I think you put up a very similar question before and Dr. Abdallah Daddi Moussa Ider gave a brief answer to it. It depends on what you want to resolve. If you want a heat release rate curve of a diesel engine you actually are running and testing, I should say it is not possible to obtain one. Many parameters influence heat release rate curves. For example, in actual diesel engines even if you maintain the amount of fuel per cycle, by doing so-called "timing swing (varying fuel injection timing)" heat release rate curves change significantly, therefore, knowing only engine specifications and amount of fuel per cycle is grossly lacking in necessary information to obtain an actual heat release rate curve. Now, if what you want to know is a heat release rate curve of the Diesel cycle described in text books, which is defined as a constant pressure heat release during the expansion stroke, you do not have to worry about fueling. The heat release rate is proportional to the geometrical volume expansion rate if you ignore details such as the increase in total mass in the cylinder. In the same line of argument the heat release rate of the Otto cycle is infinite, although the amount of released heat is finite.