The self-accelerating speed in engine starting is best described as?

The self-accelerating speed in engine starting is best described as?

• A. Idle speed
• B. Self-accelerating speed
• C. Maximum operating speed
• D. Ground idle speed

Answer: (B)

The self-accelerating speed is the speed at which the engine can continue to accelerate on its own after ignition, without continued help from the starter. Once fuel and spark are available, the combustion torque adds to the starter’s input until it exceeds the engine’s losses, allowing the RPM to rise automatically toward running speed. This threshold is higher than idle but not the maximum operating speed, marking the transition from externally assisted rotation to self-sustained operation. Idle or ground idle describe stable low-speed conditions, while maximum operating speed is the upper limit; neither captures the moment when the engine takes off under its own power.

The self-accelerating speed is the speed at which the engine can continue to accelerate on its own after ignition, without continued help from the starter. Once fuel and spark are available, the combustion torque adds to the starter’s input until it exceeds the engine’s losses, allowing the RPM to rise automatically toward running speed. This threshold is higher than idle but not the maximum operating speed, marking the transition from externally assisted rotation to self-sustained operation. Idle or ground idle describe stable low-speed conditions, while maximum operating speed is the upper limit; neither captures the moment when the engine takes off under its own power.