Help design ported box

I've built many sealed boxes over the years but never a ported one. I want to build a ported box for 2 Image Dynamics ID8v.3's. The sub specs say (.6cuft, 34hz, with port dimensions 2"ID x 12"). The max space I have on all dimensions are (12"x16"x22"). Can somebody help me design this box and how to do the port?

Is it .6 cuft. per sub?

It says that on the spec sheet so I assume it's per sub... Here's a link to the sub spec sheet.

https://www.imagedynamicsusa.com/website/tech/ID8D4V3.pdf

I assume I would have the port in the middle of the 2 subs but don't necessarily know the how to do all of the dimensions.

Here's my first stab. The only dimension not listed is the height. I figured it would be 10" tall. Close?

Your design is too large.  If each sub wants 0.6 cuft ported enclosure you'll want to change the depth on the above design to something closer to 10" rather than 14".  Those subs are actually more suited to use in a sealed enclosure around 0.4 cuft.

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I thought I was at about 1.2 cuft combined for this box which seems right for .6 ea.. You say these would be much better off sealed? I'm trying to get as much spl out of these 8's as possible because it'll be in boat.

Take your inner dimenasion length X width X height and divide that by 1728 to get cubic feet.  Your design is roughly 22 X 14 X 10 = 3080 cubic inches, divided by 1728 = 1.78 cubic feet.  If your number are outer measurements, assuming you use 3/4" MDF then you are much closer at 1.26 cuft.  According to the Image Dynamics web site these subs are designed for sealed enclosures, but using them vented is an option as long as you do not overpower them.  The difference in SPL is shown on the page you linked and is the peak around the tuning frequency.

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Just a random thought. Could I do 4 of these ID 8's (2 back to back) in a sealed enclosure? Would that blow away the 2 ported 8's on the spl side? Can you have subs back to back like this? I have a Hifonics Brutus BX1500D that I need to use for these so it seems like I have enough power.       

No way, Jose.  Keep all the subs facing the same direction.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

what if i put a wall between the 2 sets. i suppose that would work, right? 4 sealed 8's better then the 2 ported?

You could design an arrangement with four woofers in the same airspace facing different directions.  It's called a "push-pull" setup.  My M&K home theatre subwoofer uses this kind of arrangement (M&K MX-350 MKII if you want to look it up.)  The basic theory is to wire one out of phase with the other so that both cones move in the same linear direction at the same time.  I'm not sure your design would work well as there are many other factors to consider other than simple air space, including precise damping, matching the woofers physical and electrcal performance (they must have the exact same compliance and displacement behavior) and using the correct amplifier and crossover.  Also, many push-pull setups use customized electronic controls to ensure the subs move in precisely the same amounts (like Community Sound's servo subwoofer series.)  So yes, it could be done.  Do I recomend it?  No.

Your next question is would 4 sealed woofers be "better" than 2 ported?  What do you mean by "better?"  Louder?

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yes, louder. 4 in a sealed enclosure would be louder then 2 in a ported enclosure, right? That push/pull thing is way too over my head. I have a Hifonics bx1500d so i think if i wire 4 in parallel I should have enough power for them all..

No.  If you look at the graph on the ID technical information page for this woofer, it shows that in a ported alignment the woofer produces about +3-4db above the SPL of the same woofer in a sealed alignment (around the tuning frequency of 34Hz.)  So 4 sealed (which will produce on average +3db more SPL than 2 of the same woofers sealed) would produce about the same SPL as 2 in the proper vented enclosure.  If "loud" is what you're after, I recomend using a single 12" in a ported enclosure which should produce more SPL than 2 of those 8's.

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unfortunately, i can't fit a 12 in the location. i am using the top of the box as a step to get into the boat. i previously had 2 10's firing down but that didn't work all that great so i'm want to go with 8's. so, 2 ported 8's will be equivalent on the spl side with 4 sealed... i guess that tells me which way to go.. i attached a pic of the 10's firing down and the location i need to put the box for clarity.

And why do you think those 8's will produce more SPL than two 10's?  All else being equal, in general more cone area = higher SPL.

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Just having the 10's firing down didn't sound very good at all in my opinion. I was hoping to have the 8's fire into the hull of the boat. People who have done both said it helped drstically. I can't go high enough to have the 10's firing out to the side..