A configuration for a uniflow-scavenged, opposed-piston engine reduces exhaust cross-talk caused by mass flow between cylinders resulting from one cylinder having an open exhaust port during scavenging and/or charging while an adjacent cylinder is undergoing blowdown. Some configurations include a wall or other barrier feature between cylinders that are adjacent to each other and fire one after the other. Additionally, or alternatively, some engine configurations include cylinders with intake and exhaust ports sized so that there is an overlap in crank angle of two or more cylinders having open exhaust ports of about 65 crank angle degrees or less.