Hey there,
I just happened to look at this, and if you are still looking for a good fuel explosion, I can help.
I did a script that produces a pretty spectacular fuel truck explosion; when the truck is killed (or takes enough damage) it uses a randomized setvelocity command in conjunction with a camcreated LGB to launch it, and drop created fire and smoke trails behind. The fuel actually sets anyone unlucky enough to be around on fire (like napalm).
I also did an exploding ammo truck script that features drop created 'tracers' to simulate rounds cooking off, if you are interested.
-Grendel