Aluminium intake manifolds can become dirty and dull after just a short time of use. Polishing an intake manifold makes it easier to keep it clean because, after polishing, the manifold is smoother, giving it an easier-to-clean surface. A polished aluminium intake manifold also brightens up the engine bay around the engine. Polishing an aluminium intake manifold to a mirror finish will take at least one hour to complete. It requires only a drill and some materials from your local auto parts store.
Sand the intake manifold with 180-grit sandpaper to remove all dirt and grit, and to smooth the surface. Make sure to sand all crevices and indentations on the intake manifold. Once it has been sanded with 180-grit sandpaper, sand over the manifold again using 400-grit sandpaper.
Use the 600-grit sandpaper on the intake manifold, but keep this sandpaper wet with water while sanding. This keeps the sandpaper free from build-up that can scratch the aluminium surface. Use water while sanding the manifold then with 1200-grit sandpaper. Rinse the manifold and allow it to dry completely.
Place the buffing pad on the drill. Pour aluminium polish onto the manifold and use the drill and buffing pad to apply the polish. Add more polish as needed. Buff the manifold until the finish is as shiny as you would like.