The restriction method involves routing the gases through multiple turns.

• A. False
• B. True
• C. Only in diesel engines
• D. Only with turbocharged engines

Answer: (B)

The idea behind a restriction in a gas path is to create a deliberate resistance to flow. Routing the gas through multiple turns increases the energy losses from friction and turbulence, which produces a defined and controllable pressure drop across the path. This setup makes the flow behavior more predictable and easier to measure or calibrate, which is the essence of the restriction method. It’s a technique used to control or gauge flow, not something limited to a specific engine type, so it isn’t confined to diesel or turbocharged engines.