How do you add port?

[Flipx99 5,000+ posts]

I have built a few boxes, but they have all been by step-by-step programs. I am looking into putting some 8s on my rear deck. The L78s require .75cf sealed and 1 ct ported.

I can fit 4 of the sealed with box dimensions of 37.5 * 10 * 15.25 = 3 cf (internal)

--not 3 but close as I can using easiest to cut dimensions

or

I can fit 3 ported, with box dimension of 37.5 * 10 * 15.25 = 3 cf (internal), but how do I add the port? I have seen slotted box where the port looks more or less like an addition to the box. How do I calculate that part?

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[Flipx99 5,000+ posts]

Why is there a difference in power handling between sealed and ported?

 

[THUNDERBIRD 10+ year member]

http://www.accelerator-pedal.com/ported-box.asp here is a program were u can punch in ur numbers. its what i use see if it works