Big Block Cooling w/Electric Fans: DON'T DO IT

[SquareRoot]

No sir, I have not followed along with the latest TV series of self proclaimed engineer Masters haha

Ask anyone, they've built the world

Flexies are like some people I know and from experience. They make alot of noise but don't produce much. I got $100 they won't begin to keep a 502 cool let alone a sb. Been there, done that.

 

[Vbb199]

Flexies are like some people I know and from experience. They make alot of noise but don't produce much. I got $100 they won't begin to keep a 502 cool let alone a sb. Been there, done that.

I'm at 208° now with a flex fan and 4 core, running at a borderline lean condition (afr setting) That's pretty impressive for a hot NC summer day with a motor that large IMO

 

[Frankenchevy]

So really, the problem seems to be with the particular shroud design, rather than the electric fans themselves.

Partially what I was wondering..

 

[Turbo4whl]

BUT I will say, I wanna get rid if the flex fan, and totally skip that gimmicky clutch fan ****, and run electric fans.

GM used two types of fans that look very similar. The clutch fan and the thermal fan. The 1971 thermal fan on my rat engine has 300,000 miles on it and still works fine. Yes this big 18" seven blade fan uses horse power when it locks.

With the hood up tuning or checking the trans fluid level at idle, if the fan locks it will blow the hat right off your head. It moves lots of air.

Yes, throw away the flex fan. This is what GM started using to save fuel. They fail. Then the clutch fan, just not the same as the good old thermal fans.

In my opinion, the tiny electrical fans are gimmicky. Lots of things to fail, sensors, relays, fuses, wires, tiny motors and they are made out of plastic.

 

[skysurfer]

I recall somebody, maybe @gmachinz, mounted a big single efan inside the oem shroud. Seemed like the best compromise between the two systems.

 

[bucket]

I recall somebody, maybe @gmachinz, mounted a big single efan inside the oem shroud. Seemed like the best compromise between the two systems.

I think @bluex did it that way too maybe.

 

[Bextreme04]

Yeah, sounds like low quality fans/shroud and maybe sketchy installation. Its hard to get a sufficient installation in an older truck without having the EFI controls. A properly sized radiator and quality single/dual electric fan setup shouldn't even really need to run going up a grade like that, they might need to kick on for a bit getting close to the top, but really if you are running 55-65 mph, you should be getting all the flow you need.

If you bought one of those junky aluminum "high performance" radiator and dual electric fan setups that is really just two fans screwed to an aluminum sheet... that's your problem. The OEM ones will have either fans that cover almost the entire surface, or they will have rubber flaps over the areas not covered by a fan so that air from forward motion is pushed through.

The 454's are notoriously hot blooded, you will also be doing yourself a big favor to have both an in-radiator and external oil and trans cooler. It will greatly help to dissipate heat from the entire drivetrain, especially the engine oil cooler.

Whatever you do, you need a good quality, high efficiency radiator and external coolers. The fans are really just for the extremes of either high load and low speed, or stopped.

What radiator/fan combo were you running? Was it the stock 350 non/AC radiator?

 

[bluex]

I think @bluex did it that way too maybe.

I did an it works FANtastic....

 

[Bextreme04]

I did an it works FANtastic....

I see what you did there

 

[shiftpro]

Obviously you did NOT install the "best" electric fans as you claim.

Do the fans say SPAL on them? You get what you pay for. Of course, anyone can put SPAL fans on a cheesy homemade shroud and peddle it on fleabay.

You just didn't do your homework. Setup properly, electric fans perform as well as mechanical all day long. That's why 99% of new vehicles use them.

And run the extra wide three core rad that the diesel trucks and late '80s BB in the Crew Cab. My 89 parts cabby had a BB and the wider 3 core. My 81 in the avatar pic is factory BB and the regular width 3 core. On a hot day the temp rises a bit, also when towing. That's the best we can expect with the regular width 3 core imo..

 

[bluex]

I see what you did there

I couldn't help myself with that one.


I have a .060 350, mild cam, headers nothing special. It has a vortec 5.7 serpentine setup with a GMP high volume water pump, 180* thermostat, AD244 140A alternator, sanden HT6 upgrade compressor with vintage air.

19" stock radiator (like way stock, this is an older all brass one) with shroud, in the shroud is a 2002 Jeep Grand Cherokee 16" fan. Its ran by either my Sniper at set temps or the trinary switch for the a/c.

If the a/c turns it on it runs about a min a half maybe before it cuts back off. The sniper will turn it on at 204*. Ive seen it hit 207* in the heat of the summer with the a/c on in traffic before the fan can catch up. In probably 5 mins its back down to 197* (where in runs temp wise at 70 mph) an we start over.

I have no worries leaving it to sit idling with the a/c blasting an it 100* out....

 

[75Monza]

I bought a whole GMC diesel burb core support with big rad and all the coolers and had the trans cooler with the electric fan, nice 86 grill and headlight buckets for $100 off craigslist for my K30 soon as I decided to upsize to 454. Only thing I didn't have was the shroud, but got that off my C30 parts tear down...should be cool cruising for me. Until I plow snow with it rolling over the hood, lol.

 

[Catbox]

We went with a set of Flex A Lite fans we found in the junkyard.
Junior did the install and I helped with the wiring.
The set we picked up is a bit smaller than the overall size of our 454 radiator.
But I have to say, they work great at keeping the engine cool.
The needle stays where it has always been with the standard fan.

Of course we don't tax the entire system like what you have mentioned.
Junior runs the truck as his daily go everywhere vehicle.
We don't tow or haul much of anything especially up a nasty grade.

They have been nothing but excellent for us.

 

[Rick Dobbins]

I always figured if I went with e-fans I’d make a shroud to replicate the factory one that stands off the back surface of the rad, fits tight around the edge, but with cutouts for dual fans rather than a large one in the center for the clutch fan. The nice thing about aftermarket efi is being able to trigger one or both fans whenever you want.

Three questions for you:

1. what make and model of fans did you get?

2. what amp and brand alternator?

3. did you notice the engine revved more readily with the e fan setup?

Hi- well the biggest mistake I made is not writing down or keeping receipts for all the stuff I bought, but I can tell you they're all common aftermarket parts and suppliers. Got the fans off Summit Racing. Probably the alt too, as it's rated for 120Amps and factory test sheet it put out 70 amps at idle. The fans were dual, and came with ONE relay (stupid) so I installed two to divide the load and have redundancy. As for the 454 reving, the 7 blade takes 45 HP and I didn't notice a difference. Thought about it too, so I had my ear tuned for that. Metal fan is louder, and it sounds more like a truck. lol

 

[Rick Dobbins]

Flex fans should be outlawed. Have you not watched that episode on Engine Masters?

Love EM's! And yes, ran across that episode after I switched back to a metal fan. In '92 I put a 427 in my '68 Chev 3/4T w/Lance 780 (heavy) and don't remember any O/H issues as I ran up and down 395 in the summer. Never even thought about it.