$29 piston and crankshaft 3D model by iucc92. Available on CGTrader with 23125 polys and 24035 vertices. Geometry: Polygon mesh. Check it out on CGHub.
C4D (Cinema 4D, filesize: 3.84 MB), FBX (Autodesk FBX, filesize: 4.1 MB), MAX (Autodesk 3ds Max, filesize: 4.14 MB), FBM (fbm, filesize: 4.14 MB)