Finally the volumetric efficiency was found to be 60%. It is important to point out that the torque of the engine is dependent on the speed at which the engine turns and it is normally expressed in revolutions per minute (rpm).
The curve of the power torque graph for the polo engine slopes smoothly and increases steadily as the revolutions per minute increase. The relationship of torque versus the engine is non linear. This relationship is provided as curve as shown on the torque curve. The exact shape and the height of the curve is specific for each engine type and this is normally determined by engine tests. The curve peaks at approximately 4000 rpm with a torque of about 90.3 N/M. The curves can be defined within the range of 1100-5500 rpm since that is the operating range of the polo engine. If the range is made lower than this, the engine is likely to stall while an increase would damage the engine.
For energy balance to occur within the internal combustion engine, it is important that the total power generated by the brake power is kept at its peak. Energy performance is an indication of the degree at which the success of the internal combustion polo engine performs its assigned task. The total power is normally developed by the combustion of the fuel in the combustion chamber is greater than the brake power usually referred to as indicated power. This can be calculated as:
The balance of the energy in the internal combustion engine will indicate that approximately 1/3 of the fuel energy that has been input is normally lost to the external environment through transfer of heat. There is also another 1/3 is available as the shaft performs its work. The heat losses must be decreased in order to improve the efficiency of the engine.
3. Exhaust smoke and other emissions: The oxides of nitrogen and any unburned carbons are an indication of the rate of efficiency of the engine. This parameter can be used