currently, you are creating the Format instance in the Engine constructor, which is most likely not what you want (your current example would throw a NullPointerException.
secondly, you have 2 synchronization concerns. first is the correct publication of the format instance. you don't do this currently. you should either use class initialization (instantiate the format instance on class create) or make the format member volatile in order to correctly publish the format instance.
secondly, if your format instance has mutable state, then you should make the FormatV1 methods themselves synchronized. making the caller synchronize on the object before using it is a very bad design.