Question 98Motor Plants - Assistant Engineer

The correct answer is C) turbulence of the air charge. The rate of pressure rise during the period following fuel ignition in a diesel engine is influenced by the length of the ignition delay period and the turbulence of the air charge. The turbulence of the air charge affects the mixing of the fuel and air, which in turn influences the rate of combustion and the rate of pressure rise. Increased turbulence leads to better fuel-air mixing, resulting in a faster rate of pressure rise. The other options, such as valve overlap (A), volumetric efficiency (B), and fuel efficiency (D), do not directly affect the rate of pressure rise in the same way as the turbulence of the air charge.