When you 1st posted it I tried for a few minutes to figure where 0.0009875 comes from, part of of it must convert cubic inch to cubic feet, per revolution (every other stroke) 1 cubic in = .0005787 cubic feet / 2, so 360 x 6000 x .0005787/ 8 /2 = 78 actual cfm vs the 266 cfm of need head flow. That's far as I got, problem with head flow is the depends on a depression, there's not a direct translation between the two. Why the carb formula doesn't work unless the goal is to have 1.5 hg at WOT.