Retarding spark timing increases torque and horsepower.

Retarding spark timing increases torque and horsepower.

• A. True
• B. False
• C. Not sure
• D. N/A

Answer: (B)

Spark timing is about when the air-fuel mixture ignites in the cylinder relative to the piston position. When timing is advanced, the spark fires earlier in the compression stroke, so combustion starts sooner and peak pressure occurs earlier in the power stroke. This increases the force on the piston and boosts torque and horsepower up to an optimum point. Retarding timing, firing later in the cycle, moves the peak pressure closer to the end of the power stroke, reducing the effective pressure on the piston and thus lowering torque and horsepower. While retarding timing can help prevent knock or protect the engine under high boost or aggressive conditions, it generally decreases power. So the statement is not correct.

Spark timing is about when the air-fuel mixture ignites in the cylinder relative to the piston position. When timing is advanced, the spark fires earlier in the compression stroke, so combustion starts sooner and peak pressure occurs earlier in the power stroke. This increases the force on the piston and boosts torque and horsepower up to an optimum point. Retarding timing, firing later in the cycle, moves the peak pressure closer to the end of the power stroke, reducing the effective pressure on the piston and thus lowering torque and horsepower. While retarding timing can help prevent knock or protect the engine under high boost or aggressive conditions, it generally decreases power. So the statement is not correct.