There is something called COCOMO that was developed and used almost 30 years ago to estimate time although it may not be applicable exactly to your work. However, its approach of taking into account many various technical (e.g., estimated number of modules or lines of code) and human (e.g., number of developers on the team that are skilled and familiar with the technologies) factors is going in the right direction. But not matter what estimates are produced, management will browbeat the time downward and the development team almost always work like hell to meet the deadline.