Subwoofer Stealth Fiberglass Enclosures
 

Hi everyone, this is my first post so I thought I could contribute something I recently did. Below are some pics of my stealth fiberglass enclosure setup which retains the spare tire and doesn't use up any extra trunk space. Nissan did a terrible job making full use of the trunk space, putting those oversized styrofoam things on each corner, one of which holds nothing but a bolt. These boxes fit where those pieces did and I was able to get about 0.62 cubic feet of volume for each one and roughly 5.5" mounting depth, more than enough for 8" subs, and probably enough for many 10" subs (I believe you can fit 10" in each corner instead of 8", and I almost attempted it halfway through when I realized with some measurements that it could work, but I didn't want to cram anything). Given that doing two boxes is twice the work of doing one, if you attempt a similar project you might want to attempt the 10" to save some time/effort/money. I liked the idea of twin 8" as it's kind of unique and after listening to just one 8" installed, I realized I was gonna have more than enough boom and that it was plenty deep. I actually would have been perfectly happy with just one but I went ahead with the second one since I'd already bought everything. This is getting to be a lot of text so I'll just put the pictures now and you can read more details below them if you are interested:

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I intentionally selected the lowest frequency range subs I could find, which are Image Dynamics ID8's that were designed with a 22 Hz Fs. They are rated at around 150Wrms each, but in reality have been said to handle well in excess of that. These things are amazing, thundering well into the low 30 Hz range and even into the 20's. I made the boxes bigger than needed (ID says only 0.3 cu ft is required and 0.5 is "large") but I believe this gives them even better low-end extension. Qtc if I remember I calculated at about 0.6, providing quite a flat response that should satisfy most audiophiles. Together they replace a 10" bass tube installed by previous owner which was ported and took up 1/3 of the trunk. They're a bit louder than that ported 10", which is about right since they're being fed together twice the wattage but in sealed boxes. I have a Rockford Fosgate amp running at 600Wrms @ 2 ohms. I stole the amp mounting idea from another member on here who posted his setup some time ago (someone give him a shout out if you remember because I don't). For the grills, I found some "heavy duty" ones (16 gauge I believe) which you could literally stand on if you wanted. I had to weld on some strips of sheet metal and drill holes as they had no flange (be smart and buy ones that have a flange), and then I used 1" aluminum spaces to mount them to the subs using longer screws and the subs own mounting holes. In planning the whole thing I decided it would be best to give the subs some breathing room under the floor/carpet, so I made the boxes about 1" lower than the bottom edge of the outside plastic trim. As you can see, I only had to cut a small arc out of the styrofoam piece on one side. The top of the styrofoam is about flush with the top of the grills, and the cardboard floor piece then sits even with the bottom edge of the trim panels. The amp also gets about an inch of breathing room above it. The end result is a trunk that looks and functions just like a completely stock one. You can throw things around back there without worrying about damaging subs. You can fit the big roll-around checked luggage. Etc. I have some vids on youtube explaining the basics of doing the fiberglass work a little better so you can search for those if you want (same username as here).

Nice work! That is a pretty sweet setup. I am a big fan of subwoofers being hidden/well integrated into the interior of the vehicle. I did the whole big square/rectangle subwoofer boxes in several vehicles in my late teens/early twenties, and the space those setups take up is a big issue. Plus they just look gaudy or tacky IMO. I really dig this type of setup that you made, and the fit looks great! :Thumbup:

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Damn that's awesome! I would order some duratex and give them a real nice professional finish.

Thanks for the compliments! This was my first time working with fiberglass so I'm really happy with the results. The process was fun but a bit miserable too with all the itchiness and mess. Having gone through it, spending many hours on each one, I would gladly pay for custom boxes, but as far as I know, nobody makes them for these locations.

SeeThruHead, that's a good idea. I bought some plasti-dip spray and I was gonna put a thick layer on them to help dampen any possible vibrations, but once I got carpet, trim, and everything reinstalled I found that vibrations were very minimal, except when I really crank it. So I never got around to applying the stuff and probably won't.

DieselKrampus, I agree. In this car where there is precious little cargo space, a sub box of modest size almost makes the trunk useless. With the bass tube right behind the bar, fitting my large roll-around luggage was a pain. I had to turn it sideways, unzip and open out the top, and put the bottom edges up on the interior trim by the shock towers at a perfect angle to clear the hatch lid. It was ridiculous. That's really what prompted the whole project. I used to have a 3000GT and never had an issue with cargo space, and I had a 2 cu ft box with a 15". Those cars had plastic storage trays under the carpet and beside the spare tire which is what they should have done with this car. And of course the rear seats folded down making even more space when needed. This one modification has made me much happier with my 370z.