The size of the engine varies depending on how many liters it has, it would be nice to see it in beamng drive
I wish swapping an engine based upon their displacement is THAT easy, you have to consider a lot of things, ie. their actual dimensions (which many smaller vehicles will NOT fit), as well as their maximum torque and RPM limit before they are irreversibly destroyed.
Of course, as far as I know, the engine model has no internal parts, revolutions, rotation of the crankshaft, are these numbers, or not?
Internal parts influence the JBeam's RPM (revolutions), power, torque and durability (see -long block), they are numbers in the JBeam file not the flexbodies engine models.