Combustion processes and emissions attributes squarely depend on combustion vestibule volume shapes relative to injector jet directions and cone angles. For injectors with more number of holes, these parameters change and may result in enhanced performance. By this we can make the gases to flow in different patterns compared to conventional engine and can anticipate higher brake thermal efficiency (BTE) and reduced emanations to meet stringent norms. Hence to optimize combustion chamber shapes (CCS) and vary squish, appropriate injection strategies are essential. In this occasion lab probes were conducted on a single cylinder four stroke open or induction swirl diesel engine using corn oil methyl ester (CROME) as fuel. For this variety of CCS were designed and manufactured. Injector with 6 numbers of hole and 0.2 mm orifice size was used to check its effects on the biodiesel powered engine. The suitable engine available was having Hemispherical Bowl Piston (HBP). To probe the effects of other CCS on the performance of diesel engine, Cylindrical Bowl Piston (CBP), Toroidal Bowl Piston (TBP) and Toroidal Re-entrant Bowl Piston (RBP) vestibule volume shapes were manufactured keeping ratio of compression same. For 100% replacement of diesel by biodiesel the injection pressures and injection timings tested were in the range of 210 bar to 250 bar and 19°bTDC to 27°bTDC which are based on our previous research works on other biodiesels. But the performance was maximised for 240 bar and 27°bTDC for all CCS which is reported in this paper. Engine variables such as fuel flow rate, brake power, torque, and temperature of exhaust smoke, combustion variables such as rate of heat release (HRR), peak pressure (PP), ignition delay (ID), combustion duration (CD), and exhaust emissions such as smoke opacity, HC, CO, and NOx, were measured. Results obtained with RBP shape and for CROME with 6 number of hole injector concluded in overall ameliorated competence with lesser emission levels of CO, HC and smoke, but NOx was almost same as that of diesel. Also reduced ID, CD and increased PP resulted in decreased burning time loss (BTL) increasing competence. Hence this research work shows that the CROME is also compatible and capable of replacing diesel in a diesel engine efficiently.