An internal combustion engine comprising: at least two opposed cylinders (100, 200; 1100, 1200), each comprising one pair of opposed pistons (110, 120, 210, 220; 1110, 1120, 1210, 1220) reciprocating along a common axis, and an end of each opposed piston (110, 120, 210, 220; 1110, 1120, 1210, 1220), in conjunction with a cylinder (100, 200; 1100, 1200), defining a combustion chamber (150, 250; 1150, 1250); and a crankshaft (300; 1300) having at least one journal coupled to at least one pullrod (411, 421; 1411, 1421) and at least one pushrod (412, 422; 1412, 1422) for a pair of opposed pistons (110, 120, 210, 220; 1110, 1120, 1210, 1220), a scavenge pump associated with each cylinder (100, 200; 1100, 1200), the scavenge pump comprising a first scavenging chamber (105, 205; 1105, 1205) and a second scavenging chamber (109, 209; 1109, 1209), the first scavenging chamber (105, 205; 1105, 1205) defined by an end of a housing and a plunger (118, 218; 1118, 1218) linked to one of the opposed pistons distal from the crankshaft (300; 1300), wherein the plunger (118, 218; 1118, 1218) is adapted to move in unison with the piston and to draw in a fluid from outside the housing to the first scavenging chamber (105, 205; 1105, 1205), the second scavenging chamber (109, 209; 1109, 1209) adapted to expel fluid into the combustion chamber (150, 250; 1150, 1250), characterized in that the second scavenging chamber (109, 209; 1109, 1209) is defined by a cylinder cavity (104, 204; 1104, 1204), the plunger (118, 218; 1118, 1218) and a cylinder liner (130, 230; 1130, 1230), and in that the plunger (118, 218; 1118, 1218) is adapted to expel fluid from the first scavenging chamber (105, 205; 1105, 1205) to the second scavenging chamber (109, 209; 1109, 1209). at least two opposed cylinders (100, 200; 1100, 1200), each comprising one pair of opposed pistons (110, 120, 210, 220; 1110, 1120, 1210, 1220) reciprocating along a common axis, and an end of each opposed piston (110, 120, 210, 220; 1110, 1120, 1210, 1220), in conjunction with a cylinder (100, 200; 1100, 1200), defining a combustion chamber (150, 250; 1150, 1250); and a crankshaft (300; 1300) having at least one journal coupled to at least one pullrod (411, 421; 1411, 1421) and at least one pushrod (412, 422; 1412, 1422) for a pair of opposed pistons (110, 120, 210, 220; 1110, 1120, 1210, 1220), a scavenge pump associated with each cylinder (100, 200; 1100, 1200), the scavenge pump comprising a first scavenging chamber (105, 205; 1105, 1205) and a second scavenging chamber (109, 209; 1109, 1209), the first scavenging chamber (105, 205; 1105, 1205) defined by an end of a housing and a plunger (118, 218; 1118, 1218) linked to one of the opposed pistons distal from the crankshaft (300; 1300), wherein the plunger (118, 218; 1118, 1218) is adapted to move in unison with the piston and to draw in a fluid from outside the housing to the first scavenging chamber (105, 205; 1105, 1205), the second scavenging chamber (109, 209; 1109, 1209) adapted to expel fluid into the combustion chamber (150, 250; 1150, 1250), characterized in that the second scavenging chamber (109, 209; 1109, 1209) is defined by a cylinder cavity (104, 204; 1104, 1204), the plunger (118, 218; 1118, 1218) and a cylinder liner (130, 230; 1130, 1230), and in that the plunger (118, 218; 1118, 1218) is adapted to expel fluid from the first scavenging chamber (105, 205; 1105, 1205) to the second scavenging chamber (109, 209; 1109, 1209).