Round PVC port help

[lilwhteranger]

I'm putting 2 8" sundown sa8.v2 in a custom box I'm making for under the rear bench seat in my 2001 f150. The box is 1.33cu ft. The PVC is 3". I have a 90 degree elbow and a 2 ft section on pipe as well( I know I don't need that much).

So I bought the elbow to use so I can make the port face the same way as the subs(towards the front seats) plus there's more room. I've never messed with round ports yet. So how do I calculate port length with the elbow? Or should I make the port go out the side of the box toward my ext. cab door with only 3.5" of space between the box and the door? I can post a pic later of the box and the port mock later to better understand it better.

[Triticum Agricolam]

One 3" port isn't going to be enough for those subs. They should have 8 - 10 sq. in. of port area each. One 3" port is only 7 sq in.

[Aj11]

have you thought about just running 2 ports? I've seen boxes with 6-8 Ports they look great when done right