Do I need to upgrade my alternator with these fans?

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evans68cuda

evans68cuda

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Hey guys, the cuda is ready for the road now! But before I take it out too far, I need to address the cooling system. I’ve got aluminum 26” radiator with a 17” clutch fan. I’ve let it sit for about 15-20 min running while I tuned on the carb and set the timing, and in that time got it to 210 degrees so I shut it off. This is going to be my daily and being in Santa Cruz county, traffic is a big concern so I would rather be safe than sorry here. I’ve heard good things about the ford contour dual fan setup and would really like to go that route, but not sure my alternator would be able to handle it. I’ve got the 70+ 60 Amp system and am using a 8 awg from the alternator directly to the battery, and the MAD bypass. Ive got an MSD 6al box, a heater, and plan on installing my 4 125 watt speakers. I plan on just running the speakers to the head unit and no subwoofer, so should be a low amp draw. My concern is will the 60 amp alternator be able to support the fans? No AC, elective fuel pump, or crazy sound system. I’ve read of guys on here running msd, electric fuel pumps and electric fans on the 60 amp alternator, but wasn’t sure of how many amps their fans pulled. I’ve heard the contour fans pull 40 amp at startup and go down from there. Thanks guys! Oh and it’s a mild 340 making 400 horsepower.
 
First off 210 isn't hot, and 210 after running sitting still for 20 min ain't bad at all since the viscous fan isn't doing much at those RPM's.
Also keep in mind that those fans are only going to run when stopped and the temp goes up.
Stopped and idling in the rain with the wipers, headlights, tail and markers, all your dash lights and the heater going might be an issue, but then the fans probably won't be running much at all in that kind of weather.
The MAD bypass will help but the engine will be at idle and not producing much charge anyway.

Yep, it's a definite who knows.:D

FYI, it's one of the reasons I run LED's in everything I can but I only have a single 20 amp electric fan.
I also have relays supplying my headlights, so I don't have that drain on the cabin wiring either.
Everything else is really close to what you are thinking you will have, and I don't have ANY low power problems even with everything I listed above.
 
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TrailBeast said:
First off 210 isn't hot, and 210 after running sitting still for 20 min ain't bad at all since the viscous fan isn't doing much at those RPM's.
Also keep in mind that those fans are only going to run when stopped and the temp goes up.
Stopped and idling in the rain with the wipers, headlights, tail and markers, all your dash lights and the heater going might be an issue, but then the fans probably won't be running much at all in that kind of weather.
The MAD bypass will help but the engine will be at idle and not producing much charge anyway.

Yep, it's a definite who knows.:D

FYI, it's one of the reasons I run LED's in everything I can but I only have a single 20 amp electric fan.
I also have relays supplying my headlights, so I don't have that drain on the cabin wiring either.
Everything else is really close to what you are thinking you will have, and I don't have ANY low power problems even with everything I listed above.
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Thanks trailbeast, I was thinking the exact same thing about running all of the accessories at once. If it's dark and raining the wipers, headlights, and tail lights will all be on, but most likely the fan will not even be activated so it really come down to finding out how much the contour fan pulls. I have a 20 amp fuse in my multimeter and ran it inline the battery and cable, with the key in the on position and headlights and running lights on, it was pulling 10 amps. I had just convertEd to the 60 amp 70+ style thinking, " this should be more than enough since I don't have AC, electric fuel pump, crazy sound system, and currently the heater hose lines aren't even connected to the heater so really I'm just running MSD, all of the lights, and a few speakers" well I had heard that electric fans only pull around 10-15 amps, I had no idea the contour fans pulled so much more. I'd like to run these since they are OE and I know I can go to the auto parts store and replace it if ever necessary, and I have only heard great things about them. Hopefully someone running these fans can give a more accurate amp number.
 
68cuder said:
Thanks trailbeast, I was thinking the exact same thing about running all of the accessories at once. If it's dark and raining the wipers, headlights, and tail lights will all be on, but most likely the fan will not even be activated so it really come down to finding out how much the contour fan pulls. I have a 20 amp fuse in my multimeter and ran it inline the battery and cable, with the key in the on position and headlights and running lights on, it was pulling 10 amps. I had just convertEd to the 60 amp 70+ style thinking, " this should be more than enough since I don't have AC, electric fuel pump, crazy sound system, and currently the heater hose lines aren't even connected to the heater so really I'm just running MSD, all of the lights, and a few speakers" well I had heard that electric fans only pull around 10-15 amps, I had no idea the contour fans pulled so much more. I'd like to run these since they are OE and I know I can go to the auto parts store and replace it if ever necessary, and I have only heard great things about them. Hopefully someone running these fans can give a more accurate amp number.
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Everything I find shows about 32 amps with both fans running and an approximate 100 amp spike on startup.
There are fan controllers (Spal I think) that have a slow startup option so that spike is reduced.

One big one is the headlights, since they draw quite a bit of power but if you get them off the cabin and harness wiring with the relay kit you not only have WAY better lights but that load is now off the switches and wiring.
All your cabin wiring and switches only turn the relays on afterwards, so it is sooo much easier on them.
The added available amps from not running through all that wire helps a ton.
 
Nice! I was starting to look into the headlight relays a few weeks ago, but got distracted when some other parts arrived and I was too excited to put them in. Do you have a good write up for the headlight relays? And also sorry for my ignorance with electricity, but what exactly is an amp spike and why would there be one at startup? The fans won't even be on!
 
I run those fans or close to them, with relays on a 26"Champion radiator with a Dakota Digital controller . Mine came out of a 2008 Mercury Cougar.
I also have a GM vacuum pump and MSD 6AL, and three aftermarket guages, allrunning on a 60A alternator.I have not had any issues other than some mild pulsing of the lights at idle rpm, though my headlights at driving speeds are as bright or brighter than most modern stuff.
I did use a headlight relay kit and alternator wire-around, both from member @crackedback, along with a Painless 8 circut auxiliary fuse box to power my accessories and take load off the bulkhead connector. My ammeter is bypassed by siimply moving both wires to one stud, (which can even be done without removing anything from the dash).
I will probably go to a higher amp alternator if this one ever dies, but not a priority until that happens.

Make sure your bulkhead connectors are clean and in good shape, and the mods to take load off them are a good idea.
You can clean connectors by mixing salt into vinegar and soaking them for anywhere from 5 to 30 minutes. Follow that with a dunk in baking soda and water to neutralize the acid. I was prepared to replace all mine, but they cleaned up so nice, I didn't change a single one.
 
68cuder said:
Nice! I was starting to look into the headlight relays a few weeks ago, but got distracted when some other parts arrived and I was too excited to put them in. Do you have a good write up for the headlight relays? And also sorry for my ignorance with electricity, but what exactly is an amp spike and why would there be one at startup? The fans won't even be on!
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Spike meaning when the fans start up, not the motor.:D
Most electric powered devices like electric fans have a much higher load when they first start turning, then as their motor gets up to speed the load lessens.

I do have the info on the relays, but our member @crackedback sells kits just for that and I don't want to step on his toes.:D
 
Knuckleduster, have you tried seeing how many amps your fans pull? But other than that looks like we have a pretty similar situation.

Trailbeast, thank you, didn't know it would be such a high spike, drove the cuda around a nit yesterday and didn't even get above 180 until I let her sit and got to 210 so I'm going to keep an eye on it, I'll let it sit longer and see if it even will go past 210.
 
The alternator doesn't have to match the instantaneous loads. The battery can do that. The alternator's job is to keep the battery charged, so if it isn't running down over a week of driving, you have no problem. Put the battery on a charger every Saturday. If it shows "fully charged" in <30 min, your alternator is keeping up. The electric fans should only run when idling for a long time.

You also need to "calibrate" your dash temperature gage. There should be a "normal position" which indicates where the thermostat is controlling. That will vary +/-10 F, depending on the heat load, since it takes a higher temp to open the T-stat more, but once fully open temp will go up quicker with load. If you know your T-stat's setpoint, that calibrates your gage. It sounds like it might be 180 F and your gage agrees.
 
Thanks Billgrissom, I’m not exactly sure on the thermostat, either 180 or 185 I think, I got it awhile back, but I’ve been driving the cuda the past couple days and it stays at 180-185 driving and then after 30 min or so of driving yesterday, I let it idle for about 10 min and it didn’t get above 190. I think I might be ok. That was also in 70 degree weather though. I’ll get a shroud if it doesn’t do as well in 90+ heat
 
My opinion would be that if you sat in traffic at night in the rain with the fans on and the headlights on that you'd be drawing the battery down with the setup you have, because you won't be getting enough idle amps.

I have the same fans, EFI, 13A fuel pump (aeromotive 340 lph), the regular lights, stereo, etc. My 78A 12SI delco keeps up so long as the wipers are on, but if you do, its drawing power from the battery, (its typically 12.9V at idle with this setup). This alternator charges a ton better at idle than yours does. I would go for a 94A 12SI delco in your case and forget about it forever. Its a really easy swap so long as you have a cut-off wheel and a welder.
 
goldduster318 said:
My opinion would be that if you sat in traffic at night in the rain with the fans on and the headlights on that you'd be drawing the battery down with the setup you have, because you won't be getting enough idle amps.

I have the same fans, EFI, 13A fuel pump (aeromotive 340 lph), the regular lights, stereo, etc. My 78A 12SI delco keeps up so long as the wipers are on, but if you do, its drawing power from the battery, (its typically 12.9V at idle with this setup). This alternator charges a ton better at idle than yours does. I would go for a 94A 12SI delco in your case and forget about it forever. Its a really easy swap so long as you have a cut-off wheel and a welder.
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Is the 78 amp alternator a direct bolt in? and did you need a new regulator?
 
68cuder said:
Is the 78 amp alternator a direct bolt in? and did you need a new regulator?
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Its a GM Delco alternator so the regulator is internal. Its not a direct bolt in but if you can weld and cut, its not so difficult. Flip the stock small bracket, cut one ear off, and weld a cheap $10 mr gasket chevy lower bracket to the original, put a diode in the power wire to the turn on, run one wire for the sensing wire and you should be good since you have larger than stock wiring already.
20151001_182828.jpg

This is on mine.

Just did my friend's 71 Demon this year as well...so better pics:
IMG_20170730_160349.jpg

IMG_20170730_160426.jpg
 
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