hi there , this aint gomma be much help to you really but i have no idea what the weight of the engine is , but my suggestion is to forget about taking it in the boot as i really doubt it will fit in physically . even if it did it wont be good to get it out/in without damaging it , or your hatchback car.
the better way would be to either put it in a decent trailer and take it that way , or hire a transit or something similar, again the problems would be getting it out easily.
Larry