belt driven dust collector

[Highdesertww]

When I bought a motorless blower from Grainger years ago, the maker gave the option of direct drive and belt drive, with the same 1 hp motor.
When the belt driven speed is at about the recommended 4500 rpm, the suction or cfm is increased by about 40%.

I believe many motors for DCs are under-used. I have a 3 hp DC (Hercules) with a motor 230V 18 amps running a fan the same size as a 2 hp DC. I believe this motor is under-used. I plan to turn it into belt driven and run the fan at 4300 to 4500 rpm. 

Is turning a DC to belt driven very rare attempt?

BTW, my DC system is two stage with a large drop box so large chip hitting the fan is very unlikely.

Also, the fan from Grainger is aluminum alloy and the fan for the Hercules is steel, both radial fin of course.

[daddo]

Too many factors to consider to give you an answer.

( "I have a 3 hp DC (Hercules) with a motor 230V 18 amps running a fan the same size as a 2 hp DC")
  How do you know the two fans have the same pitch and design? Is the fan rated for a higher RPM?

The pulleys with belts, the additional speed/static and added bearings will all add HP requirements.

If the motor is already near it's rated amps as it is, then no- adding the additional loads won't work.

I tend to be satisfied when something is working fine the way it is. I've screwed up a few things trying to make it better than it needed to be. But I also say- go for it with reasonable research and calculations- that's the way to learn.

[TDKPE]

From the Fan Laws, air delivery increases proportionately with increase in speed, sound output increases as the square of the speed change, and input power increases as the cube of the speed change. An increase in in flow resistance will mitigate that power increase, but the point is that power input goes up steeply with speed, so do be aware of that.

For what it would cost in shaft, bearings, sheaves, and belt, it might be cheaper to get a larger blower wheel. Maybe an airfoil wheel, which is more efficient (more air per hp), but they have their own problems. Or extend the vanes a little (doesn't take much) on the existing wheel.