What happens during the "power stroke" phase of an engine cycle?

What happens during the "power stroke" phase of an engine cycle?

• A. The engine is idling
• B. The air-fuel mixture is ignited, pushing the piston down and generating power
• C. Fuel is injected into the cylinders
• D. The exhaust valves are closed

Answer: (B)

During the power stroke phase of an engine cycle, the air-fuel mixture that has been compressed in the cylinder is ignited. This ignition occurs due to the spark plug firing in gasoline engines or from the high temperature of compressed air in diesel engines, causing a rapid expansion of gases. As these gases expand, they push the piston downwards with significant force. This downward movement of the piston is what generates the power necessary to turn the crankshaft and ultimately drive the vehicle. This phase is critical in converting chemical energy from the fuel into mechanical energy, which is what powers the engine and, ultimately, the vehicle itself. The efficiency and effectiveness of this power stroke significantly impact the overall performance of the engine, including its horsepower and torque output. Hence, understanding the dynamics of the power stroke is essential for anyone studying advanced engine repair and operation.

During the power stroke phase of an engine cycle, the air-fuel mixture that has been compressed in the cylinder is ignited. This ignition occurs due to the spark plug firing in gasoline engines or from the high temperature of compressed air in diesel engines, causing a rapid expansion of gases. As these gases expand, they push the piston downwards with significant force. This downward movement of the piston is what generates the power necessary to turn the crankshaft and ultimately drive the vehicle.

This phase is critical in converting chemical energy from the fuel into mechanical energy, which is what powers the engine and, ultimately, the vehicle itself. The efficiency and effectiveness of this power stroke significantly impact the overall performance of the engine, including its horsepower and torque output. Hence, understanding the dynamics of the power stroke is essential for anyone studying advanced engine repair and operation.