Abstract: An aluminum pipe according to the present invention is used in forming a plurality of bulged portions on the peripheral wall thereof. At the same time by bulging has been so refined as to exhibit an elongation of at least 40% and a recrystallization texture of up to 60 .mu.m in grain size during bulging. The aluminum pipe to be bulged is produced by a process characterized by drawing an extruded aluminum pipe at a cold working ratio of at least 40%, and thereafter annealing the drawn pipe at a temperature of 350.degree. to 420.degree. C., whereby the pipe is refined to exhibit the specified elongation and recrystallization texture.

Abstract: An intake manifold adapted for use with an engine having two intake ports for each cylinder incorporates an aluminum plenum chamber having an air inlet and air outlets twice the number of cylinders of the engine in number, and a plurality of branch pipes of wrought aluminum connected to the respective air outlets of the plenum chamber. One of the two branch pipes to be connected to the intake ports for each cylinder is larger in the length of the channel than the other branch pipe. The two branch pipes are equal in the cross sectional area of the pipe channel, or the branch pipe having the longer channel is smaller than the other branch pipe in the cross sectional area of the channel. The roughness of the inner surface of each branch pipe is up to 10 .mu.m, preferably up to 5 .mu.m, more preferably up to 1 .mu.m, in terms of center line average height.

Abstract: The invention is drawn to an intake manifold for an internal combustion engine. The manifold is made of an aluminum plenum chamber having an air inlet and a plurality of air outlets with a plurality of wrought aluminum branch pipes extending from the respective plenum outlets. The branch pipes have an inner peripheral surface of circular cross section. At least one of the branch pipes is deformed at an intermediate portion along its length thereby forming a clearance area so that the branch pipe is free from contact with the adjacent branch pipe.

Abstract: An intake manifold adapter comprising an adaper body made of aluminum and having a gas channel adapted to communicate at its one end with the outlet of a throttle body for holding an air cleaner in communication with an intake manifold and at the other end thereof with the inlet of the manifold, and an exhaust gas inlet pipe having an aluminum portion at its one end and a stainless steel portion secured thereto and providing the other end of the pipe, the inlet pipe being fixed to the adapter body by the aluminum portion being metallurgically joined to the body, the stainless steel portion providing a joint for a pipe for returning the exhaust gas from an engine to the manifold.

Abstract: A stop-weld composition for forming a corrosion inhibiting layer on the internal surface of aluminium tube in sheet comprises 2.0 to 50.0% of boron nitride, 0.2 to 10.0% of bentonite, 5.0 to 50.0% of finely divided zinc and the balance solvent.