Electric engine help needed (FE related)

[AlanCasida]

I am looking at putting an electric cooling fan(s)in my 65 Mustang but I have no clue on what CFM to shoot for. I have a Griffin 2x1.5" crossflow radiator. I will be running my 452" FE motor that will hopefully see 550-600hp at some point. I am also planning on running in Dragweek next year so it will see some street use. Any insight from you guys will be greatly appreciated.

[My427stang]

The most you can get LOL

Seriously, I'd say 4000 cfm would be the bottom line if rated from a reputable manufacturer, more is better.

If you can make the room, Lincoln & Taurus fans supposedly work real well. 

The real key though to a tight FE engine bay is an equal or better path outwards.  Whether its lots of room around the motor, or up through the hood.  If you don't have exit airflow, they like to get hot

[jayb]

I've fought with electric fans for years, and learned a lot in the process.  One thing I've learned is that most cfm ratings are meaningless.  This is because along with cfm, you need to specify a pressure drop across the fan.  This is the same as with flowing ports on a flow bench; the flow numbers are meaningless unless you specify the pressure drop.  Fortunately, on flow benches just about everyone uses 28" of water for the pressure drop.  This is pretty standard for SuperFlow benches.  However, I've seen some pretty optimistic data presented that turned out to be with 25" of water for the pressure drop.  Probably valid data, but no good for comparison with data collected at 28" of water.

As far as I know, there is only one company that gives this kind of data with their electric fans.  That is Spal.  Here is a link to one of their technical documents on one of their fans.  At the bottom you can see how the cfm rating changes with pressure drop:

http://www.spalusa.com/pdf/30102054_SPEC.PDF#view=FitH

You will NOT have zero pressure drop in the car, so that 2000 cfm Flexalite fan won't flow anywhere near that much once you install it.  My experiments with one of those Black Magic fans and a Spal fan with a much lower cfm rating showed that the Spal fan was far superior; my guess is that due to blade design or motor capacity the cfm of the Black Magic fan dropped off dramatically when the fan was loaded with a pressure drop.

Another thing I've learned is that puller fans are much more efficient than pushers.  Sometimes a pusher is required due to space limitations, but if you can use a puller or two you are much better off.

Finally, make sure your electrical system is capable of delivering the power necessary to run the fans.  This means 30 amp fan relays and #10 or #12 wires for fan power.  I usually get the Painless Wiring relay kits, which include a 30 amp circuit breaker rather than a fuse, and the correct size wiring.

On my Mach 1 I have two Spal fans, one 12" puller and one 12" pusher.  I have limited experience with these fans on the existing engine, but with the supercharged engine they kept the car very cool, so I don't think I will have any problems with the new motor.  Also, I have 2 12" Spal pullers on the Shelby clone, and had no cooling issues last year on the road or track at Drag Week.

Hope that helps, Alan, and with luck I'll see you at Drag Week next year LOL!

[amdscooter]

I'll add my2c. I had previously tried 2ea. 10" flexalite shrouded puller fans on my stock 390 Fairlane without success. I used 2 small fans as opposed to one large due to space issues with the water pump pulley. With 2 smaller fans the pulley sat between the fan motors. With a 180f trigger the two smaller fans simply could not keep up on 85f+ days and the temps would climb. I ended up going back to the stock fan/clutch setup.


Good Luck!