Le is measured in mH and affects the upper frequency response of the driver. You should be able to leave it empty and model the lower frequency response of the box without it though.
However he still has his audio equipment, If anyone could tell me the definition of Le, or a way to find the values of it my self.... I would greatly appreciate it.
Le can be measured with this:
http://www.parts-express.com/pe/showdetl.cfm?partnumber=390-806&utm_source=Bazaarvoiceps
What is Le?
it is voice coil inductance, normally referenced to 1khz for a woofer and 10khz for a tweeter.
Most cheap car audio subwoofers will have a big inductance, so you can expect as much as a 5db peak around 50 to 100hz in the frequency response. Likewise, most cheap car audio subwoofers will have a high qts, so you can expect a very sharp knee at system resonance. The driver you chose has a qts = .52 which is not great, but certainly more usable in a box than the typical car sub.
My suggestion would be a 2 cu ft sealed box to maximize power handling. You should be able to pour around 85 to 100w @ 8 ohm into it (basically whatever car amplifier specs itself to be about 400w will deliver this usefully)
Q is slightly high at .827, but I wouldn't fret. The cabin gain will raise efficiency below about 60hz which will affect that actual sound heard. Besides that, I very much suspect an inductance hump that I mentioned earlier. This is probably 1 to 3db, probably centered around 80hz. Finally there`s your crossover low pass, which again affects the frequency response in that same frequency range.
If I had to give you any real advice it would be this:
have the capability to measure the response between 20 and 200hz. Once you can measure it you want to be able to tame peaking in the response with equalization.
