[my427cobra]

OK. I am now beginning to understand why the Stelling & Hellings air cleaner flow is so questionable.

First, it turns out I was using incorrect info as I calculated the effective area of the S&H filters.

The perforated steel filter sides have only a 28% effective ("open) area, not the51% I had used in my calculation.

And the Speedway air cleaner tops I was using have only a 38% effective ("open") area, not the 51% I had used in my calculations.

Second, the green foam filter is probably a 65 t0 75 PPI (Pores Per Inch) foam which is a "fine" filter foam. Great for particle filtering but not so great for air flow.

So back to the drawing board.

Cheers
Greg