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I have a 1984 Spider, and am restoring a 1974 GTV 2000; I've heard that replacing the engine-driven fan with an electric one, can give up to 5 HP increase in power. Down side: I've heard that can use up to 5 Amps, and some fan sites say up to 13Amps. Almost think I would then need a new alternator on my 1974 GTV. IAP and other aftermarket suppliers seem to have easy electric fans, but I've heard that european companies like SPAL have quieter and more efficient fans. Anyone have experience with electric fans, i.e., what fan would use the least amps, give you the proper cubic feet-per-minute (cfm)? I've heard that 2,000 cfm would be good for my Spider and GTV? Also, what size fan? Any help would be appreciated. Thanks.
 

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Well, I've done a fair amount of research on this, and have kept my eye open whenever the subject comes up. One day I might even get around to doing it myself...

So, what I've heard:

The 5hp increase is probably overstated. Or, maybe you use nearly that much, but only at the high end of the RPM range... most of the time it's much less. So don't expect a very noticable kick in the pants increase. One thing you do gain, is less fan noise, letting you hear the mechanical music of the motor a bit clearer, and a little quieter when cruising down the hiway.

I don't remember a proper CFM number, might have been under 2000, but you need to research that. I'd think IAP and Centerline's fans would be a good starting point, if they say the capacity. Remember, they have to clear the engine, pulley, and whatever else might be in the way. Search around on the BB and elsewhere, too... Hope some discussion comes up on this, would be good to get opinions on the latest choices out there...

Amount of current... There was a thread about "what do you lose more with, the mech fan, or the electric, in alternator draw?", but I know that you wouldn't lose much with an electric. (12V X 13A=156W, 156W/768= 1/5 to 1/4HP)

Is your charging system up to 5-10 or more extra amps? That's another question. 74, you probably have the same Bosch 45A alternator that I had stock (77). I just replaced mine, due to shot brushes and commutator. Got a rebuilt 90's one, you get 70A, and an internal solid state regulator, for $81 without the core charge. (Kragen) If you have a stock setup, no massive radio, or bigger headlights, etc... I'd think the stock 45A would be OK... If not... it's probably a worthy upgrade for everything else, as well as the fans that will only come on now and then.

HTH...

Jon
 

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Check out the Permacool website. Their fans seem to move the most air of the American manufacturers and they have dimensional and flow data for each size fan. Notice the difference in flow rates between curved and straight bladed fans. I believe the 12 and 14 inch fans draw 6 amps.
 

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I replaced the mechanical fans with electric pushers on my 74 GTV, my 79 spider and my previously owned 73 GTV. There is lots of room to install a pusher on a GTV. Space is tight on a spider. I have no idea what brand is on my GTV. I bought it on ebay based upon size and price. My spider has an A/C fan from a series 3 spider. It is attached with cable ties. I have had no problems with cooling or electrical load. GTV's tend to run cooler than spiders because the airflow to the radiator is less obstructed. In my opinion, the biggest benefit from replacing the mechanical fan is all the extra space around the front of the engine that makes some maintenance jobs a lot easier. There is also less load on the water pump bearing.
Ed Prytherch, Columbia SC
74 GTV
79 Spider
82 Spider parts car
88 Milano Verde
 

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I put on a front mounted pusher I got at the local kragon
on my 72 spider.
I seem to run cooler now then I did before.
way way way quiter
better MPG as the old fan was pulling a lot on the freeway.
on the freeway after you are up to speed it will only take about 10hp-20hp
so if the fan is even sucking 1hp that is a big percentage of the used power.
my fan kicks on when the motor temp get a few ° over normal. I think I set if for 5° over and to stop at 0° over normal.
 

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I've been using the IAP pusher fan kit with thermoswitch for about three years. It works fine and I like not having the fan in the way when working under the hood. Does it give me horsepower? Hard to say because it went at the same time as a much-modified motor.

I later learned something helpful from a radiator guy, who saw the installation. The kit comes with plastic straps that attach the fan by fitting though the radiator. He says it's better not to use them. Seems these little buggers, with their serrated teeth, can saw through the radiator if they're not on really, really tight.
 

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Another reason for the swap which no one has mentioned is that the mechanical fan is turning fastest when you are going fast. You don't really need the fan then, as air is flowing through just on account of your speed. My electrical fans, both on my Alfetta which came with them, and my GTV, which I installed, only seem to come on when I'm stuck in traffic going slow, so any power they are robbing electrically isn't happening when I need it high up in the power curve. So the fan swap is a good idea.

Now the switch to control the fan is another topic that interested me. I didn't quite like the kit switch that either fits in the radiator fins or snakes out of the rubber hose at the hose clamp. I found a nice solution years ago that I implemented and is working great. It involves finding a radiator fan switch housing off of a Saab Turbo. In the housing, you install an Alfetta in-radiator temp swich, and put the whole thing inline in your lower radiator hose. I wrote an article for our local Alfa club here in the bay area years ago on it. I'll attach the article and here are the pictures.
 

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The Saab unit is set for 115/110 C, but that is in the upper radiator hose where the temps are hotter and it's for a Turbo car, so I don't know the requirements there. It is the same thread size as the Afetta in-radiator switch which is 85/80 C, so I put one of those in, especially since I was mounting it to the lower radiator hose.
 

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There are several (perhaps too many) threads that approach this subject, both discussing theory and actual experience. Certainly it sounds like a good upgrade, but I tried it without mixing any other upgrades, and never experienced the much anticipated hp gain. Here's is one thread titled "Installing electric fan", and in particular note post 11. Then also see the thread "saggy motor mounts=exploding fan and shroud". My post is number 30.

Best regards,
 

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I can't attest to any horsepower claims, I do think that just turning the fan on when needed is a good idea. In the early days the electrical method wasn't economic, or practical, or whatever, but they just did it mechanically in those days. Every car is electrical these days. Some like the originality, and that's fine too.

Regarding the complexity of the installation as in your post 30, I don't know what problems your mechanic ran into with your kit, you didn't outline what it was. I put mine in less than 1/2 hour and I'm not a mechanic. My mechanics have seen my installation and say it's fine, so I didn't do anything "shade tree". On my GTV I put it on the front, as a pusher, which requires removing the grill, more work than making it a puller.
 

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I think mine went on much quicker then. bolting on the old fan. and I did not get bloody like I did every time I worked on the old fan.
 
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