Here is an example how we can use Live Boolean in ZBrush 4R8. The feature is super handy- first time we can have accurate real time preview of boolean operation. We can keep working with the mesh pretty much infinitely by adding substract, union or intersect subtools, and we can also arrange these to boolean groups. When are are finished, we can create boolean mesh. This will create new tool for us, leaving the working tool intact. Pretty nice ZBrushey approach to booleans.
Check out the video below on how to create motorcycle engine kind of shapes using Array Mesh and Live Boolean in ZBrush 4R8.