Providing Support:
Engines are 'built' to support or enable the production of power. Building an engine takes many forms and usually involves replacing stock components with high-performance versions of those parts. In most cases, upgraded components for building engines are not developed until a specific weak point has been identified. The process for manufacturing and releasing engine build parts requires a substantial investment in terms of time and money, as well as extensive research, development, prototyping and testing.
Common examples of built engine components are forged connecting rods, pistons, valve springs, and cam shafts.