well this is why im not sure what to do. the sundown site says 1ft^3 is ideal for sealed, but thats on rms power. im overpowering them a little so should i shrink it down or does that not matter with sealed boxes? on d4s one guy told me to do 2.25 per sub but the site says do that for lower power levels, and again, im overpowering them.
Give em a cube each after displacement then. A sealed box normally has higher box rise than a ported box. So the actual power that they're seeing is probably a little less than you're thinking. Sealed boxes aren't like ported boxes. They have more cone control due to the fact that the box isn't open, so when the sub undergoes excursion. the vaccum within the box will make the sub work harder. Ported boxes don't have the cone control that sealed boxes due, so you try to recreate the effect by shrinking the box (with more power)and making it bigger (with less power).
You won't really know until you try it. And more than likely you're going to get different answers across the board. You can always go big and shrink the box down if you want to experiment, but you can't do vice versa. If you build your first box with the intentions of trying to find the ratio that sounds the loudest or the best to your ears, build it big, and make it easy to dissasemble by using caulking instead of resin or wood glue. Once you find that, after a little trial and error. Build a badass box that you know will work the first try, sound badass, and get loud.
well then the minimum i would be able to do would be at least 6.5 cubes (with little to no bracing) and i wouldnt be able to fit that. even if i did build it in the trunk it would be a pretty awkward shape and a little harder to calculate the volume if i wanted to still have it sealed off. looks like im stuck at a 142.0 until i can figure out how i can make my box more efficient . or until i sack up and decide to try burping at .25.
6 cubes Sounds about right for a pair of 12s. 142 ain't bad. You're better off using the proper airspace on a sub than compromising airspace to fit bigger subs. So if it means running 10s or a single 12 to be able to fit a 4th order in your trunk... It can't hurt to try it. Wood is $30 a sheet and time is time.
EDIT: Don't burp at .25 ohm.
i dont need to have a 4th order, i was just trying to find a way to get bigger numbers
im really not sure about that big of a box though. 3 cubes each is even bigger than recommended for underpowering them and im going to be adding even more power soon.