The AV-8 Harrier utilizes a water injection system to enhance engine performance. The Rolls-Royce F402-RR-408 engine can produce up to 23,400 lbf thrust with water injection, compared to 22,200 lbf without it. This system features three injection ports that help cool the engine, allowing for higher RPMs and increased thrust. While the aircraft can operate without water injection, the system significantly improves its performance capabilities. Understanding this mechanism is crucial for comprehending the Harrier's operational advantages.