As you ask BlenderPilot
A starting point for you to consider follows and all figures are in ISA conditions.
The total weight of air going through a PT6A-60A (King Air KA300/B300) at Take-Off power is around 8.96 lb/sec. Air weighs about 2.87 lbs per cubic metre, therefore around 3.12 cubic metres or 110.18 cubic feet per second.
The PT6A-60A embodies a 4-stage axial, single stage centrifugal compressor. The less powerful PT6T-3D/PT6B-36A/B Turboshaft engines have one less axial stage so I would hazard a guess that volumetric flow is probably around 70 to 80% of the 60A.
Saturday afternoon in the sun, how sad am I????????????