Made a FOD from a tea strainer, $1.00 at "Dollar General", fitted another make turbine perfectly, 3.75" O.D. . I also worried about the reduction in air due to the mesh, so decided to measure.
The mesh wire is .006, the mesh centers are .032, calculating shows a 67% air to mesh ratio.
The total available surface area of the mesh is 16 Sq in, take away the area of the starter and you are left with approx 15 sq in.
The available air entry is 15 x .67 =10 sq in . The area of the the compressor is approx 3.14 sq in.
So is the 3:1 ratio sufficient?
Thanks
Bob