Turbosmart - 38.1mm Turbo MountTurbosmart 38. 1mm Turbo Mount Billet Turbosmart Turbo Oil Drain Mounting Bracket. It is made from high quality 4130 chromoly steel, which provides exceptional weldability and strength. These turbo oil drain mounts allow fabricators to add an additional layer of mechanical bracing and support to a Turbosmart Turbocharger. Available in 38. 1mm turbo oil drain bolt spacing 50. 8mm turbo oil drain bolt spacing