Sankar Palchoudhury 101/673/A, College Para, P.O. Kharia, Ward No. 21, Dist. Jalpaiguri, Pin Code -735101, West Bengal, IndiaCMOH Office, Jalpaiguri, Government of West Bengal, India sankarpalchoudhury@gmail.comcmoh_jal@wbhealth.gov.in International Journal of Fundamental Physical Sciences (IJFPS) 9 1 10-13 March, 2019 2231-8186 https://doi.org/10.14331/ijfps.2019.330123 This paper presents the Palchoudhury Gas Theory and its application to heat engine dynamics. It describes two distinct methods to quantify the capacity of a heat engine using pressure and surface area, and a thermodynamic expression involving gas constants, temperature, and molecular surface area. The study provides detailed equations and tables showcasing force variations and thermodynamic transformations during compression and expansion cycles. Experimental results are demonstrated using CO₂ and other gases. The findings highlight how force discharge relates to changes in surface area and temperature, offering a new perspective on internal gas dynamics in heat engines. Heat Engine, Thermodynamics https://creativecommons.org/licenses/by-nc/4.0/