A dynamometer test of a six-cylinder Otto four-stroke cycle engine with a 231 in3 displacement gave the following results at 4000. rpm:
- Indicated power output = 250: hp
- Actual ðor brakeÞ power output = 75:0 hp
- Heating value of the fuel being used = 20:0 × 103 Btu/lbm
- Fuel consumption rate = 54:0 lbm/h
Determine
a. The mechanical efficiency ηm of the engine.
b. The ASC thermal efficiency of the engine.
c. The isentropic compression ratio (CR) of the engine, assuming an Otto cold ASC.
d. The mean effective pressure (mep) inside the combustion chamber