Changing a pulley to get more air or water? Check the new flow, pressure and power first: power rises with the cube of speed.
Power rises with the cube of speed: 10 % more speed needs about 33 % more power; 20 % more speed needs about 73 % more. Flow rises in proportion to speed and pressure with its square.
They apply to centrifugal fans and pumps working on the same system. They do not apply to positive-displacement pumps or compressors.