This paper discusses in detail three applications of photoelasticity to engine component design and failure analysis. This stress analysis technique provides whole field stress distribution and can also be used to optimize a design by obtaining even stress distribution. The applications discussed cover several aspects of photoelasticity such as two and three dimensional model analysis, stress freezing, thermal and mechanical loading simulation. These are some of the many investigations conducted by the authors and can be used as a guide to many other applications. The results of the analysis have been verified during endurance testing, but are not discussed in this paper.