what makes I-section to have more strength and lighter in weight? in engines where this considerations are use

Answer 1

Stress flows down the outside of parts I beams have been around a long time by removing material from the middle the part gets lighter and the edges where the strength has to be can take the stress. Material Science 101. Best example is the connecting rods, resistance to compression strong in torsion and new engine construction using main bearing frame work based loosely on I beam design.