Dropping an engine looks like a quite stupid idea :
- you might hurt someone on the ground
- yor CG will probably be out of limits afterwards (most twins with wing mounted engines have weights attached to the pylon during production to avoid them falling on their tail, for fuselage mounted engines it´s even worst)
To learn more about blow bolts you should look up some space technology pages in the web (maybe the NACA-report server contains some usefull information) because they are widely used in spacecraft design.