Engine and engine work machine

An engine, comprising:

• a cylinder, which is connected to a crankcase and forms a combustion chamber;
• and a muffler, which is secured to the cylinder;
• wherein the muffler comprises:
• an outer housing and an inner housing, which form an external wall of an expansion chamber;
• and a partitioning plate, which separates the expansion chamber into a first expansion chamber on an inner housing side and a second expansion chamber on an outer housing side;
• and the muffler is a substantial box shape formed by joining the outer housing and the inner housing with the partitioning plate;
• seen from an axis direction of the cylinder, the partitioning plate is disposed with a slope so that a distance from the partitioning plate to the cylinder decrease as the partitioning plate gets away from the crankcase;
• the outer housing comprises an upper wall surface, and
• an exhaust outlet is disposed on a cylinder side of the upper wall surface and discharges an exhaust gas toward a counter-cylinder side along a wall surface of the muffler.