Internal combustion engine with improved coolant flow distribution

A cooling system for an internal combustion engine comprising:

• a plurality of cylinder jackets formed by an engine block, the plurality of cylinder jackets surrounding respective cylinders and arranged in fluid communication in series such that coolant flows sequentially from a first cylinder jacket through each subsequent cylinder jacket;
• a plurality of discrete lower cylinder head jackets formed by a cylinder head;
• and
• a plurality of passages in fluid communication with the plurality of cylinder jackets and the plurality of lower cylinder head jackets, wherein the plurality of passages from each of the plurality of cylinder jackets that are in direct fluid communication with a corresponding one of the plurality of lower cylinder head jackets in a one-to-one correspondence, wherein a diameter of each of the plurality of passages in fluid communication with one of the plurality of cylinder jackets differ from diameters of the plurality of passages in fluid communication with others of the plurality of cylinder jackets, and wherein the diameters of the plurality of passages in fluid communication with others of the plurality of cylinder jackets are smaller than the diameter of each of the plurality of passages in fluid communication with one of the plurality of cylinder jackets.

A method of metering coolant within between an engine block and a cylinder head of an internal combustion engine, the method comprising:

• passing the coolant through an inlet of the engine block to into a first of a plurality of cylinder jackets formed by the engine block, wherein the plurality of cylinder jackets surround respective cylinders;
• passing the coolant in series from the first of the plurality of cylinder jackets to others of the plurality of cylinder jackets such that coolant flows sequentially from the first of the plurality of cylinder jackets through each subsequent one of the plurality of cylinder jackets;
• passing the coolant from the plurality of cylinder jackets to a plurality of lower cylinder head jackets formed by the cylinder head, wherein one or more passages from each of the plurality of cylinder jackets are in direct fluid communication with a corresponding one of the plurality of lower cylinder head jackets in a one-to-one correspondence, wherein the passing the coolant from one of the plurality of cylinder jackets to one of the plurality of lower cylinder head jackets is through the one or more passages having a larger diameter than the passing the coolant through the one or more passages from all others of the plurality of cylinder jackets to all others of the plurality of lower cylinder head jackets;
• and
• passing the coolant from an outlet of the cylinder head.