Check out dik stirling motor 3D model on CGTrader for $25. High-quality mesh by bubercreative. PBR, Textured.
SLDPRT (SolidWorks, filesize: 575 KB), BLEND (Blender, filesize: 575 KB), FBX (Autodesk FBX, filesize: 575 KB), DWG (AutoCAD, filesize: 575 KB), DXF (DXF, filesize: 575 KB), STP (STEP, filesize: 575 KB)