CFM of radiator fan?

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keehn
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Joined: Tue Oct 01, 2019 5:14 pm
Location: Martinsburg, WV

CFM of radiator fan?

Post by keehn » Wed Oct 02, 2019 5:46 pm

Hello everyone,

My first tech question in over a decade: Does anyone know the CFM rating of the radiator fan?

I'm asking because I'm thinking of deleting the pulley fan in favor of an electric version, in addition with an E28 radiator.

Thanks!

Mike

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dsw99a
Posts: 68
Joined: Thu Jul 30, 2015 1:32 am
Location: Hawaii

Re: CFM of radiator fan?

Post by dsw99a » Thu Oct 03, 2019 1:59 am

That sound interesting. Let us know how it all works out.

PatinaBeforePolish
Posts: 224
Joined: Sun Jan 18, 2015 1:22 pm
Location: Baltimore, Md.

Re: CFM of radiator fan?

Post by PatinaBeforePolish » Thu Oct 03, 2019 5:38 am

keehn wrote:
Wed Oct 02, 2019 5:46 pm
Hello everyone,

My first tech question in over a decade: Does anyone know the CFM rating of the radiator fan?

I'm asking because I'm thinking of deleting the pulley fan in favor of an electric version, in addition with an E28 radiator.

Thanks!

Mike
I did this on my 78 F150 (hey it’s a straight six) using the stock radiator and it worked out well. Did it for safety reasons, was convinced I lop off a finger or two at some point. The old lump actually felt a tad more spritely no longer having to spin a 2 lb steel fan. I think with a BMW you’ll need to give some thought as to where the sensor switch is located or use an existing one as temps vary by location.
78 F150
79 528i
81 528i parts car
01 540i
86 944
08 X3 don’t judge me it’s there to preserve the others

keehn
Posts: 7
Joined: Tue Oct 01, 2019 5:14 pm
Location: Martinsburg, WV

Re: CFM of radiator fan?

Post by keehn » Thu Oct 03, 2019 4:57 pm

Belt-driven fans on any engine always suck away horsepower. For example, my diesel class A RV fan robs 20 HP alone!

As for the sensor, I plan to use the existing equipment, but I'll have to get the high/low resistance readings of the sensor during normal operating temperatures and either get a temp-controlled fan switch, or rig up a home-brew Arduino/power relay box that will give me far more control (and monitoring) of the fans operation.

onovakind67
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Joined: Mon Sep 20, 2010 9:45 am
Location: Fairfield, CA

Re: CFM of radiator fan?

Post by onovakind67 » Thu Oct 03, 2019 6:43 pm

I deleted my mechanical fan many years ago on my E3. I use the 64541392913 2-speed auxiliary fan from E32's or E34's as a pusher fan. I use a Volvo 2-speed fan control relay triggered by a BMW 90°/99°dual thermoswitch. As long as the car is moving 35 mph or so the fan never comes on. If I'm stuck at a light or in traffic, low speed is energized and that is sufficient to cool it down.
'72 3.5L 5-spd Bavarious - E3 with E12 front struts/brakes, E28 3.25 LSD rear axle, E39 wheels, Webers, etc, etc, etc...

PatinaBeforePolish
Posts: 224
Joined: Sun Jan 18, 2015 1:22 pm
Location: Baltimore, Md.

Re: CFM of radiator fan?

Post by PatinaBeforePolish » Thu Oct 03, 2019 6:45 pm

I used a Spal purchased from Summit. They have a nice selection and also carry a wiring kit with relay - made the install much easier. Included in the instructions are how to add a switch for manual operation.

https://www.summitracing.com/search/pro ... ric%20Fans
78 F150
79 528i
81 528i parts car
01 540i
86 944
08 X3 don’t judge me it’s there to preserve the others

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Joe Boston
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Joined: Sun Nov 27, 2016 12:11 pm
Location: Winchester, MA

Re: CFM of radiator fan?

Post by Joe Boston » Thu Oct 03, 2019 8:32 pm

very interesting the electric fan modification...
if you can post some pictures of your auxiliary fan, did you guys use a reversible fan and mounted it in the back of radiator?
1980 E12 Ascatgrau 5 speed
2001 E38 740 Black
2012 F12 650 IC black

onovakind67
Posts: 78
Joined: Mon Sep 20, 2010 9:45 am
Location: Fairfield, CA

Re: CFM of radiator fan?

Post by onovakind67 » Thu Oct 03, 2019 11:00 pm

Joe Boston wrote:
Thu Oct 03, 2019 8:32 pm
very interesting the electric fan modification...
if you can post some pictures of your auxiliary fan, did you guys use a reversible fan and mounted it in the back of radiator?
The BMW 64541392913 2-speed auxiliary fan is built as a pusher and is mounted in front of the radiator in its stock configuration. It mounts on three steel straps and is sealed to the front of the radiator.
'72 3.5L 5-spd Bavarious - E3 with E12 front struts/brakes, E28 3.25 LSD rear axle, E39 wheels, Webers, etc, etc, etc...

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