Flex Fans

[midnight sun]

I seem to recall that there was an at length discussion some time ago regarding the pro's and con's of using a flex fan.

Anyone care to revisit the subject?  I am considering using one on the 47 coupe.

Thanks

Later

[Dirk35]

The cheap ones, and the plastic ones used on today's modern cars fall apart with age! I had one slpit up on my 91 Explorer at about 175K miles.

[HOTRODSRJ]

The cheap ones and ALUMINUM ones are junk!  The narrow bladed ones do not work.

But, the Derales heavy duty series are great!  Go to http://www.derale.com/flexfans.shtml and check out the 17XXX series only.  These produce more airflow than the GM heavy duty big block fans and will not take the hp the others do. Also, relatively quite.  

I use the 17" on my wife's 69 Camaro, 400+hp, air, Hotlanta traffic...and always runs on the thermostat cycling point, regardless of temp, traffic or air!

[Sean]

I don't know if its considered a Flex Fan or not, but I used one of Flex-a-Lite's "Race" fans when I put the last motor in my Truck. After about two weeks of listening to the noisy thing, it got pulled off and replacced with an electric fan.

[rick 36dodge]

I have a stock Chevy 7 blade fan on my 36 Dodge with a 350 Chevy. Works great and it is quiet. The thing I like about it is it pulls a lot of air at idle whitch works great with A/C. I don't know how much HP it pulls ,but it flattens out just above idle. I got it off of a late 70s or 80s Chevy RWD station wagon.
I also put one on my 79 Corvette and it worked better than the stock clutch fan.
Rick Harris

[C9]

The Derale's are a nice fan.
Their blades are centered on the hub when viewed from the side.

Not a problem for most, but if you want a little more room between fan and radiator you can gain an inch to inch and a half by going to a Hayden.

Hayden fan's - the ones I've seen - have their blades set back on the hub.

I run a 6 blade (and did run a five blade) Hayden in my 32.
Both fans just barely clear the V-Belt - maybe a 1/4" clearance at most.
That's not a problem cuz once the engine is running the blades flatten out a bit - even at idle - and you gain a little bit of clearance.
The Haydens are very good about not pulling forward when the engine is spun up.
The 32 has maybe an inch clearance between fan and the flush aluminum allen plugs in the radiator oil cooling tank.

The 17" diameter fan is the largest you can run on the 455 Buick in my 32.
The engine in that car is set 1" to the right.
Thought I needed the extra clearance, but didn't.

The 31 - shown in the pic below - runs a 15" six blade Hayden.
The 455 Buick engine in that car sits in the middle.

Far as cooling goes, the 32 idles through summer traffic (100 degrees F +) with no problems.
I expect the 31 to do the same.

[Dirk35]

Looks lke you got really GOOD air-flow to the fan on the 31 there C-9! HeHe!

The garage int he background.....Bet it was "fun" moving all that stuff!

[C9]

Looks lke you got really GOOD air-flow to the fan on the 31 there C-9!

I gives it that 'airscrew' effect . . . ya know?