Center port design

[Tat2Art1st]

Box External Dimensions Width × Height × Depth	34.00" × 13.00" × 22.12"
Material Thickness	0.75"
Net Internal Volume	3.75 ft3
Tuning Frequency	35 Hz
Port Area	52 inch2
Port Inlet Width × Height	4.52" × 11.50"
Port Length	21.69"

 This is the box design i came up with for 2 12" Skar audio subs. These calculations are for front facing subs with front facing side port. But I want the subs pointing up with a center port. how do i figure out the port length cuts for center port. I'm assuming i cant just move the port to center and use the same length or can I?

[Joe X]

The port in the middle (shared port) adds displacement because there are two non common walls instead of one of the side port design. Besides you don't say what skar subs or power or vehicle you are running which are also important in deciding a design.

[Tat2Art1st]

gotcha a its in a 2003 bmw 325i (2)Skar SVR 12" subs, Skar audio RP2000.1 

[Joe X]

So here is a suggestion, power: to sub(s) rated, amp subsonic filter to 28Hz, minimum port clearance 4 1/2", figure is just an assembly guide:

 

NOTE: If building outside you need to build a cardboard dummy box to test fit in it's way inside.

 

NOTE: for increased performance subs and port should be firing rearwards.

 

 

 

 

[Joe X]

I came up with a shared port design which is approximately what you intended to do in size and performance. Subs up in trunk cars is not recommended due to heavy trunk lid rattling, if you choose to do the subs up just do the cutouts in the top wall instead.

 

The other thing to comment is that many european vehicles have almost air tight trunks, that would result in reduced performance, if removing your rear seats results in you being able to see the trunk, you are ok but if you see just metal, it can be a problem.