Method of adjusting capacities of combustion chambers of a multi-cylinder engine

A method of adjusting capacities of combustion chambers of a multi-cylinder engine having a cylinder head with recessed parts that partially form the combustion chambers and a mating surface for mating with a cylinder block, the method comprising:

• casting a cylinder head material having flat reference surfaces on top of the recessed parts of the cylinder head;
• machining the cylinder head material to form the mating surface;
• measuring distances in a height direction from the mating surface to the reference surfaces, respectively;
• and
• adjusting machining margins of machining portions of the reference surfaces of the recessed parts based on the measured height direction distances;
• wherein the casting the cylinder head material includes forming the machining portions of the recessed parts to have a predetermined machining margin with respect to a target combustion chamber capacity;
• and
• wherein the multi-cylinder engine has a compression ratio of 12:1 or higher.

A method of adjusting capacities of combustion chambers of a multi-cylinder engine having a cylinder head with recessed parts that partially form the combustion chambers and a mating surface for mating with a cylinder block, the method comprising:

• casting a cylinder head material having flat reference surfaces on top of the recessed parts of the cylinder head;
• machining the cylinder head material to form the mating surface;
• measuring distances in a height direction from the mating surface to the reference surfaces, respectively;
• and
• adjusting machining margins of machining portions of the reference surfaces of the recessed parts based on the measured height direction distances;
• wherein the combustion chamber is a pent-roof combustion chamber having an intake port side inclined surface and an exhaust port side inclined surface;
• wherein the reference surface is provided at a boundary between the intake port side inclined surface and the exhaust port side inclined surface;
• wherein the adjusting the machining margins includes machining an opening edge portion of the recessed part over an area from an intake port to an exhaust port based on the measured height direction distance, the opening edge portion serving as the machining portions;
• wherein the casting the cylinder head material includes forming the machining portions of the recessed parts to have a predetermined machining margin with respect to a target combustion chamber capacity;
• wherein the adjusting the machining margins includes setting the machining margins smaller when the measured height direction distance is larger than a reference height direction distance and setting the machining margins larger when the measured height direction distance is smaller than the reference height direction distance;
• and
• wherein the multi-cylinder engine has a compression ratio of 12:1 or higher.