Today, the necessity for a vehicle with lower emissions and consumption, is more urgent than ever. While CNG fuel is a solution for emission concerns, using CNG in conventional engines cause some technical problems, reducing power and torque. Designing a CNG-based engine to overcome this problem is a drastic solution, especially in Iran. Because Iran has the second most abundant gas reserves worldwide, the Iranian government has requested that automakers design a CNG-based engine. IPCO, the largest engine research and development company in Iran, is a pioneer in CNG-based engine design. IPCO implements modern technology to develop the EF7 engine, which strives to find a balanced solution to the challenging demands of performance, cost, and environmental friendliness.
After multi-valve technology became standard in engine design, the challenge shifted to increasing engine output using Variable Valve Timing Technology (CVVT). To optimize breathing, engines require different valve timing at different speeds. When engine speed increases, the duration of intake and exhaust stroke decreases, so that fresh air is not fast enough to enter the combustion chamber, while exhaust gases are not fast enough to leave the combustion chamber. Therefore, the best solution is to open the inlet valves earlier and to close the exhaust valves later. The overlap between intake period and exhaust period should be increased as rev increases.
Engine valve seats, combined with the intake and exhaust valves, serve as seals for high-temperature, high-pressure exhaust gas. Because of this, the valve seat material is required not only to have its own wear and heat resistance, but must also ensure it does not cause adverse wear of the valves with which it works. When CNG, LPG, and other gas fuels were used for combustion in vehicle engines, a large degree of valve seat wear was observed and it was difficult to provide the same wear resistance as for gasoline engines. Therefore, the mechanism of valve seat wear in gas fuel engines was analyzed and an alloy valve seat developed. The machinability of the product represents a manufacturing constraint. In EF7 engine design, IPCO developed valve seat material to solve valve seat wear and effectively to seal the combustion chamber.