7 blade 17” fixed fan vs 6 blade 18” clutch fan

Fixed fan - 100% fan speed to wp speed.

Clutch fan - 60 to 80% fan speed to wp speed.


Fixed fan at road speeds need almost no HP to turn.

Same with thermal fans


Fixed fan with same number of blades as thermal fan with same pitch and diameter will move more air.

Benefit of thermal fan is you can have a steeper pitch to move more air and it can be quieter at various conditions.


As for squeal...
Tighten the belt/s
Be sure you have the correct belts
Be sure the pulleys are in good shape.