Modifying explosions?

How does one make explosions a) larger b) the after effects (smoke column) last longer?
I've opened .fx files with WordPad - what attributes alter duration of smoke?
Looks silly when the after-effects of a 500lb bomb strike on a building disappear after a few seconds...
J_o_J
I've opened .fx files with WordPad - what attributes alter duration of smoke?
Looks silly when the after-effects of a 500lb bomb strike on a building disappear after a few seconds...
J_o_J