A rough guess for non turbo diesel peak pressure is in the 1100 to 1300 psi range near TDC. Perhaps if you have an IMEP in mind someone can give you a better estimate.
The real pressure rise, over compression pressure, begins when fuel begins to burn, just a bit after injection.
Advancing the injection timing beyond some optimum will raise the cylinder pressure but power output will not increase much because the negative work required to bring the piston up to TDC offsets the gain on the down stroke. (You just put more strain on the components of the engine).
The speed at which the fuel burns (cetane rating) and the speed with which it can be injected are critical to good performance. (These factors actually limit the top speed of a diesel engine).
The electronic control of injectors and emissions requirements have changed the game in the last decade. (Later injection and lower peak pressures help to reduce NOx). Some strategies squirt a small charge into the combustion chamber before TDC to get an ignition source going, and then dump the main charge in later. I have heard (but not seen) that some have tried three different injection points in a cycle. I have only witnessed dual charge cycles. (This can lead to two pressure peaks in some cases)!
Such custom injection timings were not possible with the old pump-line-nozzle systems.
For an analysis of several types of diesels you might start with the March 1943 Journal of Applied Mechanics for Fredrick Porter’s article on the Harmonic Coefficients of Engine Torque Curves. His curves do not extend beyond 150 psi MEP for 4 cycle diesels but you can get a good idea of what the curve for a higher pressure will look like.
You could ask an injector manufacturer (Bosch, Siemans ?) for a typical pressure curve.
