The calculated distance (air line) between Montemor-o-Novo and Portimão is approximately 106 miles respectively 170 kilometers.
By car or train, the actual journey to Portimão is certainly longer, as only the direct route (as the crow flies) between Montemor-o-Novo and Portimão has been calculated here.
Air line (approximately)
170 kilometers
92 nautical miles