Figures 15-23 and 15-10 show the variation in brake specific fuel consumption (bsfc) for a swirl-chamber ID1 automobile diesel (D) and a conventional automobile spark-ignition (SI) engine as a...

Figures 15-23 and 15-10 show the variation in brake specific fuel consumption (bsfc) for a swirl-chamber ID1 automobile diesel (D) and a conventional automobile spark-ignition (SI) engine as a function of load and speed, respectively. From these graphs determine, and then plot, brake fuel conversion efficiency: (1) as a function of speed at full load and (2) as a function of load at a mid-speed of 2500 revjmin. Both engines are naturally aspirated. Assume the engine details are:

(a) List the major engine design and operating variables that determine brake fuel conversion efficiency.

(b) Explain briefly the reasons for the shapes of the curves you have plotted and the relative relationship of the D and SI curves.

(c) At 2500 revjmin, estimate which engine will give the higher maximum brake power.