The ornamental design for an engine, as shown and described.
FIG. 1 is a front elevational view of an engine showing our new design;
FIG. 2 is a rear elevational view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a perspective view thereof, taken from the top, front and left side of the engine.
The broken lines are for purpose of illustrating portions of the article that form no part of the claim. The surface is lined for contour only, and no claim is made to a particular texture. No claim is made to portions not shown in the drawings.