Flex fan

[SoFloG]

It looks like nobody has yet given you a clear, direct answer to your question. The short answer is yes, this has been measured... and an electric fan typically draws 1 HP or less compared to the same engine with the same alternator spinning but not powering the fan. Here are two pages from a relevant Car Craft dyno test answering this exact question:

As you can see, going from no alternator to an unloaded alternator cost 1.0 horsepower, and then powering the electric fan only required an additional 0.6 horsepower in drag. Alternators are extremely efficient at making electricity.

Thank you man! Somebody gets it!

 

[olds307 and 403]

I actually had a temp switch fail, twice. It's been good so far. I teed a female spade into the relay trigger, and have a male screwed to the firewall. That way, I can run the fans manually without the thermo switch.

I have used the rad probe style adjustable, adjusted itself constantly. I have had multiple relays fail and screw in switches in different brands as well. I currently have the adjustable Flexalite controller. I have had two relays fail in it. I will continue to use it as all rest fail from my experience. I will just buy two relay boards at a time and leave it wired for a complete manual override independent of the controller via a toggle switch. I can't have Dr Olds Mileage Machine overheating now can I.

 

[DJHull]

Replacing the clutching fan with a dual electric fan helped a lot. The extra 50 or so HP needed to run the fan made the motor run even hotter.
We added a 6" deep core support air dam to increase flow through the radiator and blocked off the upper grill to reduce front end lift.
Front end lift is a major driver of very high speed overheating on a G-body as it pressurizes the back side of the radiator, reducing flow through the radiator. The intercooled Turbos are the worst for this, because the actually pipe air to the wrong side of the radiator.

You know your stuff. I see you race and have all kind of mods I do not have. I just have a 455 that has 432hp/503 ft lbs torque. I am running a 4 speed Muncie from Mid West Muncie and a posi loc Ford 9" Currie with 3.50 gears. Will I gain anything going with an electric fan over a mechanical?

 

[UNGN]

You know your stuff. I see you race and have all kind of mods I do not have. I just have a 455 that has 432hp/503 ft lbs torque. I am running a 4 speed Muncie from Mid West Muncie and a posi loc Ford 9" Currie with 3.50 gears. Will I gain anything going with an electric fan over a mechanical?

Yes, especially with a manual transmission.

I can't think of one manual transmission performance car built in the last 30 years has a mechanical fan.

Dual fans are $35 at the junkyard.

 

[UNGN]

Thank you man! Somebody gets it!

That article is 17 years old so its a little dated and a little misleading. They don't test the fans behind a hot radiator which will "lock up" a thermal clutching fan and Rob serious HP. 487 HP out of a Summit Thermal fan my *ss. Point a heat gun at the fan and re-run the test. Marlon Davis is a super sharp guy, but don't know what he was thinking, here.

Electric fans were $250 back then and not plentiful in the junkyard. Now they are $100 new and $35 in the junkyard and most junkyards have 25 - 50 good ones.

 

[UNGN]

I have used the rad probe style adjustable, adjusted itself constantly. I have had multiple relays fail and screw in switches in different brands as well. I currently have the adjustable Flexalite controller. I have had two relays fail in it. I will continue to use it as all rest fail from my experience. I will just buy two relay boards at a time and leave it wired for a complete manual override independent of the controller via a toggle switch. I can't have Dr Olds Mileage Machine overheating now can I.

Its a little more work, but If I install a controller, unless its some kind of PWM deal, I have it "control" cheap, replaceable relays. I also try to soft start the fans on lower voltage, then switch them to high speed only after they are moving. The greatly reduces the amp draw, contact sparking, and the load on the system.

Dual Fans may draw only 15 amps running, but at start up they can draw 50+ amps as they get up to speed. Soft starting 2 fans in series, then switching them to parallel reduces the amp spikes.

 

[vanrah]

Greetings Guys; Old info from yesteryear. I had an all aluminum flex fan including the rivets on my ole Suburban as the original owner had removed the OE clutch fan. One very cold winter morning the carb was up on fast idle & I kicked the gas pedal. The engine went form about 1500 to 2000 RPM & the flex fan Exploded taking the radiator with it, junk! Also damaged the glass hood. Then as the years passed (before electric's) many magazines ran tests on various fans. I've been a fan of the Flex-a-lite #5555 clutch & they seem to last about 15-20 years give or take. And rob the least HP the mechanicals. I'm on my second one about 5 years now. I have to agree with UNGN that now days electric are the answer but for many of us still running old electrical systems with V belts, the costs are more than just a junk yard electric fan (s) setup. Not to mention dependability. No flex fans, Ole' Bob

 

[UNGN]

The clutch in my Yukon XL broke and took the fan with it. I was 700 miles from home on vacation and spend $100+ replacing the the POS clutching fan, and when I got home, replaced it with an LS1 fan setup that was less than the Clutch and Fan. Anybody need a 6.0L Fan and Clutch with only 700 miles on it?

 

[DJHull]

Yes, especially with a manual transmission.

I can't think of one manual transmission performance car built in the last 30 years has a mechanical fan.

Dual fans are $35 at the junkyard.

Excellent info! Thank you!!

 

[DJHull]

Thank you man! Somebody gets it!

Thank you man! Somebody gets it!

Excellent info thank you. My mechanic is wishy washy on which way to go.