electric fans
Le Mans Master
Joined: Feb 1999
Posts: 6,807
Likes: 0
From: Hoosier
Cruise-In III Veteran
I'm using the dual Spals. There is a slight performance and efficiency improvement because the engine is not dealing with the fan on crank. I don't know how mearsurable it is.
Yes, it's a good idea to increase the alternator output to match the higher amp draw from the fans.
The good thing is that the amp draw is only at stop light driving and not needed at 35-40 mph or more.
If you're cooling OK with your clutch fan, you'll probably not realize any serious performance and cooling improvements.
Yes, it's a good idea to increase the alternator output to match the higher amp draw from the fans.
The good thing is that the amp draw is only at stop light driving and not needed at 35-40 mph or more.
If you're cooling OK with your clutch fan, you'll probably not realize any serious performance and cooling improvements.
Race Director
Joined: Nov 1999
Posts: 10,643
Likes: 8
From: Foxfield CO 1970 Convertible
Another advantage is that electric fans can pull their rated cfm through the radiator when the engine needs it most - in stop and go traffic or idling. Mech fans are barely turning during these times and pull their max when the engine is revved up - like when the car is moving at high speed and the fan isn't even needed... 
Race Director
Joined: Sep 2002
Posts: 10,362
Likes: 5
From: San Diego - Deep Within The State of CONFUSION!
Originally Posted by AlwaysWave
I'm using the dual Spals. There is a slight performance and efficiency improvement because the engine is not dealing with the fan on crank. I don't know how mearsurable it is.
Yes, it's a good idea to increase the alternator output to match the higher amp draw from the fans.
The good thing is that the amp draw is only at stop light driving and not needed at 35-40 mph or more.
If you're cooling OK with your clutch fan, you'll probably not realize any serious performance and cooling improvements.
Yes, it's a good idea to increase the alternator output to match the higher amp draw from the fans.
The good thing is that the amp draw is only at stop light driving and not needed at 35-40 mph or more.
If you're cooling OK with your clutch fan, you'll probably not realize any serious performance and cooling improvements.
Yep like he said 
I have dual Spals too. I had to upgrade the alternator, so I know the alt is working harder, robbing more power than normal from the engine. But I cannot beleive for a second that the alternator is pulling the engine down more than or equal to, the OEM fan/Shroud combo.
Big bennie that I have is performance and mileage because of the lower engine temp. I ran 205 before, even though my fan clutch and radiator were fine. 210 or more easy with the A/C on. And the engine always ran doggy when it was that hot. Very poor gas mileage too.
Now I run 180* no matter how long I drive it, whether the A/C is on or not. And it runs like it is SUPPOSED to now, even after driving for a long time. I think that my gas mileage is better now because it is running better, not because of the fan change. I could be wrong ... heck it may be a nice combination of both.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
I am running a single Spal fan with a new controller from Spal. I did upgrade the internals of my alternater to 80 amps. Very easy to do at a small cost. The big advantage for me is the extra room. I was able to put in the VBP spreader bar and get rid of the fan and shroud. Much cleaner install. I can't say there was any HP increase but I got rid of that big fan.
Drifting
Joined: Nov 2001
Posts: 1,469
Likes: 6
From: 68 427 4.11s Roadster
There are 2 faults with the reasoning above.
This is also the point the alternator is spinning the slowest and may not be developing power. But it is easily fixed. But its not a great selling point!
They weren't added for high speed use but for idle and low speed, of course they pull their rated cfm at idle. Also they have clutches on them , they're off too.
I kind of doubt the starter even notices the fan spinning at a few hundred rpm.
The good thing is that the amp draw is only at stop light driving and not needed at 35-40 mph or more.
Mech fans are barely turning during these times and pull their max when the engine is revved up - like when the car is moving at high speed and the fan isn't even needed
I kind of doubt the starter even notices the fan spinning at a few hundred rpm.
