Engine coolant system and method

A coolant system for an engine, comprising:

• a coolant feed gallery coupled inside an engine crankcase;
• a coolant return gallery coupled inside the engine crankcase;
• a first cooling unit including a cylinder liner jacket surrounding a first cylinder, an upper coolant jacket and a lower coolant jacket surrounding a head of the first cylinder, and an exhaust port cooling jacket coupled to an exhaust port of the first cylinder;
• a second cooling unit including another cylinder liner jacket surrounding a second cylinder, another upper coolant jacket and another lower coolant jacket surrounding a head of the second cylinder, and another exhaust port cooling jacket coupled to an exhaust port of the second cylinder, wherein each of the first and the second cooling unit is coupled to the coolant feed gallery and the coolant return gallery;
• a pump coupled to the coolant feed gallery for pumping coolant from the coolant feed gallery into each of the first cooling unit and the second cooling unit;
• and
• one or more proportioning valves coupled downstream of the pump and upstream of each of a first coolant feed line for the first cooling unit and a second coolant feed line upstream of the second cooling unit, the one or more proportioning valves having at least a first position and second position wherein changing positions of the one or more proportioning valves varies a ratio for coolant flow directed to the first coolant feed line relative to the coolant feed line.

A method for cooling an engine, comprising:

• flowing coolant, drawn from a feed gallery coupled to a crankcase, through a first cooling unit encasing a first cylinder block and an associated cylinder head;
• concurrently flowing coolant, drawn from the feed gallery coupled to the crankcase, through a second cooling unit encasing a second cylinder block and an associated cylinder head, wherein the first and second cylinder blocks are positioned adjacent to each other, the first and second cylinder blocks coupled to the crankcase;
• varying a first ratio of coolant flowing through the first cooling unit relative to the second cooling unit based on individual cylinder operating conditions;
• and
• varying the first ratio includes increasing the first ratio of coolant flowing through the first cooling unit relative to the second cooling unit, via a proportioning valve, as a cylinder head temperature of the first cylinder block exceeds the cylinder head temperature of the second cylinder block.