[Butcher]

Generally torque isn't the issue so much as fan size (both diameter and thickness) in determining the maximum backpressure. You can have loads of torque but given enough backpressure the fan will just cavitate.
If you are having problems shifting the air I'd suggest a bigger fan - 60mm is tiny, you'll get much better results with something like a 120mm or bigger (I use a 172x55mm on my radiator and it's great).