Crank angle leads directly to piston location and displacement. Combustion chamber volume can be calculated from displacement and compression ratio CR=(displacement+combustion chamber volume)/(combustion chamber volume). You need to know the stroke, rod length, bore, and compression ratio. The calculations can be done in Excel. The formulas and a picture can be found at https://en.wikipedia.org/wiki/Piston_motion_equations

Dudley J Benton Thanks for your good answer Dear Dr Dudley J Benton . I'm really thankful for that ....

Hi. You can use the internal combustion engine books (by Dr. Ramos or Ferguson). I will be sending this book to you as soon as possible.

All the formulas you are looking for are listed in the preliminary chapters of these books.

You need to write these formulas in MATLAB software and then import your P & theta file.

Mehrdad Nazemian So you say that in Ferguson's book i can find the exact relations for this ? what about Heywood ? you now i am a little confused because these relations are the easiest among those we use in IC Engines and also easy to forget and mostly we didn't pay enough attention to them as we work on the other thermodynamic relations and etc

Thanks for your helpful answer my dear friend

The equation is available in Heywood too (section 2.2: Geometrical properties of reciprocating engines). The relationship of V and theta can also be found in books on Mechanisms of Machinery because the piston-conrod-crank system is a slider crank mechanism.

It can be easily calculated through the relation of cylinder volume as a function of crank angle degree.