Book Description This book is an excellent guide for engineers & designers to accurately estimate KMPL for any given condition before vehicles are actually produced. One can also verify if we make certain design changes exactly how much will be improvement in kmpl.The graph on cover page shows how the KMPL (kms/litre) changes in different gears with increase in vehicle speed. It can be seen that there is wide variation in kmpl depending upon gear in which it is operated & the speed of the vehicle.Once we understand why & how much fuel consumption changes one can find no. of ways to reduce fuel consumption.For better understanding of the subject, it is convenient to express fuel consumption in cc/km (instead of kmpl). Fuel consumption due to various factors can be added together to get total fuel consumption. Total fuel consumption in cc//km can then be expressed in KMPL.Actually, fuel consumption is directly proportional to the energy required to overcome various opposing forces like - rolling resistance α Wair resistance α V2engine frictionIn conventional methods energy requirement is worked out & then fuel consumption is estimated taking into account engine efficiency. But engine efficiency varies to a great extent under different conditions. Particularly part load efficiency of the engine is very low. This wide variation in engine efficiency makes it practically impossible to work out fuel consumption based on energy requirement. That is the reason why you don't find any book explaining variations in fuel consumption under different conditions. This problem of wide variation in engine efficiency has been overcome by introducing the concept of fuel consumption due to engine friction. Once this part of fuel consumption due to engine friction is separated out, the remaining part of fuel consumption is directly proportional to energy requirement. Hence using this method it is very easy to work out fuel consumption from energy requirements. Fuel consumption due to engine friction in cc hr can be directly measured by running the engine with vehicle stationary & measuring fuel consumption with a test pot. But this needs to done by keeping engine r.p.m. constant. The readings may be taken at different engine r.p.m.s As shown above for getting total fuel consumption we need to account for only 3 factors i.e rolling resistance, air resistance & engine friction. In highway running, vehicle speed is high & fuel consumption due air resistance in total fuel consumption can be as high as 75 to 85 %. But in city operation, due to lower vehicle speed & operation in lower gear, fuel consumption due to engine friction is in the range of 45 % to 80 % of total fuel consumption. All the above points are explained in detail in the book. There is a great scope to reduce this consumption. Tricky situations - There are some tricky situations & many people sometimes even government agencies are advocating - " Do not accelerate faster, as it consumes more fuel" But the real fact is that it does not affect your trip kmpl. This point is explained in detail in the book. Various methods to save fuel by improving driving habits are given in detail.Also various points for design improvements for improving kmpl are also given in the book. There are various simple tests that can be carried out by simply driving the vehicle which makes it possible to compare KMPL under two different conditions without any instruments. Many such interesting topics are given in the book.Important thing is that once you get thoroughly acquainted with the subject, you yourself will be able to find out the ways & mea ns to get best KMPL. So, go ahead & best of luck.
