Abstract: An engine part has a construction which prevents the surface discoloration/deterioration associated with a high-temperature exhaust gas, irrespective of the type of Cr used in the formation of a chromium plating layer (hexavalent chromium or trivalent chromium). The engine part includes a metal substrate, a chromium plating layer covering at least a region of a surface of the metal substrate, the region being heated to a temperature of about 350° C. or more, and an intermediate plating layer provided between the metal substrate and the chromium plating layer. The chromium plating layer has a thickness of about 0.2 ?m or more in the region.

Abstract: A system includes a combustion engine for a genset. The engine having an exhaust to emit water and exhaust gases from the exhaust and a sound-dampening device coupled between the exhaust and a muffler, the sound-dampening device including a tubular member having internal rings.

Abstract: A muffler includes a case divided into three chambers by two baffles. The first chamber is closest to, and the third chamber is farthest from, the exhaust pipe. An inlet pipe has a first end connected to the exhaust pipe, and a second end in fluid communication with the third chamber. An outlet pipe expels exhaust and water from the first chamber to the exterior. A connecting pipe provides fluid communication between the first and third chambers. The second end of the inlet pipe is above the bottom interior surface of the outlet pipe. The inlet pipe may have holes in the second chamber, above the bottom interior surface of the outlet pipe. The connecting pipe may have holes in the second chamber. The baffles may have holes for the water to flow from the second and third chambers to the first chamber. Also, an exhaust apparatus utilizing the muffler.

Abstract: It's an object of the present invention to provide a black smoke exhaust purification apparatus capable of equalizing temperature of a particulate filter and facilitating maintenance thereof. The black smoke exhaust purification apparatus (20) is arranged in series therein with an oxidation catalyst (4) and a particulate filter (1), wherein an inlet for exhaust gas (10) is disposed between the oxidation catalyst (4) and the particulate filter (1), and wherein an exhaust gas passage is extended from the inlet portion through the oxidation catalyst (4) so as to be connected to an upstream space (2a) of the oxidation catalyst (4).

Abstract: A rotatable sound attenuation device is provided comprising a central portion rotatable about a first axis, a radial portion extending outwardly from the central portion and a chamber having a closed first end and a second end opening radially outwardly of the radial portion and defining a second axis therein having a radial component thereto. A piston is disposed within the chamber and is moveable to a location along the second axis in response to a centrifugal force imparted on the piston by rotation of the central portion and the radial portion about the first axis. A biasing member operates to limit movement of the piston along the second axis. A quarter wave chamber is defined by the second, open end of the chamber and the piston and has a sound attenuating length defined by the location of the piston along the second axis of the chamber.

Abstract: An exhaust system for a motorcycle includes a muffler configured for attachment at a location substantially beneath a motorcycle engine. The muffler includes a first input port and a second input port. A first exhaust pipe has a first longitudinal length. The first exhaust pipe is configured for extending between and connecting the first input port and a first exhaust port of a first motorcycle engine cylinder while being substantially entirely disposed forwardly of a motorcycle engine. A second exhaust pipe has a second longitudinal length substantially equal to the first longitudinal length. The second exhaust pipe is configured for extending between and connecting the second input port and a second exhaust port of a second motorcycle engine cylinder. A motorcycle including an exhaust system is also provided.

Abstract: An exhaust system for an engine includes a first muffler having a housing, a first end plate, a second end plate, an inlet pipe extending through at least one of the first end plate and the second end plate, and an outlet pipe extending through at least one of the first end plate and the second end plate. The exhaust system further includes a second muffler having a housing, a first end plate, a second end plate, an inlet pipe extending through at least one of the first end plate and the second end plate, and an outlet pipe extending through at least one of the first end plate and the second end plate. The exhaust system further includes a crossbreed pipe extending through the first end plate of the first muffler and the first end plate of the second muffler.

Abstract: An arrangement for controlling exhaust pressure pulsation in a combustion engine including six cylinders. The engine also includes an inlet for supply of air to the cylinders, and an exhaust manifold for delivery of exhaust gases from the cylinders. The manifold is provided with a first outlet to an exhaust system and with a second outlet to a conduit for feeding exhaust gases back, via an EGR circuit, from at least one of the engine's cylinders to the inlet. At least one of the cylinders is adapted to enrich the exhaust gases with unburnt hydrocarbon with a view to regeneration of an exhaust gas post-treatment unit situated in the exhaust system. A special configuration of the exhaust manifold results in separation of regeneration gas from EGR gas in the exhaust manifold.

Abstract: In order to make available an exhaust gas system for a combustion engine with an external housing, which contains at least one rear shell and one front shell, and with a catalyst chamber, in which at least one catalyst element is arranged, and with an exhaust gas duct, from which exhaust gas is conveyed from the catalyst chamber, said exhaust gas system including few components and being able to be produced cost-effectively and wherein harmful thermal stresses in the components of the exhaust gas system are largely avoided, the catalyst chamber also forms the exhaust gas duct. The catalyst chamber has at least two chamber halves, and the exhaust gas duct is provided materially uniform and in one piece in at least one chamber half.

Abstract: An exhaust system for an internal combustion engine includes a catalytic device within an exhaust path of the engine, wherein the catalytic device includes a housing with a catalyst carrier. A length of the catalyst carrier along a longitudinal axis, measured along a downstream flow direction of exhaust gas within the exhaust path, is substantially the same or a shorter than the upstream distance traveled by a reverse flow of exhaust gas during an exhaust gas pulsation within the housing. With this type of configuration, due to reciprocating movements of the exhaust gas caused by the pulsations, the same exhaust gas passes through the catalyst carrier multiple times. Thus, an increased number of heat exchanges take place within the catalyst carrier, which rapidly increases the catalyst temperature after a cold engine start.

Abstract: The present invention relates to a mixing element and an exhaust system of an internal combustion engine. The mixing element has two inlet openings and two outlet openings, wherein each inlet opening communicates with both outlet openings.

Abstract: A pulse attenuator for the EGR line of an internal combustion engine in which a main flow path has a pair of branch flow paths extending from the upstream portion of a venturi. The branch flow paths have a precisely determined length so as to reintroduce pulses back to the main flow path in a way that smoothes the flow. The pulses may be reconnected to the main flow path downstream of the point at which they are extracted or at the same point. The length of the branch passages may be different to provide attenuation of pulses at different engine rpms.

Abstract: An exhaust system of an internal combustion engine having at least one cylinder comprises a main exhaust passage connected to the cylinder; a main catalytic converter disposed in the main exhaust passage; a bypass exhaust passage that diverges from the main exhaust passage, the bypass exhaust passage having a gas flow resistance larger than that of the main exhaust passage and having a downstream end connected to the main exhaust passage at a position upstream of the main catalytic converter; an auxiliary catalytic converter disposed in the bypass exhaust passage; and a gas flow switching device that is capable of forcing exhaust gas from the cylinder of the engine to flow toward the bypass exhaust passage when assuming a given operation position.

Abstract: An exhaust system for an internal combustion engine having a plurality of cylinders is disclosed. The exhaust system comprises a plurality of exhaust branch passages, an intermediate exhaust pipe section, a partition plate and a downstream pipe section. Each exhaust branch passage is in communication with a respective cylinder. The intermediate exhaust pipe section forms a passage that is in communication with the exhaust branch passages. The partition plate is provided in the intermediate passage and divides the intermediate passage into first and second flow paths. The partition plate further includes a projection positioned on a first surface thereof that is oriented so as to be generally perpendicular to the direction of exhaust flow. The partition plate is disposed within the intermediate passage so as to position the projection in the first flow path.

Abstract: A gas flow enhancer for a combustion engine includes a housing, configured to receive an inlet flow of gas at an inlet pressure, and enclosing an expansion chamber. Disposed within the expansion chamber are a set of inner vanes and outer vanes, and a flow separator. The outer vanes are disposed outside the flow separator and produce an outer helical flow of the gas. The inner vanes are disposed within the flow separator and produce an inner helical flow of the gas, the inner helical flow having a higher velocity and lower pressure than the outer helical flow. The outer helical flow and inner helical flow are recombined at an outlet of the expansion chamber so as to produce an outlet laminar flow profile having a lower average pressure than the inlet pressure.

Abstract: An exhaust gas purifying apparatus is provided for a motorcycle, configured to minimize engine output characteristics, and to raise the temperature of a catalyst to an activation temperature rapidly after a start of the engine, while not increasing a vehicle body size. The motorcycle includes an engine in which a cylinder block is extended upward on a crankcase. An exhaust port is provided on a front portion of the engine; an exhaust pipe extends forward of the engine from the exhaust port, then extends downward once, and thereafter, extends toward the rear of a vehicle body. A catalyst is placed in the exhaust pipe. The exhaust pipe passes along a side of the cylinder block, and the catalyst is placed in the exhaust pipe in a position located on the side of the cylinder block.

Abstract: Unobstructed, pressurized air from the forward movement of a vehicle such as a pickup, SUV or automobile is forced into an air scoop (mounted to the undercarriage of the vehicle). This air is then channeled through a section of exhaust pipe (having the fewest possible bends) parallel (with an approximate 4? separation) along the muffler to the end of the tailpipe. A section of exhaust pipe (“crossover pipe”) is welded to the tailpipe outward at an acute angle which is then welded at an obtuse angle to the pressurized air pipe with both pipes being welded open to each other. As the pressurized air passes the crossover pipe, a vacuum is created in the crossover pipe pulling gases out of the tailpipe and then pushing them out of the pressurized air pipe, with this process reducing backpressure in the exhaust system and improving fuel economy.

Abstract: A device for generating an acoustic signal in a fluid includes an engine operable to repeat a thermodynamic process to vibrate a membrane of the engine to generate an acoustic signal having more than one period. The thermodynamic process includes heating mass inside a chamber of an engine to generate pressure inside the chamber; in response to generating the pressure, moving in a first direction a portion of a membrane of the engine; removing mass from inside the chamber to decrease the pressure inside the chamber; and in response to decreasing the pressure inside the chamber, moving the membrane portion in a second direction. Because the engine repeats the thermodynamic process, the engine can generate and sustain an acoustic signal for a significant amount of time.

Abstract: A four-cycle engine is provided that includes an exhaust port for releasing combusted gas from the engine and an exhaust system. The exhaust system includes an exhaust pipe coupled with the exhaust port, a first catalyst, a second catalyst, and a secondary air introduction pipe. The first catalyst is disposed in the exhaust pipe and the second catalyst is disposed in the exhaust pipe a set distance downstream of the first catalyst. The secondary air introduction pipe is configured to introduce air into the exhaust pipe. The secondary air induction pipe is connected to the exhaust pipe between the first and the second catalysts at a location where a temperature difference of the first and the second catalysts in a cold start transient phase is within a predetermined range.

Abstract: An exhaust-carrying component (2) of an exhaust system (1) for an internal combustion engine is provided, in particular for a motor vehicle. The component (2) includes a pipe (4) through which exhaust gas can flow from one longitudinal end (6) to the other longitudinal end (7) and which has between its longitudinal ends (6, 7) a longitudinal section (8), the wall (9) of which is provided with perforations (10). The component (2) also has a housing (5) which surrounds the pipe (4) in a circumferential direction and to which the pipe (4) is fixedly connected in both one end area (11) having a longitudinal end (6) and in another end area (12) having the other longitudinal end (7). In order for the component (2) to nevertheless be able to resist the thermal stresses that occur during operation, the perforations (10) are designed so that the longitudinal section (8) can absorb thermal longitudinal expansion forces between the pipe (4) and the housing (5) through elastic deformation.

Abstract: A muffler for an exhaust gas system of an internal-combustion engine has an exhaust gas inlet and a first flow pipe arranged inside the muffler and completely penetrating the muffler. A shut-off device is arranged in the first flow pipe, for the shutting-off and opening-up an exhaust gas tail pipe which is situated downstream of the muffler and is connected with the first flow pipe. A second flow pipe partially penetrates the muffler, and has an overflow path between the first and second flow pipes situated inside the muffler. The first and the second flow pipes are connected with the exhaust gas inlet by way of a branching element and the shut-off device is arranged upstream of the muffler in the first flow pipe.

Abstract: The object of the invention is to customize the properties of the drive assembly of motor vehicles comprising an intake system, an exhaust system, and/or an internal combustion engine. For this purpose, the mechanical properties of a serial drive assembly, the engine parameters efficiency and rotational torque, and the acoustics of the serial intake and/or exhaust system are stored in a database in an initial step. Furthermore, the construction features of the serial drive assembly that can be customized are stored in the database with their variation parameters and limitations. After varying at least one construction feature, the modifications of the engine parameters resulting therefrom are calculated and stored as a parameter difference. Likewise, the resulting changes of the acoustic features are calculated and stored as sound difference. Thereafter, the original values of the serial drive assembly are overwritten with the difference values and reproduced acoustically.

Abstract: An InfraRed Suppression System (IRSS) vectors engine exhaust flow away from the exhaust manifold plane, the high aspect ratio exhaust duct defined as a ratio of a maximum nozzle length to a maximum nozzle width, the ratio greater than 2:1.

Abstract: An arrangement for controlling exhaust pressure pulsation in a combustion engine including six cylinders. The engine also includes an inlet for supply of air to the cylinders, and an exhaust manifold for delivery of exhaust gases from the cylinders. The manifold is provided with a first outlet to an exhaust system and with a second outlet to a conduit for feeding exhaust gases back, via an EGR circuit, from at least one of the engine's cylinders to the inlet. At least one of the cylinders is adapted to enrich the exhaust gases with unburnt hydrocarbon with a view to regeneration of an exhaust gas post-treatment unit situated in the exhaust system. A special configuration of the exhaust manifold results in separation of regeneration gas from EGR gas in the exhaust manifold.

Abstract: An exhaust system of an engine of a motorcycle, including an exhaust pipe configured to extend in one of an upward direction and a downward direction from an exhaust port formed at a front portion of a cylinder head of the engine and to then be bent to extend in an opposite direction to form a bent portion at a location in front of the engine.

Abstract: A vertical exhaust water trap assembly has an outer housing and an internal housing or exhaust tube defining an annular water collection spaced therebetween bypassing a central exhaust flow area.

Abstract: An exhaust system for a vehicle includes a muffler including end walls and a side wall connected to the end walls enclosing an interior space of the muffler. A first pipe is disposed within the interior space of the muffler and extends from one end of the muffler at which exhaust gas enters the muffler. A catalyst is located in the first pipe and at least one additional pipe is disposed within the interior space such that a longitudinal axis of the at least one additional pipe is spaced from a longitudinal axis of the first pipe in a direction that is substantially perpendicular to the longitudinal axis of the first pipe. The first pipe includes a plurality of holes disposed in a sidewall thereof at an upstream side of the catalyst in a direction in which exhaust gas passes through the muffler. The holes in the first pipe are arranged such that some of the exhaust gas passes through the catalyst and the remainder of the exhaust gas passes through the plurality of holes so as to bypass the catalyst.

Abstract: The present invention provides a method of operating a dynamic exhaust system of a motorcycle engine. The method includes providing a valve in the exhaust system that is movable to direct exhaust gases between a first flow path through the exhaust system and a second flow path through the exhaust system. The method includes actuating the valve at a first speed to redirect exhaust gases from the first flow path to the second flow path and actuating the valve at a second speed greater than the first speed to redirect exhaust gases from the second flow path to the first flow path.

Abstract: A catalytic converter-incorporated exhaust system is provided, which includes an exhaust tube through which exhaust gases emitted from an engine flow, and a muffler fluidly connected with a downstream end of the exhaust tube. This muffler includes a muffler casing having a plurality of expansion chambers defined therein, an exhaust introducing passage for introducing the exhaust gases from the exhaust tube into the expansion chambers in succession, two catalytic converters mounted in an downstream portion of the exhaust introducing passage and operable to substantially purify the exhaust gases, and an exhaust composition detecting sensor disposed outside the muffler casing in the exhaust introducing passage.

Abstract: The invention concerns an internal combustion engine exhaust line comprising an active noise reduction system with variable choke device, continuously regulated based on the instantaneous discharge rate pulses of exhaust gases exiting from the internal combustion engine, including an expansion chamber for closing phases of the variable choke device arranged upstream of said active noise reduction system and a cavity dispersing medium and high frequencies arranged downstream of the active noise reduction system. The expansion chamber for the closing phases of the variable choke device is integrated in a first depolluting system arranged upstream of said active noise reduction system.

Abstract: Exhaust passage control valve 10 may comprise housing 30, valve member 20, and helical torsion spring 40. Housing 30 has an exhaust passage. Exhaust gas from an internal combustion engine flows through the exhaust passage of the housing 30. Valve member 20 opens and closes the exhaust passage of the housing. Helical torsion spring 40 may be disposed at the opposite side of the valve member from the housing side thereof. Helical torsion spring 40 comprises a coil part wherein spring wires have been wound in a coil shape, and arms formed at both ends of the coil part. The coil part may be disposed at approximately the center of the valve member. When the arms bend with respect to the coil part, the counter-force of this bending energizes the valve member towards a closing side. The spring mounting member may be arranged and constructed to adjust a position in which the spring mounting member is mounted on the housing such that a rotation angle of the arms can be changed.

Abstract: A method for cleaning a filter having Z-media includes providing a filter having Z-media and cleaning the media construction by directing a pulse of compressed gas into the media construction through the downstream flow face. Filter elements useable with such methods include elements made of Z-media. An example system utilizing the method includes a gas turbine air intake system.

Abstract: The object of the invention is to customize the properties of the drive assembly of motor vehicles comprising an intake system, an exhaust system, and/or an internal combustion engine. For this purpose, the mechanical properties of a serial drive assembly, the engine parameters efficiency and rotational torque, and the acoustics of the serial intake and/or exhaust system are stored in a database in an initial step. Furthermore, the construction features of the serial drive assembly that can be customized are stored in the database with their variation parameters and limitations. After varying at least one construction feature, the modifications of the engine parameters resulting therefrom are calculated and stored as a parameter difference. Likewise, the resulting changes of the acoustic features are calculated and stored as sound difference. Thereafter, the original values of the serial drive assembly are overwritten with the difference values and reproduced acoustically.

Abstract: Sound and power are an important part of the motorcycling experience. From the early days people have been attempting to get it “right” and have tried numerous ways to achieve the best of both worlds. Generally one had to be sacrificed to some degree to get the other. Tuning the exhaust rather than tuning the carburetor or increasing cubic inches is a less expensive and more efficient way to get both the sound and midrange power that motorcyclists are looking for. With the exhaust enhancement device of the present invention, exhaust pipes can be tuned for sound and increased midrange power very simply and easily by installing them in the exit end of an aftermarket straight type pipe using various combinations to achieve a desired sound and not sacrifice power.

Abstract: The subject invention refers to a muffler comprising a muffler housing (1, 2) and generally a catalytic converter element (13) mounted in the housing, which muffler has at least one inner outlet (4) through which exhaust gases cleaned by the catalytic element (13) are intended to pass. Furthermore, according to the invention an outlet duct (30, 31) is arranged in connection to the outside of the housing, comprising a first section (30) for leading exhaust gases in a first direction (A) in parallel with the outside of the housing, and a second section (31) for leading exhaust gases in a second, opposite direction (B), whereby said first and second sections (30, 31) have an essentially equally large cross-sectional area. By way of this outlet duct an improved cooling of the exhaust gases before they are brought in contact with fresh air rich in oxygen can be achieved. A back-pulsation of fresh air into the muffler can also be prevented.

Abstract: An exhaust system for a multi-cylinder engine can include a plurality of exhaust pipes with first upstream ends connected to exhaust openings of a multi-cylinder engine, and a collecting pipe connected to the second downstream ends of the exhaust pipes for collecting exhaust introduced from the exhaust pipes and directing it to a silencer. The collecting pipe has a front-end portion communicated to exhaust passages of the exhaust pipes, a middle portion for collecting the exhaust introduced from the front-end portion, and a rear-end portion for further collecting the exhaust introduced from the middle portion. The middle portion is provided with exhaust control means for controlling the area of the exhaust passages in accordance with engine speed.

Abstract: An exhaust system for an internal combustion engine having a first cylinder and a second cylinder from which pulses of exhaust gas exit and are routed along separate paths towards the exhaust mufflers. The exhaust system independently routes the pulses of exhaust gas from the two cylinders. The exhaust gases that are expelled from the first cylinder are routed through a first exhaust pipe. The exhaust gases that are expelled from the second cylinder are routed through a second exhaust pipe assembly. The second exhaust pipe assembly routes the exhaust gasses from an exhaust port for the second cylinder laterally across the motorcycle to achieve a true dual exhaust system. The second exhaust pipe assembly provides an approximate equal length flow path as compared to the path used by the exhaust gasses that are expelled from the first cylinder.

Abstract: A two cycle internal combustion engine cylinder having a piston chamber. The cylinder includes transfer ports; and an exhaust port divided into at least two sections. A first one of the sections has an aperture at the piston chamber with a top surface located closer to a top of the piston chamber than a top surface of an aperture of a second one of the sections at the piston chamber. The first section has a cross-sectional area which is smaller than a cross-sectional area of the second section. The aperture into the first section is located further away from the transfer ports than the aperture into the second section.

Abstract: An exhaust water trap assembly has separated and spaced exhaust tubes, and a dome cap blocking entry of water to protect an upstream catalytic converter or soot filter. A first tube extends axially upwardly into a housing, and a second tube is spaced vertically thereabove. The dome cap on the top end of the first tube blocks exhaust flow axially upwardly therepast and blocks entry of water axially downwardly therepast.

Abstract: A system for attenuating exhaust noise from an engine with a first group of active cylinders and a second group of deactivatable cylinders includes a first exhaust manifold connected to the first group of active cylinders and a second exhaust manifold connected to the second group of deactivatable cylinders. The second exhaust manifold is connected to the first exhaust manifold such that the second exhaust manifold acts as a resonator to attenuate sound from the first group of active cylinders when the second group of cylinders is deactivated.

Abstract: An assembly useful in reducing aircraft engine noise such as turbofan engine noise (730) comprises: (i) at least one tube “H-Q” having an inlet end (738), an outlet end (740) and a central tube portion therebetween; and (ii) at least one actuator operatively interconnected to at least one tube, wherein the actuator is capable of causing dynamic response by the tube. The assembly of this invention may be used in a method for reducing noise, the method comprising: (a) providing means for generating non-uniform noise energy about an inner surface and within a disclosure having at least an inlet; (b) providing an assembly for reducing noise comprising; (i) at least one having an inlet end, an outlet end and a central tube portion therebetween, and (ii) at least one actuator operatively interconnected to at least one tube, wherein the actuator is capable of causing dynamic response by the tube; and (c) directing at least a portion of the non-uniform noise into the assembly.

Abstract: Exhaust system assemblies employ wire bushings for thermal compensation to minimize noise due to “stick-slip” while the system cools. In a preferred embodiment, the wire bushings are formed of at least one strand of wire coiled about male end portions of pipe sections used in the system, each of which male end portions are inserted into a female end portion and held therein by an interference fit. The strand of wire is spot welded at spaced locations to the male end portions to provide bearing surfaces between the spot welds that move slightly as the exhaust system heats and cools to relieve thermal stress in small, substantially inaudible increments.

Abstract: A motorcycle exhaust control system for covering exhaust cross-over pipes is comprised of an elongate tubular crossover block-off member having a side wall. The crossover block-off member side wall has a slit extending the length thereof. The crossover block-off member forms the springed structure capable of placement in a motorcycle exhaust pipe. The crossover block-off member is capable of self-detainment in the motorcycle exhaust pipe. The crossover block-off member is capable of blocking the motorcycle exhaust pipe crossover.

Abstract: An exhaust system for a dual crankshaft engine system having a first engine and a second engine having a common exhaust member open at an end thereof for venting engine exhaust. A first exhaust member is adapted to be coupled to the first engine and coupled to the common exhaust member. The first exhaust member has a first catalytic converter formed thereon. A second exhaust member is adapted to be coupled to the first engine and coupled to the common exhaust member and has a second catalytic converter formed thereon. A third exhaust member is adapted to be coupled to the second engine and coupled to the common exhaust member. A fourth exhaust member is adapted to be coupled to the second exhaust engine and coupled to the common exhaust member. A third catalytic converter is provided in the exhaust member.

Abstract: A combination exhaust gas post treatment/muffler device in the exhaust gas section of an internal combustion engine is provided. A special platinum-coated preliminary oxidation catalytic converter is combined with at least one particle separator, which is exactly coordinated therewith, in a muffler to achieve carbon particle separation rates of greater than 50%.

Abstract: A induction exhaust system, for an internal combustion engine, capable of the multi step processes of 1) scavenging the chamber of exhaust gases and free radicals, 2) breaking the scavenge vacuum wave behind each energetic exhaust pulse, releasing said free radicals and the overscavenged air fuel vacuumed from the intake manifold during valve overlap, and 3) induction of such free radicals, unburned fuel, and fresh matter including atmospheric air.

Abstract: In an exhaust manifold of a four-cylinder engine four cylinders of which line up in order of cylinder #1, cylinder #2, cylinder #3 and cylinder #4, temperature rise performance of a manifold catalyst improves by shortening a total length of the exhaust manifold while preventing exhaust gas interference between the cylinders. Therefore, an exhaust manifold branch of cylinder #1 and an exhaust manifold branch of cylinder #4 in outward sides of the engine that are not fired in succession are made convergent with its convergence angle ?1 being equal to or below 20 degrees to form a first convergent exhaust manifold branch and an exhaust manifold branch of cylinder #2 and an exhaust manifold branch of cylinder #3 between the cylinder #1 and cylinder #4 that are not fired in succession are made convergent at a minimum distance having a laterally projected shape to form a second convergent exhaust manifold branch.

Abstract: A muffler assembly for an internal combustion engine of a portable handheld work apparatus such as a motor-driven chain saw, cutoff machine or the like includes an exhaust-gas muffler (1) which has a muffler housing (10). The muffler housing (10) is formed essentially from two half shells (24, 25) connected substantially fluid-tight to each other. The interior space of the muffler housing (10) includes at least two chambers (2, 3) which are partitioned from each other by a partition wall (4). A catalytic converter (5) is mounted in the partition wall (4). In the interior space of the muffler housing (10), an exhaust-gas inlet (6) opens which is connected to an exhaust-gas stub (9) of the cylinder (8) of the engine. The exhaust-gas muffler has an exhaust-gas outlet (7) which conducts exhaust gas from the interior space.

Abstract: An exhaust muffler system for use on a motorcycle or four-wheeled vehicle provides for operation in either of two modes, a regular configuration that provides a high degree of noise reduction, or a racing specification that provides for a freer-flowing exhaust. Without changing the main body of the muffler, an operator can choose between a quieter, public road setting or a louder, high performance setting. The muffler is provided with two interchangeable spark arresters, and a main body having multiple expansion chambers therein, defined by bulkheads. When a regular spark arrester is installed, exhaust gas passes through one bulkhead three times, greatly reducing the noise produced. With the spark arrester removed, the exhaust gas passes straight through to the open air, enhancing performance. A seal is provided between the bulkheads and the spark arrester, which provides for extension or retraction in the lengthwise direction of the tail pipe.

Abstract: An exhaust processor comprises a Helmholtz resonance chamber with a variable tuning throat. The tuning frequency of the exhaust processor changes as the outlet opening from the variable tuning throat into the Helmholtz resonance chamber changes.