In this study, surfaces of combustion chamber parts (cylinder head and piston) were coated with the new generation TBC (thermal barrier coating). Lanthanum Zirconate (La2Zr2O7) based ceramic top layers which have rare element additions such as Yb, Dy and Nd (in the compound of La-1.4(Yb, Nd, Dy)(0.6)Zr2O7) had been successfully produced via APS (Atmospheric plasma spray) method in a double layered design using CYSZ (ceria-yttria stabilized zirconia) as the second material (ceramic interlayer). A single cylinder diesel engine was used at different speeds (1200, 1400, 1600, 1800 and 2000 rpm) and full load for tests. The results of the reference engine were experimentally compared to the results of four different La2Zr2O7 based coatings. The effects of coatings such as torque, specific fuel consumption, exhaust temperature, cylinder pressure, heat release rate, mass fraction burned and pressure increase rates were investigated on the engine. According to the test results, in-cylinder pressure, heat release rate, pressure increase rate, torque and exhaust temperatures increased owing to La2Zr2O7 based coatings. Maximum cylinder pressure, heat release rate and torque values were reached with Yb doped La2Zr2O7 coatings. Combustion occurred later and longer in the whole coated engines. Break specific fuel consumption was achieved %1.26 to 2.6% lower than the reference (uncoated) engine.