I got plans for my 1999 Dodge Ram 1500 conversion van with four captain's chairs and a rear electric reclining couch.
The place I want to put the woofer box has max dimensions of 48" wide, 10.5" high, and 7" deep. These are the absolute limits of the outside dimensions of the box. Can't make it any larger without it getting in the way. It's going to go under the front edge of the rear couch. If it is any deeper, people's legs will rest on the upper corner.
I had my heart set on four 8" woofers which require 0.55 cu ft each. Two will be on each side, with the enclosure walled off in between the pairs - the amp driving these four woofers (Panasonic CY-PA2003U) will have each side driving a pair of woofers, and a 6x9 (one on each side, mounted in the wall just ahead of the couch). The front part of the van will have its own amp, same model.
Problem is, when I do the math for a sealed box, I come in below the 1.1 cu ft per side that each pair of 8's will need (documentation calls for 0.55 cu ft each). I might get to 0.89 cu ft per side depending on what board thickness I use, but I was hoping to use 3/4" MDF. Would 5/8" thick MDF be feasible for four 8" woofers?
So, it comes down to a ported box if I want to make the available space work. This port calculator page I found seems to require a port length that would simply not be possible:
http://www.carstereo.com/help/Articles.cfm?id=31
With two 8" woofers, and a tuning freq of 40 hz, the first part gives me a port diameter of 4 inches.
Entering this value into the Vent Length calculator at the bottom half of the page, keeping the tuning frequency at 40 hz, and the enclosure volume at 0.89 cu ft, I get a Vent Length of 20.86 inches! Bah!
Is it simply not possible (or convenient) to vent a box that small with two 8" woofers?
On the other hand, a sealed box that is 20% smaller than it should be - is that necessarily a deal breaker? Doesn't it provide some measure of protection against cone overexcursion? Will it really be taking that much performance out of the woofers? Will it be "good enough" is what I'm getting at, I guess. I am not looking for "competition" performance or anything, just a good kick drum feeling like in the first part of Robert Palmer's "Addicted to Love" I don't even need it to go really low.
I'm hoping to get away with not porting the box.
Thanks very much for any insight!
p.s. - Gear I have ready to install in the van:
Head unit - JVC KD-DV5300 Mobile DVD Player
(2) Bravo CNIC OVR-104 Overhead LCD Monitor (1 front, 1 rear)
(2) Panasonic CY-PA2003U 2-Channel Amps
(2) Clarion ProAudio SRH292HX Tweeters (front, going to put bass-blocking caps on the Pioneer 3 1/2"s already in the dash, and hope for the best)
(2 pairs) Panasonic CJ-A6933 3-Way Speaker (1 pair front doors, 1 pair rear walls)
(4) Boss Chaos CH8 8" Subwoofers (cheap, but effective)
