A single-cylinder four-stroke oil engine at full load gave: indicator diagram area 300 mm², length 40 mm, spring scale 1 bar/mm; speed 400 rpm; brake load 400 N; spring-balance reading 50 N; brake-drum diameter 1.2 m (neglect rope thickness); fuel consumption 3 kg/h; calorific value 42 000 kJ/kg; cylinder diameter 160 mm; stroke 200 mm. Find (a) the indicated power (kW), (b) the brake power (kW), (c) the mechanical efficiency (%) and (d) the brake thermal efficiency (%).