The influence of the exhaust system on power output and fuel consumption is shown for blower scavenged 2 stroke cycle diesel engines with loop scavenging and symmetrical timing diagrams. Basic laws of wave propagation and wave superimposition are treated and relationships for the points of discontinuity are stated. The influence of the natural frequency of the exhaust system is pointed out, and formulas for its determination are given. Exhaust pulse charging and the Kadenacy effect are briefly discussed. Experimental results are reported for various designs of exhaust systems for 1, 2, 3, and 4 cyl engines, and the determinative results are discussed.