What overtime? The fans only run when stopped at a light, in stop and go traffic, idling at the drive-thru, or running extra to help your AC work. The rest of the time they are off. What do you care about HP loss in any of those scenarios?

Also, 14V, 28 Amps (dual Spal fans), that's 392 Watts. Even if your alternator were 50% efficient, 800 W is barely ​​​​​1 hp! Say it with me: One Horsepower! And only when it is most needed, when the belt-driven fan would be least capable of doing anything.

What if the electric fan naysayers had actual data to back their claims?

 

Just sayin.' Just asking.
Does not matter to me.
I will stick with the old clutch style and old ALT.

Good grief. Don't bark at me man. Just making conversation.

 

I'm glad you found a solution that works for your car! Hopefully the OP does, too.

 

I have a Lincoln Mark VIII fan but I do NOT have amp numbers.
I do know that if I'm idling (about 650-700 rpm) and battery voltage is about 13.8 to 14.0, and all loads are running (a/c efi, efi pump, radio, a/c fan, etc), and the Mark VIII kicks on, THEN my voltage will dip to about 12.5 VDC before my 140 amp CS-144 slowly brings it back up.
One of my back-burner projects is to wire in a 160 amp DR44G..... but since it's maintaining I haven't done jack (and I'm sooooooo lazy).

 

The alternator only robs the hp WHILE the load is placed on it via the fans running. and since the fans only run while the car is doing stop and go or sitting in traffic idling its much less of a concern. EDIT * I really need to finish reading before replying.. and I really miss the DELETE option.

 

lol we tend to get a bit testy when constantly defending our choices but I thought it was a good question to ask as it helps explain things for others to stumble on and read and that how a lot of us learn.

I'm used to the defensive stance though as I find myself defending choices like the solar panels on my roof to folks that are drastically misinformed about what they think they know.. Some folks have flat out accused me of being a liar when I tell them my experience and it doesnt line up with what they want to be true. We all do it though in some way or another as we become older and resistant to change or develop a bias against things.. I had a bias against the TBI systems based on a lot of what ive read over the years and it took a bit for me to even consider purchasing one and giving up the carb.
BTW my dual fans do work fine with a high output 10si alternator so converting to a differnt style is not needed but something larger than the 40 or 62 amp would be advised. I just purchased a 140amp 12si ($65) to better power the EFI along with everything myself...

 

I almost hate to point this out but engine masters did an episode where they showed how many HP the alternators and other accessories each consumed and they were surprised at how many hp the alternator consumed when under a load. I dont think it was anything crazy but it was more than 1 hp.. I dont remember the specifics of the amp load was though. I dont know about others but ive felt and heard the load on the engine from the alternator when a large electrical load is put on it and it can be significant.

Years ago in another life I installed car audio and I had a stereo system in my jeep that would stall the engine right out at a stop light if I turned it up too loud.. and that was with a yellow top deep cycle optima battery and a 1 farad cap in fairness it was about 7000w of stereo power. Dumb... I know.

And the OPs fans draw 180watts together so I think we can agree they are at least part of the issue here.

 

Well, that 7000 W is at least 10 hp, likely more depending on the alternator's efficiency.

I found the Engine Masters episode, "If Accessories Could Kill". It's a Facebook link, so I won't post it here, but you might find a link that works for you.

I could not figure out where they measured the load on the alternator. But if that alternator is drawing 150 Amps, (for example, they had connected it to the low battery that had been running their dyno tests all afternoon), then that's 2100 W, and at 50-60% efficiency, thats the 5-6 hp they claimed in the video. So that tracks.

Where are you getting 180 amps for the OP's fans? A Spal fan is about 12 Amps.

 

Sorry meant to say 180watts.. I'll correct.
The photo of fan shows a sticker that says 90w on each fan.

 

That makes more sense.

I'll reserve judgement until the OP comes back and clarifies if the issue is at speed or idle.

If you want to dive deeper than Alternator, 55% efficient, here you go:
https://www.delcoremy.com/documents/...ite-paper.aspx

 

Id venture to guess its overheating at both speed and idle since I can see a huge gap and the top almost like the rad doesnt even fully fit the mount and theres no seal. I dont think the shroud is the issue here I think sealing up the rad and better flowing fans would do the trick as long as the rad can support enough cooling.
My uncles 76 had similiar cheap fans on it when he bought it and no seal and he had nothing but issues. He ended up replacing the rad and sourcing a oem shroud and using a locked mechanical fan (likely costing him close to 30hp) but hes more focused with making it closer to original than anything so it works for him and hes not mechanically inclined so the simpler the solution the better.

 

One thing the Engine Masters Dyno testing doesn't take into account is at higher speed the fan load is reduced from the windmill effect 🤔

 

This is a valid point to a degree I thought about this as well. But the fact remains that even at speed the fan would still be spinning so much faster than the wind that it would still be seeing resistance and be pushing air so I and not sure it would have all that much effect especially when those want the edge the most at the strip.

For me though since I dont race its more beneficial to have that extra hp when taking off from stop sign to stop sign or when I enjoy being thrown back in the seat when hitting that pedal on an open road. Its just another one of those every little thing helps kind of things. I also port matched my heads and intake which many will argue isnt worth the time but time doesnt cost me anything and I enjoy doing the mods.

 

I'm late for the party here, but the first thing I see is that the flaps on his shroud are hanging in the open position while the car is obviously not moving. The fans are not pulling air through the radiator but through the flap openings. This would lead me to believe his problem is at idle or low speeds, not at highway speed.

 

For reference the flaps on my spal clone setup also hang open like that while sitting until the fans kick on and suck them in closed. This is due to the angle of the rad in our cars. I did wonder if that rubber was thin and pliable enough for that though. It does appear the engie and fans are off in the photos so..

It may not be easy to see but there really is an unusually large open gap between the top of the rad support and the top of the rad.(I see like 4-5 inch tall opening as the shroud bracket appears to be filling some of the space) like some sort of smaller universal radiator was installed here that gap allow much of the air to just bypass the rad.

 

Well, I'm not struggling for seven horsepower. What concerns me more is the possibility of a blown fuse or relay failing in the middle of nowhere or the alternator having an issue do to load, because well the just don't make stuff so good anymore.
I'll keep things as analog as I can. Enjoy your electrical do dads I'm for keep it simple stupid because maybe I'm just stupid.

 

Again implied bias aside... Its likely not 7 hp if its been shown to rob as much as 14hp with a smaller 6 blade clutch fan. As far as blowing fuses for some strange reason or a higher amp alternator not being reliable to support a fan? Well thats more about proper installation. And I would argue if an alternator cant handle an intermittent 20-30amp load because of build quality it can leave to stranded just as easily regardless. If a person has a stock 62 amp alternator and they no longer have functioning AC they already have the ability to run a Lincoln fan setup vs the 40 amp alternator on non AC models.
I put a bypass switch on one of my fans to enable me to turn it on manually if ever my temp sensing fan control fails but the key point here is my 84 corvette had electric dual fans from the factory (with a stock 80 amp 12si alternator, AC, Bose sound system, digital dash, fog lights and TBI so the common suggestion about 140amp alternators being needed is unfounded IMO)... They are still going today as I just saw my old 84 on facebook for sale with 168,000 miles still sporting the factory setup. I would argue this isnt some sort of gimmicky "Do dad" anymore than your hood scoop is...

No one is calling anyone stupid. If you prefer your old school original fans thats your choice and its fine.
If anything its the opposite as those of us with the electric fan are the ones being criticized here for our own choices in every electric fan thread. You just did it yourself as you insulted us by calling them "electrical do dads" I'm just trying to share actual Data about the differences in the two systems so people are better informed about whats real and whats exaggerated or opinion

Some folks choose to use lighter lithium batteries in these cars now and sure they have their advantages.. But on that subject I choose to stick to my Lead acid battery because its a non issue or concern for me. Its not always a one options "BEST" for everyone situation. Yes ive pointed out my opinion and even caught myself defending my choice like its the best.. But ive never actually tried a lithium battery as a starter battery replacement so..

 

It appears that the fans are positioned in the wrong locations. Let me try to explain, the inlet to the radiator( top hose) is the hottest part of the radiator with the most coolant flow, yet there is no fan there. I think the cooling will be increased with a fan placed in that section. Also the fan on the passenger side should be placed near the outlet of the radiator. And then there is the problem with the shroud not covering the entire finned area of the radiator. There is probably something to be gained there. And finally, like others have posted; radiator seals to direct the air stream thru the radiator. The air will take the least path of resistance, meaning it will find gaps in the frontal area of the car as opposed to being directed thru the radiator. The radiator has a higher resistance to air flow than a gap in the frontal area so the air will seek out the gaps because they have less resistance than the radiator. These gaps need to be sealed so all the air is directed thru the radiator. The flaps on the shroud need to be addressed also. With the fans running, they should seal the shroud. When the airflow thru the radiator exceeds the fans' air-flow, they should open. If all that doesn't work, you may have to increase airflow with stronger fans or put the factory setup (clutch fan) back on.

 

As long as theres a fan over both the upper and lower core tubes to cool the fluid as it passes across it shouldnt matter from how I understand it but I could be wrong especially since theres a shroud to pull from the whole surface area and not just where the fan is located..... Also this is setup the same way the dewitts shroud works and I think other use it without this issue.

Either way we need more info. that pic shows a short unknown rad and we dont even know how well the shroud is aligned with the actual rad. wealso dont know if the lower hose has the spring in it to prevent collapse under vac pressure

 

The fan placement is the way it is because the left side A arm interferes with the fan housing. It just doesn't fit the other way.

Above, I've posted lots of info and my thoughts on the suggestions here.