Exhaust System: Description and Operation

RA4900KE30010X 0010 - Function Description: Exhaust System KE-Injection

49-0010 Exhaust system

The exhaust system passes the exhaust combustion gases, with the lowest possible backpressure, to the tail of the vehicle where they flow into the atmosphere with a low noise level.

The exhaust system consists of:
^ Front exhaust system with catalytic converter or with front muffler (vehicles without KAT).
^ Center muffler
^ Rear muffler with tail pipe.

The front exhaust pipe is designed as a single or twin-pipe system. In some cases, the pipes are merged. Pre-catalytic converters or resonators may be welded in place in the front exhaust pipe.

The cross-section of the exhaust pipes or twin pipes, pipe routing, location of pipe merging point, muffler design, muffler volume and total weight of the exhaust system are matched to the engine.

Parts of the exhaust system are designed to be double-walled and with an additional insulating layer in order to reduce the heat dissipation and to provide for noise insulation.

Shields reduce heat dissipation to the floor.

The exhaust system is suspended by means of rubber elements and a side support to the transmission. Noises in the passenger compartment as a result of mechanical vibration of the exhaust system are thus reduced.

If the exhaust system upstream of the oxygen sensor is leaking, the oxygen content in the exhaust gas rises. The lambda control enriches the mixture (increased fuel consumption).





Noise insulation of the exhaust gases is performed by the inner design of the mufflers. A distinction is made between reflection and absorption dampers. Both types may be combined in a muffler.

Reflection dampers consist of several chambers. Perforations (also slots) connect the chambers. The noise of the exhaust gases is dampened by means of bends, cross-section steps, branching filters, reflection orifices, Venturi nozzles etc.

Absorption dampers are packed with sound absorbing wool. The sound waves penetrate out of the exhaust gas-conducting inner pipe through the openings into the sound-absorbing wool where they are damped.

A Reflection muffler
B Reflection/absorption muffler
C Absorption muffler
1 Perforations
2 Sound-absorbing wool
3 Branching filter
4 Reflection orifice
5 Venturi nozzle

The parts of the exhaust system are welded or bolted with flange and socket connections.

In the standard version the rear muffler on a number of models is welded to the exhaust system. In order to replace the rear muffler, the exhaust pipe is sawn apart and a socket connection fitted.





Flanged connection of exhaust pipes

2 Front exhaust pipe
3 Self-locking nut
5 Sintered seal
5a Flange
5b Graphite seal
7 Center exhaust pipe
8 M8 bolt





Flanged connection to exhaust manifold

1 Rivet nut
1a Exhaust manifold
2 Front exhaust pipe (tulip version)
2a Flange
4 Bolt





Example of exhaust system, model 126

A Engine 117 RuF Twin-pipe version
B Engine 116 RuF Pipes merged with cross pipe behind engine
7 Two center mufflers
9 Rear muffler with two tail pipes