or even underdrive a bit more once I get the new setup going.

[rfoll]

On a similar thread, someone suggested that the clutch fan is helped by the air pushing through the radiator, lessening the parasitic loss.

Yes, No, Maybe. Fans are there to create a low pressure area behind the radiator to assist speed generated air pressure.

FWIW, in a vehicle I knew well, removing the engine driven fan raised the 65 MPH cruise coolant temperature 10 - 15 degrees. The theory that highway speed air pressure is enough depends totally on all the elements of styling, air flow, fan shrouding, engine compartment space and underbody design, to name a few.

The point was the parasitic loss should decrease with road speed. You have to wonder what the parasitic loss is driving an alternator to run a powerful electric fan. No one mentioned noise. Generally speaking, the thermostatic clutch fans are quiet. I have them on everything and never have to listen to them. I had one freeze up the bearings while driving once and was alerted immediately by the fan noise at 60 mph.

[BOOT]

You have to wonder what the parasitic loss is driving an alternator to run a powerful electric fan.

I know your talking bout something else but I'm stealing your point to make another.

Mechanical energy converted to electrical and then back to mechanical, there are losses at each step and no alternator is 100% efficient.

Still then there is the argument a mech fan always needs to be accelerated and an e-fan can be shut off.

[rfoll]

https://portland.craigslist.org/mlt/pts ... 35773.html Maybe some fan of electric fans wants to buy my fan.

[Ken_Parkman]

Problem is a mechanical fan is engine driven, and engine rpm is not particularly related to the cooling requirements.

So you have to have the fan effective for your worst case cooling condition, and it may be wildly wrong for the best case cooling condition. A fan designed to work at hot idle in a traffic jam is insanely wrong at 6000 rpm, and eats an equivalent insane amount of power. Air power is a cube of rpm delta, so 6000 rpm takes 216 times the power a fan takes at 1000 rpm. This is why you sometimes get these nutty power draw requirements unrelated to cooling requirements.

This is also why an electric fan on a thermostat is in general so much better as it is activated by the actual cooling requirement, and is not driven way outside of it's design point. You do not have the cube problem above.

But an electric fan is also not a no brainer - there are so many variables. including natural flow through the rad. A nicely shrouded fan effective at low condition may create an excessive restriction at highway speeds. Been there done that.

[blackford]

I'm sorry, but am I the only one who thinks that 30 HP to turn a fan is absurd? So, I would need to take a very powerful 30 HP electric motor that spins the fan up to speed (either directly or by gearing it up) to move the same amount of air as the same fan being spun by an engine? Does that seem reasonable to anyone?

[dannobee]

I wouldn't call 30hp unreasonable. High, but certainly within the plausible range.

Don't try to compare the volume of air moved by the electric fans on a modern car to the volume of air moved by an engine driven fan. The engine driven fan can move an absolutely huge amount of air in comparison.

As a test, with the hood up on your front wheel drive car, turn on the A/C to get the electric fan moving and put your hand behind the fan to check volume. Then do the same on the engine driven fan on whatever you use to tow your race car or boat and rev it up to an engine speed you see going down the freeway or up a hill.

[Tuner]

I'm sorry, but am I the only one who thinks that 30 HP to turn a fan is absurd? So, I would need to take a very powerful 30 HP electric motor that spins the fan up to speed (either directly or by gearing it up) to move the same amount of air as the same fan being spun by an engine? Does that seem reasonable to anyone?

Not reasonable at all, 30 HP is just nuts, yellow journalism. 30 HP = 22371 Watts / 12 V = 1,864.25 Amps. Who wants to try again?

Once upon a time on a chassis dyno on a hot summer day with a 355 SBC short-track car that had no fan at all it started getting warmer than ideal with just a 110V squirrel cage fan blowing at it so we put one of those molded black plastic fans on it about 12"-14" diameter and it did not change the RWHP at all but it did cool the engine just fine so we left it on and made a shroud out of one of the shop's Rubbermaid trash cans that serendipitously was the perfect size, length and diameter, when cut short and attached with tranny cooler zip ties through the heater core and the lip of the trash can.

[Rick!]

I'm sorry, but am I the only one who thinks that 30 HP to turn a fan is absurd? So, I would need to take a very powerful 30 HP electric motor that spins the fan up to speed (either directly or by gearing it up) to move the same amount of air as the same fan being spun by an engine? Does that seem reasonable to anyone?

Not reasonable at all, 30 HP is just nuts, yellow journalism. 30 HP = 22371 Watts / 12 V = 1,864.25 Amps. Who wants to try again?

Once upon a time on a chassis dyno on a hot summer day with a 355 SBC short-track car that had no fan at all it started getting warmer than ideal with just a 110V squirrel cage fan blowing at it so we put one of those molded black plastic fans on it about 12"-14" diameter and it did not change the RWHP at all but it did cool the engine just fine so we left it on and made a shroud out of one of the shop's Rubbermaid trash cans that serendipitously was the perfect size, length and diameter, when cut short and attached with tranny cooler zip ties through the heater core and the lip of the trash can.

The fans I spec out for 400+ hp diesels eat 50hp easily. 600+ hp engines eat even more. But, they need to operate at 47C ambient at full song at 2 Bar boost until they run out of fuel... Pretty sure there ain't no 16" fan that puts out 13,000cfm but Rob doesn't need to worry about that.

Sounds like the "study" created poor data. Whoda thunk that?

I did have a magical fan around here that cooled awesome and took nothing to turn it. I borrowed it to Sasquatch and that sumbitch gave it to Nessie who lent it to a martian so I have no clue how to get it back...

[Tuner]

I'm sorry, but am I the only one who thinks that 30 HP to turn a fan is absurd? So, I would need to take a very powerful 30 HP electric motor that spins the fan up to speed (either directly or by gearing it up) to move the same amount of air as the same fan being spun by an engine? Does that seem reasonable to anyone?

Not reasonable at all, 30 HP is just nuts, yellow journalism. 30 HP = 22371 Watts / 12 V = 1,864.25 Amps. Who wants to try again?

Once upon a time on a chassis dyno on a hot summer day with a 355 SBC short-track car that had no fan at all it started getting warmer than ideal with just a 110V squirrel cage fan blowing at it so we put one of those molded black plastic fans on it about 12"-14" diameter and it did not change the RWHP at all but it did cool the engine just fine so we left it on and made a shroud out of one of the shop's Rubbermaid trash cans that serendipitously was the perfect size, length and diameter, when cut short and attached with tranny cooler zip ties through the heater core and the lip of the trash can.

The fans I spec out for 400+ hp diesels eat 50hp easily. 600+ hp engines eat even more. But, they need to operate at 47C ambient at full song at 2 Bar boost until they run out of fuel... Pretty sure there ain't no 16" fan that puts out 13,000cfm but Rob doesn't need to worry about that.

Sounds like the "study" created poor data. Whoda thunk that?

I did have a magical fan around here that cooled awesome and took nothing to turn it. I borrowed it to Sasquatch and that sumbitch gave it to Nessie who lent it to a martian so I have no clue how to get it back...

Your story is BS, martians don't need a fan because everybody knows it is so cold on Mars.

What drives the 50 HP fan, how many belts and what size?

[n2omike]

Actual Dyno Test. Engine Masters. Very interesting. They are very good at doing valid dyno tests. Also tested water pump parasitic drag. The FULL videos are on the Motortrend App, but the links below give the results.
Videos are short and to the point.

https://www.youtube.com/watch?v=Hz0ebc6XkFE&t=10s

Using/Not using a shroud made a significant difference in horsepower. Explanation below.

https://www.youtube.com/watch?v=Os_Hna9DZa8

[Tuner]

You really think 30 HP + the water pump through a 3/8" V belt?