box design for 1991 honda civic

I was hoping someone head a box design for a 1991 Honda Civic hatchback with about 8 cubic feet of airspace. I am going to run four 12 Hifonics hfi12d4's. I'm pretty sure it would take up the entire trunk. It's just hard with the shock supports and all the curves to get all of the measurements in there....so I was hoping that someone has been there done that already. Thanks!


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Proud To B Loud

I may have posted this under the wrong forum room as I did not get any response before. I am new to this site. I need to know about the best possible way to get the most cubic feet out of my hatch area for four 12 hifonics hfi12d4's. I don't really wanna go with fiberglass...maybe isobaric? I would really appreciate any input....Thanks!

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Proud To B Loud

We hear ya, we just don't know what to possibly tell you other than to get busy with the tape measure and keep your pencil sharpened while you draw out the plans.

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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.

I have a 93 honda civic and let me tell you its not humanly possible to get a 8 cuft box into that trunk even if you remove the folding back seat and try to get it into the trunk from inside the car it wont happen...I barely got my 4 cuft box into my car..

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4 12s cvr sealed
2 hifonics bxi608d
1 kinetic hc 800
alpine reciever
infinity kappa door speakers

unless you actually want to do the build IN your car. not recommended because you will have to destroy it if you ever want to take it out

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Wall it :) you can get the space walled . BTW this is a hatchback 4th gen we are talking about. not a 5th generation coupe or sedan.

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Even if you take out the back seat and attempt to wall of the civic a 8 cubic foot box is not going to fit threw doors and into the back of the car.No matter what the demintions of the box are it isnt possible.I had to take my front seat out and wrestle my 4 cubic foot box into the car from the passenger side door and then i had to get my box into the trunk from inside of my car witch was realy hard.....My whole trunk is the box now their isnt any room for even an extra cubic foot...So when i say it isnt possible it isnt possible trust me i tried to get some of my freinds boxes in there for the fun of it and they wouldent fit....building a box inside of that car isnt possible you have no room to work my freind...

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4 12s cvr sealed
2 hifonics bxi608d
1 kinetic hc 800
alpine reciever
infinity kappa door speakers

6thaveme wrote:

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Even if you take out the back seat and attempt to wall of the civic a 8 cubic foot box is not going to fit threw doors and into the back of the car.No matter what the demintions of the box are it isnt possible.I had to take my front seat out and wrestle my 4 cubic foot box into the car from the passenger side door and then i had to get my box into the trunk from inside of my car witch was realy hard.....My whole trunk is the box now their isnt any room for even an extra cubic foot...So when i say it isnt possible it isnt possible trust me i tried to get some of my freinds boxes in there for the fun of it and they wouldent fit....building a box inside of that car isnt possible you have no room to work my freind...

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you make a good point, but what J.Reed means is a WALL in the traditional sense that is built inside the vehicle from top to bottom and is meant to be permanent. anything else is just a big box

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To me atleast that seems very hard to do with that car..I have seen a few on youtube walled off but most local shops dont even have the experiance to do a procedure like that and most inexperianced box builders wont even come close to desighning that to fit rite and better yet sound good..

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4 12s cvr sealed
2 hifonics bxi608d
1 kinetic hc 800
alpine reciever
infinity kappa door speakers

6thaveme wrote:

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To me atleast that seems very hard to do with that car..I have seen a few on youtube walled off but most local shops dont even have the experiance to do a procedure like that and most inexperianced box builders wont even come close to desighning that to fit rite and better yet sound good..

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hahaha, the words "wall" and "sound good" should never be in the same sentence together. its really not that hard to build a true wall, it just takes time and patience to do it right. if you go to a shop, yes, they will tax you plenty. it would be hard to just design one on paper and then expect it to fit right. i would mock it up with wooden dowels and hot glue so you can get the angles right, but after you get your measurements:

step 1: build the floor. cut the wood to fit the shape of the floor in the car and anchor it with BIG bolts. i can't stress this enough. this is also for sound as well as safety because any movement of the box is lost output.

step 2: build the side walls. this is tricky because of space so you need to build the side walls with a 4 inch lip spaced away from each edge (top, bottom, front, and back edge) the same distance as the thickness of the wood you used for the floor and will use for the top. this will give you something to screw the top and bottom to without having to the sides to put screws (not possible because of space). also use a generous amount of liquid nails and brace every wall bigger than 24x24. once you do this you can slide the top on and screw it down from the inside.

step 3: build the front baffle. depending on how many subs and how big they are, you should layer the front baffle 2-4 layers of 3/4 or 1" MDF. screw them all together with liquid nails in between each layer. its important for the baffle to be layered because this is where all the holes for the subs will be cut so it will naturally be weaker. after thats done, screw it to the box from the front and back through that lip you pre-built into the side walls.

after this is done the back is still open so you can do any finishing touches like more bracing and maybe some threaded rods between the sides to keep tension and keep the box from flexing. and also run a bead of liquid nails around all edges to make sure you have a good seal and add strength.

last step is to add the back piece. make sure it is braced before you install it. and dont forget to make a hole to run speaker wires through.

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6thaveme wrote:

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To me atleast that seems very hard to do with that car..I have seen a few on youtube walled off but most local shops dont even have the experiance to do a procedure like that and most inexperianced box builders wont even come close to desighning that to fit rite and better yet sound good..

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I have fit 12 12s in a 5th gen civic hatch yes it can be done. 161db 97 Usaci 100 watt consumer world record. then in 99 did 6 15s 158db in a 5th gen civic hatch.

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on top of that i also did a 3 12s around 4.5 cube for my civic sedan the back seat was removed to get it in. Its the price you pay to get more square inches in there.

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soundnsecurity wrote:

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6thaveme wrote:

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Even if you take out the back seat and attempt to wall of the civic a 8 cubic foot box is not going to fit threw doors and into the back of the car.No matter what the demintions of the box are it isnt possible.I had to take my front seat out and wrestle my 4 cubic foot box into the car from the passenger side door and then i had to get my box into the trunk from inside of my car witch was realy hard.....My whole trunk is the box now their isnt any room for even an extra cubic foot...So when i say it isnt possible it isnt possible trust me i tried to get some of my freinds boxes in there for the fun of it and they wouldent fit....building a box inside of that car isnt possible you have no room to work my freind...

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you make a good point, but what J.Reed means is a WALL in the traditional sense that is built inside the vehicle from top to bottom and is meant to be permanent. anything else is just a big box

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This can also be done by using multiple encosures to make one big one. Say for instance with this one you could use 2 enclosures, secure them together and then make your baffle

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How would u put the two sepparate boxes together from inside the trunk glue each end and put them together from inside the trunk..very inspiring i would love to put 4 15s inside my trunk or even wall them off thank you soundsecurity for your advice it seems very difficult but you have to make sacrafices to get better in this game..I have a 93 honda civic 2dr coupe any suggestions on getting 4 15s in the trunk or inside the car...

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4 12s cvr sealed
2 hifonics bxi608d
1 kinetic hc 800
alpine reciever
infinity kappa door speakers

6thaveme wrote:

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How would u put the two sepparate boxes together from inside the trunk glue each end and put them together from inside the trunk..very inspiring i would love to put 4 15s inside my trunk or even wall them off thank you soundsecurity for your advice it seems very difficult but you have to make sacrafices to get better in this game..I have a 93 honda civic 2dr coupe any suggestions on getting 4 15s in the trunk or inside the car...

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Walled you should be able to do it. 4 15s in a civic coupe trunk no way.

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maybe 4 15s in a fiberglass box and using the extra space of the spare tire well but it still wont come close recommended airspace of any decent 15s. but either way the box will need to be built inside the trunk. now, if you wanted to take the back seat out and have the subs in a half wall with most of the box in the trunk but the subs in the cabin, that is doable

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6thaveme wrote:

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Even if you take out the back seat and attempt to wall of the civic a 8 cubic foot box is not going to fit threw doors and into the back of the car.No matter what the demintions of the box are it isnt possible.I had to take my front seat out and wrestle my 4 cubic foot box into the car from the passenger side door and then i had to get my box into the trunk from inside of my car witch was realy hard.....My whole trunk is the box now their isnt any room for even an extra cubic foot...So when i say it isnt possible it isnt possible trust me i tried to get some of my freinds boxes in there for the fun of it and they wouldent fit....building a box inside of that car isnt possible you have no room to work my freind...

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15 cu ft would fit in a wall of the civic.

8 cu ft would be hard to get in a SEMI-wall as what you are talking about since you know what you are talking about correct??

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Custom Enclosure Design

If you have cut the metal out between the cab and the trunk, you can easily get an 8 Cu.  Ft. enclosure into the car.  You might have to build it in the car, but you can get it in if it is in pieces.

Thanks for the advice i kinda figured i would never get 4 15s in the trunk of a coupe.Im going to get a new car soon and keep my civic on the road for competion so a wall seems very intresting....Im nervous that with the wall in my car there wont be enouph back pressure for the subs to sound good does anybody no how the wall will do on a meter.....

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4 12s cvr sealed
2 hifonics bxi608d
1 kinetic hc 800
alpine reciever
infinity kappa door speakers

6thaveme wrote:

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Thanks for the advice i kinda figured i would never get 4 15s in the trunk of a coupe.Im going to get a new car soon and keep my civic on the road for competion so a wall seems very intresting....Im nervous that with the wall in my car there wont be enouph back pressure for the subs to sound good does anybody no how the wall will do on a meter.....

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Considering the loudest vehicals in SPL are walled what do you think that says for how they do on mics? If your asking for a number there are way to many facters to even give you an estimate. Power, enclosure, port tune, electrical upgrades, dampening, layout and not to mention the drivers them self.

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6thaveme wrote:

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Thanks for the advice i kinda figured i would never get 4 15s in the trunk of a coupe.Im going to get a new car soon and keep my civic on the road for competion so a wall seems very intresting....Im nervous that with the wall in my car there wont be enouph back pressure for the subs to sound good does anybody no how the wall will do on a meter.....

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are you talking about using the trunk as the box? is that why you mention back pressure? building a wall is not really different from building a normal box. its still completely enclosed except for the port. you design it so that it fits in whatever car you want and tune it to just below the frequency you want to burp in competition. the output you get from a wall depends on a lot of factors but the main ones are: efficiency of the box at the burp frequency, power, cone area, physical box strength( any flex is lost output), and strength of the vehicle itself. this is why most high spl vehicles are filled with reinforcing struts to keep the walls and roof from flexing under high pressure.

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What i meant to say by backpressure is bass reflection.For instance when i had my box laying on my back seat instead of my trunk i got felt the bass much more when the sub was fireing twords the side of my car compared to the sub fireing twords the front of my car.That tells me the bass waves are bouncing back much faster when the box is faceing twords the side of my car because the bass waves have less room to travel.So if i walled off my car my issue would be that the bass waves would have to stretch out further to reflect off the front of my car..

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4 12s cvr sealed
2 hifonics bxi608d
1 kinetic hc 800
alpine reciever
infinity kappa door speakers

well, you can feel more bass but its not necessarily louder on a meter. it is possible to feel or hear a difference when you change the placement of a sub but that is mostly due to the difference in distance that the wave(s) have to travel to make it to you. thats why you might get completely different results from facing the subs towards the back of the trunk instead of towards the front, but that can go either way depending on the design of the box. and bass waves dont "stretch" under normal conditions, the wave length is set depending on the frequency.

and it would be hard to give you an answer about reflections in your car because different materials either absorb or reflect or resonate certain frequencies. in an ideal setting you would want everything to absorb to get the best sound quality but if you can get your hands on a RTA you can measure what frequencies get resonated and tune your wall to that frequency to give you an added bit of output. this is what the real high output competitors try to do, they use everything to their advantage.

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6thaveme wrote:

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What i meant to say by backpressure is bass reflection.For instance when i had my box laying on my back seat instead of my trunk i got felt the bass much more when the sub was fireing twords the side of my car compared to the sub fireing twords the front of my car.That tells me the bass waves are bouncing back much faster when the box is faceing twords the side of my car because the bass waves have less room to travel.So if i walled off my car my issue would be that the bass waves would have to stretch out further to reflect off the front of my car..

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waves bouncing faster??

The speed of sound does not change from the position of the enclosure.

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Custom Enclosure Design

I kno it doesnt change but if you have the enclosure in a position where the waves meet a surface much faster compared to a diffrent position you will feel the bass much more.

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4 12s cvr sealed
2 hifonics bxi608d
1 kinetic hc 800
alpine reciever
infinity kappa door speakers

Depends on the enclosure and the install...Can't say that with any certainty

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Custom Enclosure Design

just had a thought, i have no idea if it is true or not but maybe with the sub hitting closer to a wall it puts more energy into a wall and some of that energy gets transferred throughout the entire car by the walls thus turning the whole car into a speaker through the walls vibrations. but, i really dont know, its just a thought.

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