It is not materialistically changed but radically repaired so as to accommodate new features it might not have in the previous version of the same engine. That said, engine is completely overhauled against possible faults and extended further, so that it features and function/work not the same old way.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
MustAskThe engine has been completely overhauled.It has been completely repaired. I would not expect its functions or specifications to be changed from the original.