Originally Posted by rxw
Actually not to be anal but a 3' dump plus a separate 2' dump only equals a 3.6' total dump area because it works on surface area...
3’ dump = 1.5 (radius) squared times pi
2’ dump = 1 (radius) squared times pi
3’ area + 2’ area = 10.210 square inches
Divide that by pi then square root it you should get 1.80277564 (radius)
Now double that and you have you total diameter for your exhaust dump-age AREA
flow is going to be a bit different and your method would have less flow loss