Exhaust silencer for your car

Super-silent driving at full performance with the end silencer

The end silencer is the technical component at the end of an exhaust system. It causes the noise development of an engine to be as limited as possible. An intact end silencer guarantees quiet driving, a good thing for the driver and the environment.

Engines are louder than you think

If you wonder how loud an engine actually is, try removing the flex pipe. The infernal noise even a small 1-litre 40 HP engine can generate is amazing. Loud enough for you to better choose a remote area for this experiment to prevent annoying your neighbours. The cause lies in the engine's operation: a mix of fuel and air is vaporised and ignited with a spark. The resulting explosion presses the piston deep into the engine, driving the crankshaft and all other moving parts of the engine. An average engine runs at 1000 – 5000 rpm. Depending on size of the engine, this is 2 – 4 explosions per revolution – which makes 20.000 explosions per minute. If this noise would be released into the environment unfiltered, you wouldn't be able to understand a single word.

Simple principle, cheap spare part

The end silencer converts noise into mechanical waves. In a technical sense, the end silencer is very simple: it is a tin can with two pipes attached. The pipes sit across at an angle and partly overlap. The exhaust gas together with the sound – nothing else but compressed air – flows into the can on one side. The gas can flow backwards to reach the other pipe. From there it escapes into the environment. The sound on the other hand, cannot flow backwards. The motion energy of the compressed air causes the metal pot to vibrate – and that is all. The vibrations are absorbed by the long, sturdy rubbers of the exhaust suspension. Nothing of it reaches the bodywork.

Costs for an end silencer

Car manufacturers have the choice: either they develop exhaust systems lasting an entire car's life span, or they build this highly stressed module as a wear part. The high-grade alternative can only be made of stainless steel. Due to the high material prices and the sophisticated processing, standard installation of a stainless steel end silencer would make a car almost £1000 more expensive. Therefore, most cars have an end silencer of simple metal. These are available at 30 EUR (c. £27).

Wear of an end silencer

The end silencer is always under high stress, constantly suffering strong temperature changes. Furthermore, the exhaust gases react extremely aggressive when they mix with water. The penetration of water in the end silencer cannot practically be avoided: the colder the air, the more moisture a cooling end silencer attracts. This explains why an exhaust always exhales white fumes on winter mornings. Especially in winter the end silencer is up to threefold stress: strong fluctuations between hot and cold, external erosion by road salt and internal attacks by a mix of soot and water, causing the end silencer to rust gradually.

Defects of the end silencer

A defective end silencer cannot be ignored: the car becomes increasingly louder. As end silencers are made of thin metal for reasons of weight, repair welding is generally not worthwhile. Plating pieces welded onto the corroded metal of the end silencer do not hold for long. You only postpone the defect for several days, before the end silencer breaks down again. A replacement is considerably simpler, cheaper and more durable.