SQ Sub Box for Eclipse SW6210

The parameters as given don't  quite add up to the T/S model, as you'll note that the numbers for Qes, Qms and Qts don't compute, but I inputted into WinISD as best I could.  For the quest of having SQ, you should consider only sealed for this woofer.  The box is smallish, anywhere from 1 cu ft to 1.5 cu ft , net airspace.

That info is the EBP and is taken from Fs and Qes.  I only have the info you provided, .5 for Qes, and the Fs is consistent with Eclipse's website info.  That is a 41 EBP which is strictly into sealed territory for the reasons I will explain next.

Save yourself the enormous room required to vent this sub.  The box alone has to be rather big as you have seen with the models, and the port has to be equally long.  No matter how much you give it in airspace and port, you have a hard time keeping cone excursion below 12mm (12 mm Xmax is according to website).  When all is said and done you'll have 4 cu ft of heavy box for the purpose of very little *real* low end contribution in a vehicle situation.  Everything points to a simple sealed box for best results.

If you really want to give up 3.5 cu ft in your trunk for a sub, keep shopping and modelling potential subs until you find the one that will do justice to that kind of airspace.  This one, you could house two of them in that amount of room (sealed, of course).

For your earlier question, no, it is not bad to tune below FS.  Sometimes it is done for best SQ for a given woofer and knowing that very little output will come from the port itself.  It's one of those situations where you look at all the possibilities and pick the one that suits your purpose best.  And as for the direction of the port firing vs. the driver, in the trunk it's all the same any way it fires.  Some closer-up scenarios (maybe hatchback, def. truck cabs and small sports cars) should usually work best with the port and driver firing from the same baffle.

Keep the ratio of a slot port opening at no narrower than 8:1   Redesign and use the recommended 4" x 3" opening if you can find a way.  That will be the quietest and most accurate.

1/2" MDF is certainly sufficient for port construction.