This paper investigates the effect of semi thermal barrier coating (TBC) onTorodial (re-entrant) piston bowl geometry combustion chamber at a higher compression ratio of 19.5:1 in an internal combustion engine. The tests were performed on a single cylinder, four stroke, direct injection, diesel engine using E50 ethanol diesel blend. The engine’s piston crown was coated with variousTBC materials in different composition ratios such as Aluminium oxide (Al2O3) + Molybdenum (Mo) + Titanium oxide(TiO2) (40%+30%+30%), over a 150μm thickness of NiCrAlY bond coat. The maximum thickness of coating is about 300 μm.The engine with and without coating has been tested with the test fuels and diesel fuel in the same operating conditions.The test resultshows that they coated engine has areduction in brake specific fuel consumption (BSFC) and an increase in brake thermal efficiency (BTE) of about 6%. It is also observed that there is a considerable increase in NOx of about 4.32 % and reduction in CO and HC emission. The analyses of the results were carried out using scanning electron microscope (SEM) and EDX.