The engineering production function and engineering cost curve are concerned with the production costs. They have nothing to do with the managerial costs. The engineering production function is confined to some techniques of production which state that the factor of the production can be substituted up to a specific limit. In other words the engineering production function is kinked with Isoquant which sate that factors of production are substitutable in the range of kinked part of Isoquant.
We cant say perfectly engineering cost curve. I complete my education from Nagpur engineering colleges and I learn there that, they technically state the affairs of quantities of factors of production are assessed.