Replacing a cast iron pulley with an aluminum pulley is used to decrease what?

Replacing a cast iron pulley with an aluminum pulley is used to decrease what?

• A. Parasitic drag
• B. Engine displacement
• C. Ignition timing
• D. Oil pressure

Answer: (A)

Reducing the rotating mass of belt-driven accessories lowers the load the engine has to overcome just to keep those accessories spinning. A heavier pulley stores more kinetic energy and requires more horsepower to accelerate and maintain speed, so more of the engine’s power is spent on this useless spinning load. By using a lighter aluminum pulley, that parasitic load is reduced, freeing more of the engine’s power for productive work. Engine displacement, ignition timing, and oil pressure are not affected by changing pulley material, since those are determined by engine design, ignition systems, and the lubrication system, respectively.

Reducing the rotating mass of belt-driven accessories lowers the load the engine has to overcome just to keep those accessories spinning. A heavier pulley stores more kinetic energy and requires more horsepower to accelerate and maintain speed, so more of the engine’s power is spent on this useless spinning load. By using a lighter aluminum pulley, that parasitic load is reduced, freeing more of the engine’s power for productive work.

Engine displacement, ignition timing, and oil pressure are not affected by changing pulley material, since those are determined by engine design, ignition systems, and the lubrication system, respectively.