  The four-quark condensates appearing in QCD sum rule are calculated
nonperturbatively in a realistic QCD motivated extended Nambu-Jona-Lasinio
model. The calculation is in the framework of the effective potential for local
composite operators up to next-to-the-leading order in the 1/N expansion in
which the non-factorized parts of the condensates are included. We show in this
paper the possibility of explaining the phenomenological enhancement factor
$~\kappa=2.4~$, needed for fitting the data in the factorization approximation,
as the contribution of the non-factorized parts of the four- quark condensates.
