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I am rebuilding my AC system and will do the air pump delete and clutch fan swap to electric at the same time. My question is .... How much CFM is needed through the radiator and condenser and could this be done with a single modern brushless electric fan....?
Leads onto has anyone done it?
By moving to a Trinary switch in the AC and adding a temp sensor for radiator cooling it all looks like a fairly sensible idea. Oh i will also add / replace the blue relay of doom in the center console AC switch.
Really interested in ideas, considerations etc. people have...
Cheers
David
David Martin
UK
P.s my car is a 1985 S2 Euro RHD Manual
The fan capacity needed is in the region of 3000 CFM and that requires about 30 amps current draw to drive it. Whether you do it through one fan or two is up to you but the problem is shape factor- two 12 inch fans is thus optimal and the SPAL 12 inch twin fan setup I have is probably as good as it gets [non OEM] albeit they are not brushless fans. SPAL fans are made in Italy and are used by Ferrari amongst others. My setup was introduced to replace the stock twin fan setup as my fan motor bearings were knackered.
Whether or not your alternator can support an additional 30 amp draw I have no clue and you need to determine such. You will also need some method to control the fans based on temperature of the coolant leaving the radiator- SPAL do a neat programmable controller unit. The S4 radiators have a sender in the bottom of the radiator outlet tank and that provides a modulating signal to the controller unit. The output then has PWM [pulse width modulation] to set the operating point.
The fan capacity needed is in the region of 3000 CFM and that requires about 30 amps current draw to drive it. Whether you do it through one fan or two is up to you but the problem is shape factor- two 12 inch fans is thus optimal and the SPAL 12 inch twin fan setup I have is probably as good as it gets [non OEM] albeit they are not brushless fans. ........
+1
A few of us are using the 1995-2000 Ford Contour fan (Dorman 620 -104). With minimum mods (cut off the wings) it covers the entire rad.
After the wings (tabs) are cut off the shroud dimensions are (WxHxD) = 28” x 20” x 6”
It was spec's at 3400 CFM and I have been using it since 8 years ago and > 50K miles.
I use a Flex-a-Lite 31163 (version with screwed in Temp switch)
No heating issues.
P.S. I have no affiliation with Ford, Dorman or Flex-a-Lite
electric fans make only a wind speed of around 30 km/h ( 20 miles/h ) ... so once driving above that speed they are of no use.
To cover as much radiator area as possible you want indeed 2 fans due shape as Fred says.
Also a bigger fan has a bigger motor and in that "bigger" center there is no air flow.
Last edited by belgiumbarry; 06-19-2021 at 01:36 PM.
+1
A few of us are using the 1995-2000 Ford Contour fan (Dorman 620 -104). With minimum mods (cut off the wings) it covers the entire rad.
After the wings (tabs) are cut off the shroud dimensions are (WxHxD) = 28” x 20” x 6”
It was spec's at 3400 CFM and I have been using it since 8 years ago and > 50K miles.
I use a Flex-a-Lite 31163 (version with screwed in Temp switch)
No heating issues.
P.S. I have no affiliation with Ford, Dorman or Flex-a-Lite
$80 plus little cost to ship to UK not to mention alleged 10 year warranty? Not Dorman -must be made in China but at that price does it really matter?t.
I *don't* have A/C though. The pump was seized up and so on. I live in Scotland so I wasn't too fussed.
I changed the temp sensor to a two stage one and added a couple of relays to make it all work. The only issue yet to be resolved is that the red warning light at the top of the temp gauge is now on all the time.
I like F-Dynamics fans better than Spal. Ball bearing motors and lower amp draw at same CFM. I would not switch to electric over a mechanical fan unless you need to, to make room for a supercharger for example. You can get a belt to drive your fan without the air pump. Your alternator will thank you.
good luck
Dave
electric fans make only a wind speed of around 30 km/h ( 20 miles/h ) ... so once driving above that speed they are of no use.
To cover as much radiator area as possible you want indeed 2 fans due shape as Fred says.
Also a bigger fan has a bigger motor and in that "bigger" center there is no air flow.
^^ Yes, fan AND shroud design are important. If you had 5000cfm, but in the wrong place, you would overheat.
And..Yes, fans/speed/etc..but our radiators dont get direct airflow. We're not chin breathers like say, a C5 Corvette..but not an open grille radiator either.
I would not switch to electric over a mechanical fan unless you need to, to make room for a supercharger for example.
I wish I could put in a belt driven fan on my supercharged 89. I am going to have to design a proper shroud to fit around the supercharger pulley so that I can use the A/C in traffic.
Fred,
Is this type of thing as per link below : https://www.ebay.com/itm/37091102328...0AAOSwdPJgOQAH
$80 plus little cost to ship to UK not to mention alleged 10 year warranty? Not Dorman -must be made in China but at that price does it really matter?t.
>> Yes, looks exactly like the one I am using. At the start folks were getting them from salvage yards for $25 but at such a cheap price new and warranty I went new.
" .... Do you mount these as a push (in front of condenser) or pull system (back of radiator), and is there a better aftermarket brand to go for....? David
These are meant to be 'pullers' and installed behind the rad
a fan with a shroud should always be mounted as a puller. Above that "20 m/h" it should at least conduct air in a aero way trough the fan .
Second, i'm not in favor of any shroud : above that speed all that counts is wind due road speed , so we want as much air flow as possible. Any restrictions ( shroud) will minor that.
Here is the setup i made with 2 12" fans on the rally build. Seems perfect so far , no cooling issues, i made a second one for the spare car . ( laser cut frame ) .
The value of a proper shroud is...any area the fans cant influence, is lost cooling area. A broad, deep shroud influences the entire radiator surface. And I would argue that fans are not in the way of any road air...what little we get.
I agree, that most people wont have issues losing fan airflow to 1/3 of the radiator by removing the shroud.
Our cars do not receive road air efficiently, we 'sip' air below radiator level. This is one of the large reasons under trays are important to radiator airflow as well, and they help pull air through the rad.
A healthy system will survive a lost of pieces removed from its design, for so long.
If anyone wants to fit a single fan into the early shroud so you cool all of the radiator you can use a Lincoln MK8 fan. They move well over 3000 CFM and can fit in the factory shroud with some basic aluminum spacers.
You just need to add a pwm fan controller like any of these http://www.dccontrol.com/constant_te...ontrollers.htm to properly control the later ones though. The early ones just use a basic 2 relay high/low setup.
It will pull in excess of 30 amps so you need an upgraded alt to handle it!
06-19-2021, 08:15 AM
Could you replace Two fans with one SPAL Fan?
LOL
