Port Location Question

Where is the best location for the port? How far from the side walls does it need to be and where should the end of the port be in relation to the sub magnet?
I will have images up soon of my ideas for my design, but I am not sure how accurate the dimensions are for where the port is located...any help/advice would be great!

okay...so if i have a 3" port 12" long, the depth of the box needs to be 15" so the 12" has 3" between the end and the opposite wall?

and then i need a total of 9" between the edge of the sub and the exterior wall where the port will be in the center of.

would it work putting the port on a side wall or does that lose its effect?

1.  Yes, if the tube were going straight toward the back.  No, because you can put a bend in the port tube.  As Francious said, the port should vent to the same side as the woofer....but the other end of the port can be just about anywhere within the enclosure.

2.  No, the rule for port tube placement is first...use what you have to work with.  And keep the open end away from any object at least the diameter of the port.  Look at the space you have to deal with, bend the port if you need to, keep the port tube as far from any outside wall and as far from the woofer that you can.

3.  No, and yes.  But in all reality, take the placement of the enclosure into consideration.  The criteria used for a sub in your livingroom is different than that of a box in the trunk.  If your enclosure is in the trunk, it really doesn't matter what side the port vents to.  But if the box is in a place that is in your direct line of listening, it is better to vent to the sub side.  But I see premade enclosures for both car and home with vents to the back, and sub boxes for trucks with vents to the top.  I  have a sub enclosure in my home audio system that ports to the rear, and it works just fine.

Most enclosure builders, I would venture, situate the port wherever it fits best.