Looks like I found the problem. Urfisch's mod overwrites the particles.dat and Materials.dat files in the Library folder. In each case the files were slightly smaller in size than the Racerboy mod. So I put the Racerboy versions back in, and I get nice firey explosions with no rends in the space-time continuum. Flat earthers be damned! It looks like the laws of Physics will live to see another day!
