flex fans

[machoneman]

On the slipping v-belts, one should consider the pulleys, the material they are made or and how slick the grooves may be.

Odd, but over the years I never had on GM, Ford or Chrysler cars any belt slipping issues unless P/S fluid or leaking antifreeze got on those steel pulleys. But, on my first run on the newly built 351W in the Mach 1, I did hear slippage at quick throttle hits. The new and all-aluminum March pulleys had a too slick finish to the v-belt grooves! Some sandpaper roughed them up and today and ever since, no more slippage. 

[Falcon67]

I use 6 rib pulleys on the Falcon and haven't had any slippage issues.  Having said that, the dragster uses a belt to drive the 50A alternator and one to drive the vacuum pump.  Neither require much load to turn, AFAIK. 

[jayb]

I think 30 HP is certainly possible with a good V-belt....

And yet on this forum, in the very near past, there is a thread asking for help in stopping V-belt slip and screeching when using a 3G alternator, which at the high end are rated at 130amps. 

The slipping is on startup, Gerry, not steady state.  Certainly you must understand that accelerating a mass from zero speed is a different situation.

[GerryP]

...Certainly you must understand that accelerating a mass from zero speed is a different situation.

No, no, I had no idea.  I've never been bonked in the head by an apple, so physics is unknown to me.

[dcm0123]

The last flex fan I had was on a 1976 full size Ford.  A piece of the Ford OEM fan flew off when I rev'd the engine standing next to it.

Plastic and metal flex fans will both fatigue over time which can create a safety hazard. I use rigid fans, thermal clutch and electric. Preference is a large diameter, high CFM, electric with a proper shroud to pull air through the entire radiator. You loose a lot of cooling capacity if you install a round fan on a square radiator without the proper shroud.
 
If you go electric, install a heavy duty relay, not the one in a plastic shell about 1" in size with push on terminals. The plugs ans wires these come with are only suitable for 20 amps.

Installed a conventional thermal clutch on a 69 Mustang with a 390 to keep it original. Was not able to find a heavy duty clutch which fit because the space for the clutch is very limited.

[fryedaddy]

i was overheating when i ran hard or at highway speeds.i would slow down and it would cool off.i changed fans to see if it would help.turned out my bottom rad hose was sucking shut when i revved the motor over 2500 rpm.went to one of those ribbed hoses with a wire inside.ok after that