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Flex fans

old guys rule

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I have never heard anything good about Flex fans. What is the general consensus out there? I'm strapped for room and I'm not sure the electric fan I have now 16 inch will do the job Cooling a mild Street 440.
 
From the tests I've seen they rob a lot of horsepower and will kill you if they break while you're working on a running engine. Also they look ****.

Apart from that, they're great.
 
I haven't heard much about them that is good....I won't ever use one.

Watch one grow when the revs are applied.....not keen to stick around if those blades let go.
 
I've had a high-dollar one come apart at speed before. Shrapnel everywhere and carnage,
including part of one blade spearing through the steel hood of the car.
how-about-no-bear (2017_10_11 10_04_54 UTC).jpg
 
Plus you sound like a school bus when you are getting into the higher rpms. Flex fans sound like **** when wound up.
 
Just don't like the flex fan's. The blades are not as big as the original one and really don't think they move the air at low rpm's like a seven blade fan. I got the original one and put it on my car and it cool's the engine fine at idle. On the electrical fan may be you can put one in the front of the rad. If their is room. Seen that done also. Push in stead of pull. Yep go along with what others have stated about flex fan's.
 
Hard to improve on the factory fan. Sometimes there just isnt a better mousetrap.

IMO.....the reason most people use them is: They are inexpensive (cheap)....that leaves a few $$$ left over to fund the purchase of a few brown bottles. Plus the flex fans do not cool worth a s**t and no supplier can produce documentation about their performance....CFMs moved at various RPMs....
BOB RENTON
 
I hear about "I had one blow up" or "I heard of a guy who had one come apart" so often when it comes to flex fans. I would think w "so many" bad fans, there would be "lots" of photographic evidence and lawsuits. I personally won't use them but not for those reasons. However, Flax a lite does make a large blade fan, looking similar to stock that is designed to be run on a spacer, not clutch. And rated to 7k rpm. Mopars came without a fan clutch at one time. The fans without a clutch put more draw on the engine and make much more noise, but they work. I run a serpentine setup w no room for clutch. Reverse rotation water pump, using a white 11 blade 19" fan from Chevy 496" truck. It's very noisy, buy holds up just fine n cools great. Try a factory fan w spacer.
 
Here are Flex a lites factory style 18" fans.
Screenshot_20210917-073736_Chrome.jpg
 
Here are Flex a lites factory style 18" fans.View attachment 1167579
VERY NICE PICTURES......BUT, "pulls more air at idle" means nothing.....how much air is "more air"? Quantify with a CFM number and at what operating RPM. Regarding the race fan application, what components are "not needed for a race application"? AND WHAT IS THE MAXIMUM RPM that is allowed b4 self destruction.
The whole point of a fan clutch is to limit the fan's RPM to limit the HP consumed at "race speeds" and have more HP available to propel the car. Refer to an excerpted fan law explanation below.

Fan Law 1 tells us that the change in air flow rate of a fan is proportional to the change in speed of the propeller. If the propeller speed is increased by 10%, the air flow rate will also increase by 10%.
Fan Law 2 tells us that the change in total static pressure of the ventilation system will increase by the square of the change in propeller speed of the fan.If the propeller speed is increased by 10%, the total static pressure will increase 21%.
Fan Law 3 tells us that the change in horsepower required by the fan to turn the propeller will increase by the cube of the change in propeller speed of the fan. If the propeller speed is increased by 10%, the horsepower required to turn the propeller will increase 33.1%.
Sort of self explanatory.....
Moral of the story......ASK FOR SPECIFICS B4 YOU BUY......
BOB RENTON
 
I'm using a one piece plastic flex fan (not the aluminum kind with riveted on fins, the ones that come apart). Engine masters has proved that it is very horsepower inefficient. They didn't test how well it cooled, or how much air it moved.
Mine is on a 500hp bracket car, and it keeps my car cool. It might be costing me a tenth in time, maybe 20hp. I could probably get the tenth back with a clutch fan or electric, but how important is a tenth on a bracket car?
It keeps my car cool. I thought that was a fans job?
 
VERY NICE PICTURES......BUT, "pulls more air at idle" means nothing.....how much air is "more air"? Quantify with a CFM number and at what operating RPM. Regarding the race fan application, what components are "not needed for a race application"? AND WHAT IS THE MAXIMUM RPM that is allowed b4 self destruction.
The whole point of a fan clutch is to limit the fan's RPM to limit the HP consumed at "race speeds" and have more HP available to propel the car. Refer to an excerpted fan law explanation below.

Fan Law 1 tells us that the change in air flow rate of a fan is proportional to the change in speed of the propeller. If the propeller speed is increased by 10%, the air flow rate will also increase by 10%.
Fan Law 2 tells us that the change in total static pressure of the ventilation system will increase by the square of the change in propeller speed of the fan.If the propeller speed is increased by 10%, the total static pressure will increase 21%.
Fan Law 3 tells us that the change in horsepower required by the fan to turn the propeller will increase by the cube of the change in propeller speed of the fan. If the propeller speed is increased by 10%, the horsepower required to turn the propeller will increase 33.1%.
Sort of self explanatory.....
Moral of the story......ASK FOR SPECIFICS B4 YOU BUY......
BOB RENTON
I appreciate that you want to show your expertise. There is "No" cfm per rpm for the factory fans either. The OP asked for some info on Flex fans. I appreciate that you are bored.
 
I've used stainless flex fans on my drag car, worked fine. I ran my motor to 7,000 RPM all the time. I did switch to a plastic fan with a Moroso electric drive with that, worked really great.
 
I appreciate that you want to show your expertise. There is "No" cfm per rpm for the factory fans either. The OP asked for some info on Flex fans. I appreciate that you are bored.
Bored??? Absolutely not. I believe the OP asked if flex fans were any good.....IMO....short answer....NO. With regard to the use of fans in general, the presented information is to help make an intelligent decision....take it or leave it....its up to you. But without accurate information its impossible, or nearly so, to make a worthwhile decision....about fans or just about anything else.
BOB RENTON
 
I thought the whole point of flex fans was, the blades "flex" and flatten at higher RPM thus eliminating drag and freeing up a little power....but you guys are saying they cost power? I've never used one, just curious..
 
I run a fixed blade 18" 7 blade Chrysler fan, It makes noise and I am sure draws some horse power.
It will hold a dollar bill to the grille front at a 700 rpm idle, I do use a fan shroud and have good seals from hood to cowl and hood to radiator support. It is for sure a old style system but it does work.
The flex fans advertise the fact that once they are at higher rpm the blades flatten out to use less horse power , that and light weight are their claim to fame. My old 440 seems to have enough power for me I like the fact that the chrysler fans keep moving lots of air at any rpm.
 
I thought the whole point of flex fans was, the blades "flex" and flatten at higher RPM thus eliminating drag and freeing up a little power....but you guys are saying they cost power? I've never used one, just curious..
Oh yeah, they eat power. Engine masters did a fan test to find out how much power they use. They tested the plastic "flex" fan I use, with a bunch of fan pitch, and it ate 25 hp. The fixed standard blade was somewhere around ten worse yet. Best was a factory clutch fan, ate somewhere around 10-15 hp.
Some questioned their test methods, but I think they were close.
My fan probably eats that much, but it keeps my engine cool. THAT is its job.
An electric or two could probably save a few hp, but I would rather not have to deal with them on this car.
 
Oh yeah, they eat power. Engine masters did a fan test to find out how much power they use. They tested the plastic "flex" fan I use, with a bunch of fan pitch, and it ate 25 hp. The fixed standard blade was somewhere around ten worse yet. Best was a factory clutch fan, ate somewhere around 10-15 hp.
Some questioned their test methods, but I think they were close.
My fan probably eats that much, but it keeps my engine cool. THAT is its job.
An electric or two could probably save a few hp, but I would rather not have to deal with them on this car.
Okeedokee!
 
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