Page "Kliment Voroshilov tank" Paragraph 12

Nonetheless, because of its initial superior performance, the KV-1 was chosen as one of the few tanks to continue being built following the Soviet reorganization of tank production.

Due to the new standardization, it shared the similar engine ( the KV used a 600 hp V-2K modification of the T-34's V-2 diesel engine ) and gun ( the KV had a ZiS-5 main gun, while the T-34 had a similar F-34 main gun ) as the T-34, was built in large quantities, and received frequent upgrades.