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In this study, biodiesel is produced from waste sunflower oil and its ef-fect on engine performance and specific fuel consumption is experimen-tally investigated. Transesterification method was used in biodiesel pro-duction of waste sunflower oil. After production, analyzes giving charac-teristics of biodiesel such as density, kinematic viscosity, sulfur and water content were made. As a result of the analysis, the biodiesel fuel with a viscosity of 4,372 mm2/s, which has a reaction temperature of 60°C, an alcohol content of 25% and a catalyst ratio of 0.05%, was cho-sen as a reference fuel, as it was observed to comply with European Standards of EN 14214. Standard diesel fuel was taken as reference for the purpose of examining the effect of biodiesel on engine performance. Performance and fuel consumption tests of the produced biodiesel and standard diesel fuel were carried out at the full load position at seven dif-ferent engine speed levels. Experiments were carried out on a single cy-linder four-stroke Cussons P8160 engine. As a result of the test, it was observed that there was a 7.06% reduction in engine moment compared to the standard diesel fuel use of B100 fuel. In addition, compared to the standard diesel fuel of B100 fuel, there was a 6.64% reduction in engine power. Specific fuel consumption values for B100 and diesel fuels at 2200 rpm engine speed were 426.75 g/kWh and 355.22 g/kWh, respecti-vely.

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In this study, a dynamic model of a single-cylinder four-stroke diesel engine has been created, and the crankshaft speed fluctuations have been simulated and validated. The dynamic model of the engine consists of the motion equations of the piston, conrod, and crankshaft. Conrod motion was modeled by two translational and one angular motion equations, by considering the kinetic energy resulted from the mass moment of inertia and conrod mass. Motion equations involve in-cylinder gas pressure forces, hydrodynamic and dry friction, mass inertia moments of moving parts, starter moment, and external load moment. The In-cylinder pressure profile used in the model was obtained experimentally to increase the accuracy of the model. Pressure profiles were expressed mathematically using the Fourier series. The motion equations were solved by using the Taylor series method. The solution of the mathematical model was performed by coding in the MATLAB interface. Cyclic speed fluctuations obtained from the model were compared with experimental results and found compitable. A validated model was used to analyze the effects of in-cylinder pressure, mass moment of inertia of crankshaft and connecting rod, friction, and piston mass. In experiments for 1500, 1800, 2400, and 2700 rpm engine speeds, crankshaft speed fluctuations were observed as 12.84%, 8.04%, 5.02%, and 4.44%, respectively. In simulations performed for the same speeds, crankshaft speed fluctuations were calculated as 10.45%, 7.56%, 4.49%, and 3.65%. Besides, it was observed that the speed fluctuations decreased as the average crankshaft speed value increased. In the simulation for 157.07, 188.49, 219.91, 251.32, and 282.74 rad/s crankshaft speeds, crankshaft speed fluctuations occurred at rates of 10.45%, 7.56%, 5.84%, 4.49%, and 3.65%, respectively. The effective engine power was achieved as 5.25 kW at an average crankshaft angular speed of 219.91 rad/s. The power of friction loss in the engine was determined as 0.68 kW.

In this study; brake discs used in vehicles have investigated. The behavior of these discs during braking, wear and braking distance performance of the coated and uncoated surfaces during the braking process were evaluated. The surface of the commercially produced discs was coated with a thickness of 1 mm using the HVOF (High Velocity Oxy-Fuel) coating method. In the coating process CoNiCrAlY, WC-Co (88/12), NiCrBSi and MoNiCrBSiFe (Mo 25%) 4 (four) different ceramic powders were used respectively. Wear and brake distance tests of coated and uncoated discs were performed by braking in a total of 20 brakes in 15 seconds on the brake-suspension tester. After the brake tests, the surface roughness changes of the discs, surface hardness change, mass loss and the abrasion values on the disc surfaces were determined due to the brake force applied to the discs during the experiment. The most wear on the discs was on the CoNiCrAlY ceramic powder coated disc at 0,4 g, while the least wear occurred on the disc coated with NiCrBSi ceramic powder at 0,2 g.