Here is how my math works, I hope area still = pie-r-squared
diameter 3/4 = 0.75 in
radius = 0.375 in
0.375 x pie = 1.178 sq in
4 of them = 4.71 sq in
diameter = 2 in
radius = 1 x pie = 3.14 blah blah blah
1 exhaust = 3.14 sq in
diameter = 3 in
radius = 1.5 in
1.5 x pie = 4.71 sq in
Have I screwed up somewhere?
I would get my exhaust AT LEAST in balance with intake. Actually, I'm a pretty strong beleiver in a wide open exhaust and control at the intake so I would be tempted to oversize the exhaust and go to 4 in. I dont know squat about UDS cookers, but I see a bunch on here with only 2 or 3 3/4 inch intakes so I'm assuming 4 might be enough.
Oh yeah, in my house, pie-r-round, cobblers-r-square (maybe rectangular).
PS: stopped by my local muffler shop and picked up a 3 ft chunk of 4 inch for $20 for another build we are starting.
Got a bunch of cooking toys and a custom metal fabrication shop where I spend my time building all sorts of smokers & outdoor cooking gear.