Determination of Optimum Valve Opening and Height in the Automotive Engine

The effects of the valve opening and opening height are very crucial in internal combustion engine. The optimum setup for the opening cam high and timing of camshafts in engines will improve fuel economy and exhaust gas emission. This improvement can be obtained from intake (inlet) valve timing and also from exhaust (outlet) valve timing. The challenging technique is to set up the engine to the optimum valve opening and closing for inlet and outlet in the combustion engine and to synchronize the timing of valves under range of speeds of the engine. The objective of this paper is to determine the optimum setup of engine cams to increase the efficiency. A small engine with one piston has been used to find the best valve opening and closing by replacing cams and then drawing graphs of loads for five different camshafts. The best points that give the highest load for the engine in a rage of speeds will be indicated after drawing the graphs. At the low engine speed, it was found the engine requires high breathing to give high efficiency and then required low breathing to get the best load among the designed camshafts and then earlier breathing. It was found also the improvement reached to 15% increase in load from the original setup after decreasing the inlet cam height by 3 mm at certain point of speed. The result highlights the importance of designing a flexible camshaft that can change its cam size and angle at the same time during engine operation to give more efficiency to engines.