Which term describes resistance to flow in the exhaust or system that adds to the cylinder load?

Which term describes resistance to flow in the exhaust or system that adds to the cylinder load?

• A. System pressure
• B. Back pressure
• C. Ambient temperature
• D. Viscosity

Answer: (B)

Back pressure is the resistance to the flow of exhaust gases in the exhaust system, and it adds to the cylinder load because the piston must push against that opposing pressure during the exhaust stroke. When the exhaust path is restricted, pressure builds up and the engine has to work harder to expel the spent gases, which reduces scavenging and efficiency. The other terms don’t describe this specific resistance: system pressure is a general pressure inside the system, ambient temperature affects air density but not flow resistance in the exhaust path, and viscosity is a property of the gas itself, influencing flow but not the external obstruction behind it.

Back pressure is the resistance to the flow of exhaust gases in the exhaust system, and it adds to the cylinder load because the piston must push against that opposing pressure during the exhaust stroke. When the exhaust path is restricted, pressure builds up and the engine has to work harder to expel the spent gases, which reduces scavenging and efficiency. The other terms don’t describe this specific resistance: system pressure is a general pressure inside the system, ambient temperature affects air density but not flow resistance in the exhaust path, and viscosity is a property of the gas itself, influencing flow but not the external obstruction behind it.