Internal combustion engine

The internal combustion engines used in the vehicles are based on two principles:

•  spark ignition ( petrol engines ) principle

•  Diesel principle.

The key features of the ICs based spark ignition principle are:

•  high power/weight ratio

•  good performance

•  low combustion noise.

The disadvantages of are the ICs based spark ignition principle are:

•  quality of fuel required

•  higher fuel consumption.

The advantages of the diesel engines are:

•  low fuel consumption

•  low maintenance requirement due to absence of ignition system

•  low fuel quality required

The disadvantages of the diesel engine are

•  high level of particulate emission

•  greater weight and higher price

•  higher levels of noise

The two typical characteristic curves used to describe the engine characteristic are:

•  torque vs. engine speed curve at full load (100% acceleration pedal position)

•  power vs. engine speed curve at full load (100% acceleration pedal position)

These two characteristic curves are shown in Figure 4. In Figure 4 the following nomenclature is used: