Intake port structure in an internal combustion engine

摘要

In an intake port structure in an internal combustion engine, an edge portion is formed on a lower surface of an intake port at a location immediately upstream of an intake bore 7. The angle theta formed by the center line L of the intake port with respect to a deck surface is set smaller than the angle theta formed by an exhaust valve seat provided in a pent roof of a combustion chamber with respect to the deck surface. Further, if the height of an apex of the pent roof of the combustion chamber is represented by H0, and an intersection between an extension of the center line L of the intake port 5 and a straight vertical line L0 passing through the apex of the pent roof of the combustion chamber to intersect the deck surface at a right angle is represented by P, the height H of the intersection P is set so that a relation, H0>H>2H0/3 is satisfied.