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At Mitsubishi Motors, a thin-walled exhaust manifold, made of stainless cast-steel, has been developed with the aim of achieving higher heat-resisting reliability as well as weight reduction. The new exhaust manifold is made of ferritic stainless cast-steel, employing an advanced vacuum casting (CLAS). Its geometry was designed using finite element analysis and its durability was confirmed by testing both on various test devices and on a vehicle. The exhaust manifolds has been adopted on a production engine model and has proven the following advantages over a conventional cast-iron ones; excellent heat resistance. weight reduction of over 20%. possible exhaust emission reduction as a result of lower heat-capacity of the exhaust manifold.

This paper presents several methods for reducing engine weight primarily through substitution with light-weight materials. The efficiency and performance of the engine were reviewed using a light-weight experimental engine (hereinafter called “weight-reduced engine”) constructed by the authors in order to investigate the possibility of practical use of the proposed weight reduction measures. The weight-reduced engine is based on an in-line 4-cylinder, 2.0 liter, gasoline engine with the base engine weight of 162 kg excluding engine oil and coolant and was reduced by 37 kg by applying alternative light-weight materiaLs and new manufacturing techniques. This corresponds to 23 % weight reduction. The materials used in the weight-reduced engine are 53 % steel, 33 % aluminum, 7 % plastics and 7 % other light-weight materials. It was found that by application of light-weight materials, the engine performance of the weight-reduced engine could be improved.

This paper presents current applications and the required considerations of Shot Peening on aluminium alloy castings, case-hardened parts and austempered ductile cast iron. Aluminium alloy castings can be improved of fatigue strength by the effect of compressive residual stress of Shot Peening. As for case-hardened parts, querched martensite in the case-hardened layer is transformed into tempered martensite and retained austenite, first into quenched martensite and then tempered martensite by plastic strain resulted. from Shot Peening. Also, it is noted that this behavior is closely related with the peening intensity, which increases the compressive residual stress and results in increased fatigue strength. In case of austempered ductile cast-iron gear, it will have increased fatigue strength at the teeth root comparable to that of case-hardened gear by the compressive residual stress generated from Shot Peening.