Originally Posted by
Davef68
Presumably the theory is that it's easier to incorporate smaller engines into the existing nacelles than looking at changing the nacelles as well.
The nacelles are going to be all new (and most probably the struts). Modern fan-jet engines are much larger in diameter and tend to be significantly heavier due to the big fans and improved engine failure containment criteria.
As I understand it, there were two major issues with going with 4 big(ger) engines - ground clearance and (this from Ken V way back in this thread) maintaining the ability to carry/drop munitions from the wings.
Regarding ground clearance, back when we were looking at the RB211 replacement, I suggested perhaps they could get rid of those outrigger gear on the wing tips and incorporated something into the outboard engine nacelles.