jbeam question

i wanna ask how enlarge car's part (for instance barstow engine) and fit that part on other vehicle????

 

You can open several jbeam and move easly nodes with BNeditor, that can be found in BNG system folder -> C:\Program Files (x86)\Steam\steamapps\common\BeamNG.drive in Windows system.

-You can export the whole or selected objects from blender to Wavefront *.OBJ that can be imported as reference mesh in BNeditor. You probably must make some tests to have the right scale and correct orientation of your object (correct is -Z forward and Y up).
-Move the nodes carefully, with round value 1.0 = 1 meter (use value like 0.025 rather 0.025484, easier value to remember for moving nodes in other concerned jbeams) and open other jbeam to check if nodes don't collide.
-A few of patience is a must ;-)
-Some slots creating disturbance can be tentatively disconnected (simply with comment in jbeam file -> // )
-Work step by step.
-Don't forget to save your file frequently when you make changes a little perilous, they can broke the mod (jbeams are highly susceptible...lol, really).
-Have a lot of fun with that, it can be rock'n'roll

...and when you become good enough you can also make the 3d projection in your mind and move directly the node in jbeam with Notepad++. For moving a simple position of node it's not so hard!