enclosure w/woofer magnet exposed?

No "name" that I'm aware of.  If it would be a sealed enclosure with the sub mounted normally, it would still be a sealed enclosure with the sub mounted reversed.  You should figure volume just like you would for a normal enclosure, an since most of the sub is now outside the box and the cone is extending outwards, I would guess the speaker volume inside the box would be negligible. 

Mike

I asked this same thing just a few days ago, and did some research.  I couldn't find any real information on pros or cons, but people that responded said it was fine.  I just made an enclosure to ount two JL10's this way.  I did it for space considerations though, and to hide as much of teh drivers as possible.  I'br only listened to the box for 15-20 mins, and not cranked it up really high yet.  Sounds just fine from what I've heard.  I never had both 10's together in sealed enclosures before, so I can't comment on how the sound compares directly.

It seems like you have less surface area to radiate sound energy from, what with the dust cover on the inside and all.  But your coils should stay nice and cool since they are out in the open...

Sorry I couldn't give you more definitive information.

Mike

I decided to go "stealth" and wanted my enclosure as invisible as possible.  I ended up making a flat box that covered all of the available floorspace.  The box was so thin that a lot of the sub would have to be exposed still.  I figured if I flipped the sub over, the "largest" part of the sub would be hidden, so now I just have to disguise about 4" of motor/frame that are sticking out of the box.

Mike