How the number of engine cylinders affects its mechanical efficiency

The relation between engine principal dimensions, i.e. piston diameter to stroke ratio is the parameter often modified in order to increase engine efficiency and durability. A similar operation is the achievement of given volume for different number of cylinders, which is the subject of the following paper. For recent years the engine manufacturers have been proposing in-line engines of 3, 4, 5 and 6 cylinders more eagerfy than in last century. Obviously engines of lesser cylinder number are proposed for small car s while those of greater number - for most dynamic ones. One can ask a question whether the cylinder number for a certain swept volume affects such parameters as engine efficiency and durability as well as lube oil consumption. There is no simple answer to this ąuestion but simulations performed by the author allow estimating tendencies in changes of those parameters for various numbers of cylinders. Moreover, it is quite vital that engine complex modifications accompanying the change in cylinder number have been taken into consideration in a course of carried out tests. Lesser number of cylinders for the same volume results in more solid pistons and connecting rods, worse engine run irregularity and soon. The paper presents introductory conclusions which allow selecting an engine of the cylinder number that ensures the best economical and dynamical parameters for a given car.