Well, unfortunately, it's very difficult. You need to: Make the jbeam fit the new engine Make the DAE fit the new engine Make the materials and textures fit the new engine So... you have fun with that! Seriously though, If you want to research and try (trying is the best way of learning), try this page: https://wiki.beamng.com/Vehicle_Creation_Megapage
I don't know if this is still relevant but it's something: https://www.beamng.com/threads/tutorial-porting-engines-and-other-parts-inbetween-vehicles.28730/