An electrical power generation system, comprising: a first, relatively high pressure compartment (14, 144, 514, 544, 644) having an elevated pressure with respect to an ambient pressure environment including an inlet region and a first outlet region; a second, relatively low pressure compartment (16, 116, 516, 616) having an elevated pressure with respect to the ambient pressure environment including a second outlet region; a bulkhead between the first compartment (14, 144, 514, 544, 644) and the second compartment (16, 116, 516, 616); at least one first fan in the first compartment (14, 144, 514, 544, 644), wherein the at least one first fan draws ambient air into the first compartment (14, 144, 514, 544, 644) through the high pressure inlet region and pressurizes the air in the first compartment (14, 144, 514, 544, 644) to a first pressure that is greater than the ambient pressure; a radiator in the first compartment (14, 144, 514, 544, 644) coupled to the first outlet region, wherein the pressurized air in the first compartment (14, 144, 514, 544, 644) flows out of the first compartment (14, 144, 514, 544, 644) through a first flow path, the first flow path being through the radiator and the first outlet region; an engine in the second compartment (16, 116, 516, 616), the engine coupled to the radiator for cooling, wherein the pressurized air in the first compartment (14, 144, 514, 544, 644) flows from the first compartment (14, 144, 514, 544, 644) through a second flow path, the second flow path being through the bulkhead and into the second compartment (16, 116, 516, 616), wherein the engine is coupled to an alternator at least partially in the first compartment (14, 144, 514, 544, 644) having an air flow path through the alternator included in the second flow path, wherein the alternator air flow path extends through the alternator and the bulkhead and includes an alternator inlet region opening in the first compartment (14, 144, 514, 544, 644) and an alternator outlet region opening in the second compartment (16, 116, 516, 616); and an exhaust aftertreatment system (46, 146, 546, 646) coupled to the engine to clean combustion gases exiting the engine and arranged to be bathed at least in gases exiting the first compartment (14, 144, 514, 544, 644) on the first flow path; wherein the first compartment (14, 144, 514, 544, 644) and the second compartment (16, 116, 516, 616) are horizontally spaced from one another, the radiator (28, 528, 628) is arranged above the alternator in a top portion of the first compartment (14, 144, 514, 544, 644), and the exhaust aftertreatment system (46, 146, 546, 646) is arranged above the second compartment (16, 116, 516, 616). a first, relatively high pressure compartment (14, 144, 514, 544, 644) having an elevated pressure with respect to an ambient pressure environment including an inlet region and a first outlet region; a second, relatively low pressure compartment (16, 116, 516, 616) having an elevated pressure with respect to the ambient pressure environment including a second outlet region; a bulkhead between the first compartment (14, 144, 514, 544, 644) and the second compartment (16, 116, 516, 616); at least one first fan in the first compartment (14, 144, 514, 544, 644), wherein the at least one first fan draws ambient air into the first compartment (14, 144, 514, 544, 644) through the high pressure inlet region and pressurizes the air in the first compartment (14, 144, 514, 544, 644) to a first pressure that is greater than the ambient pressure; a radiator in the first compartment (14, 144, 514, 544, 644) coupled to the first outlet region, wherein the pressurized air in the first compartment (14, 144, 514, 544, 644) flows out of the first compartment (14, 144, 514, 544, 644) through a first flow path, the first flow path being through the radiator and the first outlet region; an engine in the second compartment (16, 116, 516, 616), the engine coupled to the radiator for cooling, wherein the pressurized air in the first compartment (14, 144, 514, 544, 644) flows from the first compartment (14, 144, 514, 544, 644) through a second flow path, the second flow path being through the bulkhead and into the second compartment (16, 116, 516, 616), wherein the engine is coupled to an alternator at least partially in the first compartment (14, 144, 514, 544, 644) having an air flow path through the alternator included in the second flow path, wherein the alternator air flow path extends through the alternator and the bulkhead and includes an alternator inlet region opening in the first compartment (14, 144, 514, 544, 644) and an alternator outlet region opening in the second compartment (16, 116, 516, 616); and an exhaust aftertreatment system (46, 146, 546, 646) coupled to the engine to clean combustion gases exiting the engine and arranged to be bathed at least in gases exiting the first compartment (14, 144, 514, 544, 644) on the first flow path; wherein the first compartment (14, 144, 514, 544, 644) and the second compartment (16, 116, 516, 616) are horizontally spaced from one another, the radiator (28, 528, 628) is arranged above the alternator in a top portion of the first compartment (14, 144, 514, 544, 644), and the exhaust aftertreatment system (46, 146, 546, 646) is arranged above the second compartment (16, 116, 516, 616).