ABSTRACT

Spark ignition (SI) engine-powered vehicles play a vital role in passenger transportation, which includes two-, three-and four-wheelers. In the SI engine, the ignition is initiated by an external aid (spark plug). People prefer SI engine-powered vehicles because they have a lower initial cost than CI engine-based vehicles. The SI engine operates with a lower compression ratio (CR: 6 to 11) than the CI engine (CR: 15:1 to 22:1), which leads to a lowering of the weight and complexity of the system, resulting in a reduced vehicle cost. The fuel economy of an SI engine-powered vehicle is on the lower side as compared to a CI engine-powered vehicle due to its reduced compression ratio. Hence, SI engine-powered vehicles are used for mass transportation over only short distances as compared to CI engine-powered vehicles. The details of passenger and mass transportation such as classification, vehicle type, maximum average distance travel, maximum number of hours of operation/day and reasons are given in Table 5.1. The values in the table are approximate and are only given for a better understanding of the topic. The values may change from passenger to passenger and goods to goods.