cylindrical enclosure

[adalos 10+ year member]

I'm going to build a fiberglass enclosure in my 2003 celica. I want to keep everything hidden, so my plan is to build the enclosure in the spare tire well:

unlike that guy, i am going to take the tire out and actually make a fiberglass enclosure with an MDF top.

i spent a lot of time looking here for people who have built cylindrical enclosures but pretty much came up empty. i have seen some mention that a cylinder should actually perform better than a box or rectangle due to how waves bounce off flat walls vs rounded ones.

i'm going to be making a sealed 1.25ft3 enclosure, so check if my math is right here:

wheel well dimensions:

width = 20 inches

depth = 9 inches

volume of a cylinder = Pi x Radius^2 x height

3.14 x .833^2 x .75 = 1.65 cubic feet

So that's the total cubic feet of my wheel well if i did the whole thing. I'm only looking to make a 1.25 cubic foot enclosure, so in order to achieve 1.25, i need to find the appropriate height to make the enclosure:

3.14 x .833^2 x X = 1.25

X = 1.25/2.18

X = 0.57 (feet) = 6.88 inches = ~ 6 7/8 inches

So I'll probably just go with an even 7 inch height to make up for the thickness of the fiberglass.

This is a rough photoshop job of what I'm trying to do:

As I said, I want everything to be hidden, so the trunk carpet will be going back over it. My plan is to mount a raised wooden square around the sub and then mount metal pipes as a fabricated grill to both keep the carpet a few inches above the sub and to protect it from anything that gets put on top of it (groceries mainly). the hatch that you see will have it's center cut out to allow the sub output to go through without any impedence.\

anyhow, that's my plan. does this sound functional and feasible? any issues you can see me running into? i might end up raising the floor a little as well, depending on how far things stick out, and to possibly get my amp and wiring all under there but with enough airflow to not overheat. i want people who look into my car's hatch to see what appears to be nothing but stock flooring.

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[jrz126 10+ year member]

It should work, but you'll probably need to fiberglass it if you want it to sound good. I made one awhile back. I had my subs angle up alittle, but you can change it to whatever you want. I have some info here:

http://www.personal.psu.edu/jrz126/fiberglass.htm

 

[adalos 10+ year member]

as in fiberglass the whole thing? i plan on fiberglassing the bottom and sides and having an MDF top piece. the picture with the sub mounted on the well hatch is just an example pic i found to show what the celica spare tire wheel well looks like.

 

[jrz126 10+ year member]

Yeah, MDF on the top would be fine. I used a pretty large piece on mine. You'll have to make sure you get a good seal between the MDF and fiberglass.

 

[adalos 10+ year member]

thanks for the info. does your sound deadener matting lay underneath your enclosure as well?

 

[jrz126 10+ year member]

No, I removed it from the tire well. I think I should have left it in there though, it rattled quite a bit. I dont think I used enough layers of fiberglass either.