This is the last of a four video series from an April 2022 tour of SpaceX Starbase with Elon Musk and Everyday Astronaut Tim Dodd. This episode examines the Raptor engine in detail, showing the evolution of the Raptor 1 to the simpler and more powerful Raptor 2, describing the challenges in starting an engine with such a complex power cycle, detecting malfunctions before they become catastrophic, injector design, and “secret sauce” not visible from the outside that SpaceX does not disclose.