The knocking tendency in spark ignition engines may be decreased by

A. Controlling the air-fuel mixture

B. Controlling the ignition timing

C. Controlling the exhaust temperature

D. Reducing the compression ratio

Answer: Option D

Solution(By Examveda Team)

The knocking tendency in spark ignition engines may be decreased by Reducing the compression ratio. -A lean mixture reduced the knocking tendency, allowing to operate the CFR engine at higher CCR. -The high concentration of nitrogen in the mixture increased the ignition delay time of the end gas, thus reducing the knocking tendency of the engine.