help with aero port

[austin letner]

Hello all and thanks for the help.
So im preparing to build a new box it is 5 cu ft (5.26 technically) tuned to 34hz with two 12s in it. I am having trouble finding my port length im using straight 6" pvc pipe, on one program it says i need 6.65" and another it says i need 8.. So any help would be great! also says port area is only 28.26?

 

[Max Warasila]

Build a prototype, start at 10" or so and chop off excess until the tuning is about right. You can check tuning by finding your impedance minima.