View Full Version : Help me with Cu Ft in this design...

scoob8000

03-26-2009, 08:45 PM

My math *****, I just cant wrap my head around measuring cubic space with all these angles. :crap:

Here's a plan that I'm thinking about basing a build off of. I'm only going to be using one sub, and making it narrower (40" wide) to get to my proper air space..

http://i241.photobucket.com/albums/ff292/ItsAdam1/237959_80_full.jpg

psych0ticnemes1

03-27-2009, 10:15 AM

That looks like it is going to be difficult to port. Maybe you should consider aero ports firing up or out the front?

schrummy

03-27-2009, 10:30 AM

i got 4.36 cubic ft. i used your messurment as the outside of the box.

x2 on areo ports

psych0ticnemes1

03-27-2009, 10:34 AM

i got 4.36 cubic ft. i used your messurment as the outside of the box.

x2 on areo ports

If this is the total area he has to work with, the wood will take up quite a bit of room within those dimensions as well.

dman4486

03-27-2009, 10:36 AM

If this is the total area he has to work with, the wood will take up quite a bit of room within those dimensions as well.

when he said he used the dim as outside dim, I would assume that means he included the wood's displacement.

schrummy

03-27-2009, 12:46 PM

^^^^^^^your righit.

i did take into account the wood displacment

scoob8000

03-27-2009, 06:04 PM

i got 4.36 cubic ft. i used your messurment as the outside of the box.

x2 on areo ports

Beggers can't be choosers, but would you mind showing me how you worked that out? I know you kind of have to break it apart in sections, but maybe I'll learn from example. :)

That's gonna give me more space than I though. I'm only going to be running a single 12" Lethal Injection. This design box will fit under my rear deck. I'm planning on making it narrower and incorperating some kind of amp rack on either side of it. Or put the sub on one side, and amp rack on the other.

I had thought about doing slot port, but putting the port above the sub horizontally. Or using precision ports and porting into the cabin. Undecided yet..

scoob8000

04-03-2009, 06:03 PM

I really need to thank schrummy for the help on this! We did a little commuincating via PM and he was a great help. Here it is for those trying to figure out airspace in a non-square box!

srry for the large pics

to find the airspace inside of the box you have to find two separate boxes and add them together. the rectangle box and the wedge box. first i started with the box you presented me

http://post.mach-five.com/posted/1/Car_Stuff/stockboxwithmessurments.jpg

then i made it 2 separate boxes to give me an idea.

http://post.mach-five.com/posted/1/Car_Stuff/stockboxfinding2boxes.jpg

from there i had to add the wood thickness

http://post.mach-five.com/posted/1/Car_Stuff/stockboxwithmessurmentsafteraddingw.jpg

then i made the 2 separate boxes again

http://post.mach-five.com/posted/1/Car_Stuff/stockboxfinding2boxeswithwood.jpg

using the measurements i took the upper box which is 6*19.25*38.5 multiplied them together to get 4446.75 cubic inches then i divided that number by 1728 which is 12*12*12. this will convert it into cubic ft. which is 2.573 cubic ft.

now the bottom

it is a wedge shape so you cant just multiply it out. first you take the top piece of the wedge which is 13.375 and add the bottom piece which is 5.375. together they are 18.75. now you divid this number by 2. this will give you the average lenghth of the top and the bottom. that number is 9.375. now you take that number by the side (9.5) and then multiply it by the length 38.5. together they are 3428.90625 cubic inches. now you divide by 1728 to bring it to cubic ft. 1.984.

now all you do is add the two boxes together. 2.573+1.984=4.557. this numer is different because i didnt take as much time to take into acount the length of the angle of the slope of that back plate.

hope this helped you. any questions just let me know.