Whatever the reason -- I know you change your flame trap, but it could be the separation box under it that's clogged, especially if you don't use synthetic oil, which keeps it cleaner -- but on these B230 engines, there's a hocky puck sort of seal on the back of the head (not found in B23 and earlier cars), sandwiched between the head and the valve cover (you can feel it if you put your hand behind the engine, just by the firewall. The opening that the seal covers allowed the distributor to be installed there on other model cars that had room for it (only 240's need to have the distributor on the side of the engine because the firewall is too close). Pressure usually blows out this seal, the most common reason for a catastrophic, sudden loss of a large amount of oil, consistent with what you describe.

If you do find that it was this seal that blew out, you might want to know that IPD sells a little metal bracket that is easily installed (about 5 minutes of your time) as a precaution. Lots of folks on this forum have also made their own -- there's nothing special about the IPD version, except for the convenience of not having to make it yourself. I've never had a problem with these seals myself (I use synthetic oil, which even keeps my flame trap's screen clear) but I installed one of these brackets on each of my '93s, just as a precaution. You might want to install this, too, to prevent a reoccurance.