Adding dome-shaped protuberances, or polydomes, to an engine system increases the structural integrity of the engine component to which they are added and allows noise radiated in the engine system to be reduced in certain regions of the frequency spectrum without incurring a significant increase in the mass of the engine part to which they are added, which may result in a longer solidification time during the mold injection process. The size and spatial arrangement of polydomes relative to one another can be further adjusted to reduce noise within the engine system and polydomes may be reinforced with ribs to increase the structural stiffness of plastic engine components. Because plastic engine components are created using an injection mold process during the manufacturing process, added surface features (e.g. polydomes and ribs) are continuous with the underlying planar surface to which they are added.

Intake sound reduction device for internal combustion engine includes an elastic member formed into substantially cylindrical shape and having an open base end, a top end sealed by an end surface wall and a bellows circumferential wall; a base plate retaining base end of elastic member; and a communication pipe whose one end is connected to base plate so that a volume chamber formed inside elastic member communicates with an intake passage of the engine. Intake sound reduction device has first resonance system formed by expansion and contraction in axial direction of elastic member and second resonance system formed by film-vibration of end surface wall. When either one of resonance frequencies of the first and second resonance systems is primary resonance frequency and the other is secondary resonance frequency, the primary resonance frequency is set to 30200 Hz and the secondary resonance frequency is set to 50300 Hz.

An intake manifold is provided. That intake manifold includes a body having at least one runner and an impact stress concentrator projecting outwardly from the at least one runner.

An intercooler pipe that improves noise, vibration, and harshness (NVH) performance is provided. The intercooler pipe includes a plurality of bellowses, wherein an exterior of the bellows is made of a soft material and an inside thereof is made of a hard material to make a storage modulus of the inside of the bellows greater than that of the exterior thereof. In addition, the intercooler pipe improves the durability of an intercooler pipe.

An intercooler pipe for a vehicle may include an inlet which is positioned at an upper portion of the intercooler pipe; an upper bellows portion which forms an upper bellows body that protrudes in a rib shape from a surface of a pipe body extended in a direction toward the inlet; an outlet which is positioned at a lower portion of the intercooler pipe; a lower bellows portion which forms a lower bellows body that protrudes in a rib shape from a surface of the pipe body extended in a direction toward the outlet; and an intermediate portion which has the pipe body bent downward from the upper bellows portion and connected to the lower bellows portion, wherein a thickness of the pipe body of the intermediate portion is greater than a thickness of the upper bellows body and a thickness of the lower bellows body.