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Electric fan? Yea or nay?

10K views 34 replies 14 participants last post by  John533i 
#1 ·
I'm debating on going with an electric fan when I put my Graduate back together. I think it would cut down on a good bit of fan drag on the engine, especially at high RPMs since these cars don't have fan clutches.

Wiring shouldn't be tricky. A fan switch thats threaded for plugging into the engine block, relay, fuse, and right to the alternator terminal block.

What size fan should I go with if/when I put an electric fan in?

Thoughts about electric fans?
 
#2 ·
There are a lot of advantages to electric fans and I don't think I've ever heard of a disadvantage other than the possibility of electrical failure.

I believe '90 was the first year for factory electric fans and mine has dual 10" fans. They take up most of the radiator area. I suppose you might be able to squeeze a single 12" in there but I'm not sure.

Conversion kits are available if you're interested in going that direction. Here's Centerline's but I don't know anything about it myself:

https://www.centerlinealfa.com/store/1197
 
#3 ·
I've installed single 12in pusher fans on two GTVs and they are perfectly adequate on a non AC car on a 90 degree day. The fan doesn't come on very often, so it MIGHT have enough capacity with AC as well, or for Texas weather.

The original plastic fan becomes hazardous with age; getting rid of it lets the engine warm up a bit quicker, releases a few HP at higher rpm as the fan is only needed at low speeds in traffic, and makes the front part of the engine more accessible for servicing. To me it's a must.

You can buy a 12in fan from Jegs or Summit or any other speed shop; the Speedmaster brand is especially low priced. These fans all seem to come out of the same factory but the prices are all over.

The first time I used the Hayden 3647 control kit; it includes a relay, a temperature adjustment, and a probe that slips between the fan tubes. (The probe needs to be close to the water inlet on the rad). Another kit includes a threaded probe, you need to get a bung soldered into the top tank.

I used a similar Derale control kit for the second one; I was less fortunate as it turned out to be defective (once the engine hits the target temp, it cycles on and off at 1 sec intervals). Derale declined my claim for a replacement as I had purchased it more than a year before installing it.

The controller needs a power feed (I tapped the battery connection on the starter,adding an inline fuse a few inches from the connection); an ignition signal (positive on the coil) and a ground - I'll let you figure out this one :). Controller is installed near the rad on the right inner fender.

The fans are supplied with various brackets and also zip ties that attach through the rad. I went to the trouble of building custom brackets to hold the fan as I feared having the fan held by the zip ties right on the rad surface could damage the tubes or fins. I've just taken off a fan that was mounted with zip ties on my Elan rad more than a decade ago, and there was no damage of any kind. Next time I'll make my life easier.
 
#5 ·
I've been thinking about going 'electric' on my 69 1750 Spider for some time now, have read all the threads, and still have some questions:
1) I was thinking having a bung installed on my rad for a screw-in temp. sensor might be cleaner than a probe, but is it true that this type of sensor only triggers at one temp., and can't be adjusted over a range?
2) Does the probe system (with adjustability) making contact with bottom? of the rad on the fins actually work reliably?
3) Can I just buy any, say, 12" puller fan and the wiring is the same on each - just power and ground? and go from there with the other components?
Thanks!
 
#6 ·
I've been thinking about going 'electric' on my 69 1750 Spider for some time now, have read all the threads, and still have some questions:
1) I was thinking having a bung installed on my rad for a screw-in temp. sensor might be cleaner than a probe, but is it true that this type of sensor only triggers at one temp., and can't be adjusted over a range?
2) Does the probe system (with adjustability) making contact with bottom? of the rad on the fins actually work reliably?
3) Can I just buy any, say, 12" puller fan and the wiring is the same on each - just power and ground? and go from there with the other components?
Thanks!

I'm wondering what kind of sensor some of these kits may be using. If its a radiator temp sensor, it can't be nearly as accurate as one that threads into the engine block.

Centerline's Kit includes a pressure bulb temperature switch that I'm assuming attaches to the radiator.




Jegs has a kit that would thread into the engine block that just provides an on/off grounding to the engine block, which is the same sort of switch that will trigger the overheat warning light in most cars. I'm assuming it would thread into the engine block somewhere.
JEGS Performance Products 10560, JEGS Electric Fan Wiring Harness Kits | JEGS Performance Products



There are a few unused plugs in the late model 2 liter engine. I might give mine a bit of a lookover since its hanging on a hoist at the moment and examine where I might be able to put a temperature switch in the block.
 
#7 · (Edited)
OK, I just installed an electric fan on my 86. Here's the stitch.

A 12" fan wont fit due to the radiator core support and the way the radiator sits in there. If you want the fan to sit up against the radiator (and you do!), A 10" fan will fit.

I installed mine as a pusher. I already spent good money on the 12", so I bought a cheaper 10". I think it's a 650cfm fan.

It doesn't cool the car very well at all. As you would guess when you think about it, it blocks air flow to the front. Then when it comes on, it can't cool the engine past a certain point, and the hi temp light comes on. I have a great radiator...it cooled just fine before I installed the electric!

I'm going to try a higher cfm fan, then if it doesn't cool as well as the stock, i'm going back to stock. The seat of the pants dyno can't really tell if the reduced drag is there, so...

Good luck!

FYI your radiator has a bung on the bottom left; you can use the temp sender from a GTV6 from Centerline or any others. It's cheap and gives the signal to come on at 180 or so.
 
#8 ·
Yeah, 10" sounds to me like it would be too small. I think if a 12" fan doesn't fit, I might could make it fit.

I need to measure the radiator in my Spider and see if I could get a 12" puling fan in there.

I found one on Amazon that has a CFM rating of 1730CFM for the 12" fan and 1000 for the 10" fan. Sounds like your issue might be with the size of the fan.
 
#12 ·
12" fan fits perfect between the top and bottom tanks of the radiator itself. Then when you go to mount the radiator in the car, the fan housing will interfere with the core support, and the radiator won't tilt back to where it's supposed to be. I found another thread where the guy had the same issue...If you end up moving the fan down to partially overlap the bottom tank, then you won't be able to push the radiator down in the support.

There's a chance that the core supports are different between an early S3 and a later S3; then hey- use a 12"!
 
#9 · (Edited)
Put mine in the front of the radiator, unless you have A/C , just used a 10amp fuse. Don't buy all that JUNK these guys recommend, waste of $. Mines a 12" My radiator had the port for the sensor and just bought one for a FETTA, GTV-6 or Milano or any other European car. Sensor goes to ground and to the fan, power to the fan used the connector were the alternator hooks up on the passenger fender. It's been working for over 15 years. Get rid of that PLASTIC P.O.S. It may be original, but it's a engineering mistake and should be fixed! Plus it makes for easier access to the motor. You'll see the 1" Brass nut on the bottom of the radiator on the bottom on the passenger side to install the sensor.
 
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#10 ·
It's a great mod. 5-7 hp boost, and the fan can spin quickly when you're sitting in traffic - more effective cooling.

Mount the switch in the radiator, not the block. If you look closely, in the sheet metal at the base of the radiator, you'll see a little half moon recession. That's where you want to install the bung in the radiator for the switch.

I mount pusher fans in front of the radiator. You can do a water pump without having to remove the radiator.

bs
 
#13 ·
I'm thinking about installing it as a pulling fan rather than a pusher. I'm thinking it might make for an easier installation and definitely easier to put in a 12"

I measured the radiator supports and the backside of the radiator in the shop today and unless theres something I'm not taking not account, I think it will accommodate the dimensions of the 12" fan from Centerline.
 
#17 ·
Here's a pic of a 12 in fan mounted as a pusher in front of the AC condenser. It's a tight fit. I've got it mounted with the through-fin plastic ties. It's loud, but has managed to work well here in FL. I don't do a lot of traffic driving with the AC on, that would probably stress the system. I also upgraded my alternator after installing it, though the old one did ok.
 

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#18 ·
That's pretty wild that it still cools the radiator after having to pass through the condenser, also! I don't have a condenser, so the 12" fan frame interferes with the core support; yours doesn't as it's outside of the core support.

I have a new 10" higher CFM fan on the way. The wimpy one I picked up locally is pretty lame.
 
#20 ·
Just went electric on my 86 Spider with A/C. Been through three plastic fans in 30+ years of ownership and had enough.

First, thanks to John533i for his help. The S3 with a/c is a different beast and you will not have the options others discuss on this board for different models. He saved me a lot of trouble by making this clear in his posts. I went with an 11" medium profile Spal puller fan (model 30101512). That 11 incher can be hard to find but pulls 1200 CFM of air, significantly more than the 10" low profile Spal fan. You will have to mount it off to the side to avoid the water pump, but I noticed that the Centerline kit has to be mounted that way, so I assumed it would be okay. The 11" fan has more of an open frame that allows you to mount the fan in a variety of positions to avoid the pulley. I attached the fan using the top drivers side shroud bolt and ran a piece of strip metal between the two lower shroud bolts. That creats a diagnonally canted bottom bracket that aligned perfectly with mounting points on the bottom of the fan. The resulting three point connection (shroud bolt on top, two holes through the metal strip on bottom) is plenty secure and the fan sits tight to the rad. Use threadlocker or locking nuts to assure that it stays there

I used the Spal 185 deg temp sensor and wiring harness, which came in a kit. Quality gear here, and no reason to skimp on the component that makes it all work. The sensor screwed right into a pre-installed bung in my rad. The Spal instructions say not to use teflon tape, from which I assumed I could not use thread sealant of any kind. Not true. I had to go back in and seal it off after finding a drip and checking with Spal (great tech help there, by the way). The 3/8" sensor fits inside a 1/2" NPT adapter that was a direct fit into my rad. HOWEVER, the sensor is designed so that it does not screw all the way in to the adapter. You need to use a sparing dose of high temp thread sealer or it WILL leak (I used Permatex). I went belt and suspenders by also running a bead of Permatex gasket maker around the outside of where the adapter meets the rad, and where the sensor enters the adapter. Took power off the alternator junction on the driver side fender well rather than running to the battery in the trunk and was able to wire everything up very easily.

Duke58 has the gospel thread on how to get an S3 refilled with coolant. Follow it exactly and you'll be fine. My fan runs great and cycles on and off flawlessly. Will cool the rad at idle in just a few seconds in 85 degree ambient temps. Engine temp stays steady at highway speed as one would suspect. Highly recommend this modification. I can't say for sure there is a power gain, but I can say for sure that I feel a lot better about revving high now that I don't worry if a fan blade is about to fly through the rad (or hood). Fan and harness around $100. About 3-4 hours of fiddling around to get it all mounted and situated properly.
 
#22 ·
Didn't want photo evidence of all my mistakes, so didn't take pictures as I went! But here is one of it all back together, for whatever it's worth. You can at least see the top left of the fan attached to the top left shroud bolt (shown as bottom right in this photo because it was shot from the front of the car looking down). You can also see how the Spal fan housing is too thick to mount in front of the water pump, but that the open frame on this model allows you to offset it when mounting. May also be able to make out how much larger these blades are than the 10" low profile Spal fan because of the "thicker" profile of the fan. This is why it moves so much more CFM. You can also see my shiny new water pump sans the "bound-to-fail-again" plastic fan.
 

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#23 ·
Good job. Do you still have the spacer on the nose of the water pump? you had better pull that off before it flys off, like mine did! It was stuck pretty tightly, so I thought that it was part of the pulley. Until it wasn't LOL. If I ever want to attach a fan again, I would have to source a spacer...
 
#25 ·
Uhh, spacer? What spacer? I thought the protrusion of the end of the water pump pulley was fixed. Is it removable? How? Do I have to take the pump off to remove it? As an aside, the 11" Spal fan will fit fine if that protrusion is removable. It only overlaps that by 1/4" as it is. I might center the fan up just to be tidy if that's removable.
 
#26 ·
I thought mine was fixed, but I wasn't sure. I tried to pry it off with a screwdriver and hammer, but it didn't seem to be budging so I left it, thinking it was one piece. When it came off , I saw that the mating surface between it and the pulley had lots of corrosion. It may have been a 'dissimilar metals' type thing, where they weld themselves together over time. I would put the bolts to the fan back in to secure it, and torque to spec, if there is one...
 
#28 ·
It knocked on something; not sure what, but no dents. I heard a smack under the hood while engine braking around a corner in a neighborhood, basically. I found the issue a few minutes later when I pulled into a friend's driveway and looked under the hood. I went back later on to find it, never did.
 
#29 ·
I have no appetite to undo this job to pry it off, so I'll nut it down and forget about it until the next time I have it all apart. Somebody like Spruell or Centerline ought to offer a water pump with that spacer removed for those of us who have converted to electric fans. They could charge $20 more and call it a "custom conversion."
 
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