Diesel engine performance and design characteristics are affected by applications. Understanding general performance characteristics and the relationship between engine system design and applications is important for diesel engine system design engineers. This paper is the Part 2 of a series of three companion papers (parts) addressing diesel engine applications (i.e., Part 1 - organization design and systems engineering; Part 2 - general performance characteristics; and Part 3 - operating and design characteristics of different applications). It illustrates important general characteristics with selected examples, and highlights key issues and commonalities of different applications that engine system design engineers need to know. Series design and multi-purpose design are summarized. Four core equations in an engine air system theory are proposed in order to reveal the parametric dependency of pumping-loss-related parameters. An interactive and coupled design methodology of engine-drivetrain system is developed. A formula of calculating the isentropic engine retarding power of compression-release brakes is proposed. Valvetrain dynamics and valvetrain system design are summarized. The interactions between valvetrain and turbocharger in engine air system design are revealed. A low-pumping-loss WE- VVA (wastegating elimination intake variable valve actuation) system is discovered by using simulation analysis with air system capability charts. A fundamental engine trade-off between peak cylinder pressure and exhaust manifold gas temperature is discovered. Selected references are provided in the review portion.