The exhaust system market is dominated by a limited number of international players, including Tenneco Automotive, ArvinMeritor, Faurecia and Bosal. Increasingly, these companies have to operate on a global scale. There are still a few small manufacturers in existence, but as range proliferation continues these smaller operations are faced with the decision to sell out or disappear altogether. This article is based on some of the market research included in a just published just-auto report.

Although the vehicle makers are pushing platforms, exhaust suppliers must take account of the sheer variety of engines and variation between left and right-hand drive, which requires a lot of modification in exhaust systems. While some suppliers have introduced modularity in a bid to standardise the core parts (thereby reducing cost), others may struggle. These smaller manufacturers are also facing pressure from their customers to invest in sequencing facilities close to the vehicle assembly lines as well as more design capabilities and testing facilities. This, of course, requires massive capital spending. They must be globally competitive, environmentally responsible and offer longer warranties. It is questionable as to how long they can remain independent.

In December 2002, ArvinMeritor acquired the 51% interest in Germany’s Zeuna Starker that it did not already own. Going forward, and as the exhaust becomes more integrated into the engine management and powertrain, another trend is the need for exhaust suppliers to have strong engine system partners, such as Bosch, Siemens VDO and Delphi.

Dr. Herman Weltens, Tenneco Automotive’s vice president of engineering and technology, believes the replacement catalytic market will continue to blossom. In an exclusive interview with, he said: “We believe that small exhaust suppliers have only two possibilities to survive – either as specialists in niche markets or as part of one of the global players. Exhaust suppliers must act globally and produce locally, in alignment with their global customers. This globalisation is only possible for companies of a certain size. Significant resources, both in terms of manpower and investment capital, are required to enable successful globalisation. It is unlikely that small companies can afford such an approach. This is why many small- and mid-sized companies have either disappeared or been acquired over the last ten years.”

Too much capacity
There is still too much capacity in the industry. Manufacturers are adjusting to changes in supply and demand. Tenneco is being forced to make major changes to its business as it faces the decline in aftermarket demand for exhausts in Europe. Tenneco has confirmed that it will close its Danish plant and halve capacity at the UK plant. French exhaust operations have already been cut from three plants to one and the Swedish plant has been refocused from aftermarket towards OE supply. The company has also closed exhaust warehouses in Spain and Romania and consolidated muffler-box production to a single small plant in Poland.

From a technical standpoint, recent innovations by the major manufacturers centre on enhanced gas-flow efficiency, improved heat insulation and, of course, noise and weight reduction. Sound engineering alone is increasingly becoming a major part of manufacturers’ development work as vehicle makers look for a specific exhaust system sound. Tenneco Automotive, for example, is currently producing controlled mufflers for VW, Audi, Peugeot and Citroën.

The company is also developing ‘active mufflers’ for a number of other customers, too. Karel Bos, chief executive officer of Bosal Group said: “There are various opportunities in technological developments at the cold end. With advances in the reduction of flow noise, semi-active noise attenuation and extremely precise value engineering, cost and weight reductions are now the major drivers. Bosal’s lightweight exhaust concept has a completely novel mounting system and can lead to a 40% weight reduction in comparison to a conventional system.”

From flow channelling to catalysis, today’s exhaust system has become a complex module with a decisive role to play in emissions control and acoustic comfort. The introduction of more stringent standards to reduce exhaust line noise and improve the acoustic quality at the tailpipe is presenting an opportunity for all manufacturers to enrich their systems and increase the value added.

Euro 4
When the Euro 4 regulations swing into force next year, passenger car exhaust systems will need even more content to reduce emissions. Although exhaust system manufacturers can expect to benefit from the greater demands of future Euro emission norms, some believe that the value of higher technical demands will be offset by continued downward pricing pressure from the vehicle makers. However, the potential blossoming gasoline (petrol) direct injection market in Europe could spell out good news for manufacturers.

These engines require more complex, higher-margin exhausts. Some growth could also come from higher-margin materials. Particle filters for the increasingly popular diesel-powered engines will come into their own over the next few years. Some manufacturers also expect to see growth emanating from regulations on vehicle noise.

Defining the functions –
The exhaust is one of the most highly stressed systems on a car. It must operate under extreme conditions – undergoing considerable changes in temperature. With severe vibration it is also subject to internal corrosion and damage from stones, mud, water and road salt.

The exhaust has three main functions – two environmental and one performance-related. The first function is to minimise carbon monoxide, unburned hydrocarbons and oxides of nitrogen, and direct them out of the engine and away from the passenger compartment. The second is to minimise noise created by the car’s engine. The third is to help optimise engine performance by providing a continuous, smooth flow of gas out of the engine.

The exhaust can also be ‘tuned’ to produce a distinctive and characteristic
note, such as that of a Porsche 911.

– and elements
On front-engined cars, the exhaust system runs from the engine, underneath the entire length of the car. It consists of seven different sections. From the engine to the tail pipe, the main components comprise the exhaust manifold, down pipe, catalytic converter, muffler/silencer and tail pipe.

The manifold is typically made out of cast iron and is used to allow hot gases to escape from the engine’s cylinders through to one main outlet into the down pipe.
A catalytic converter is a small honeycomb block of ceramic or steel strip, encased in a stainless steel housing and built into the exhaust system just behind the manifold. As exhaust gases pass through, harmful carbon monoxide, hydrocarbons and nitrogen oxides are converted into carbon dioxide, water vapour and nitrogen.

Expert Analysis
A global market review for OE exhaust systems – forecasts to 2007
Continuing our series of component market studies, this new report reviews the key market drivers for vehicle OE exhaust systems, providing you with forward-looking analysis for the European, Japanese and North American markets. Chapter two sets out our view of the market trends, identifying market shares for OE exhaust manufacturers in Europe, North America and globally. Chapter three then highlights recent technical advances while Chapter four will provide you with brief profiles of the major manufacturers, including ArvinMeritor, Bosal, Eberspächer, Faurecia and Tenneco Automotive. Find out more here.

The term ‘three-way catalyst’ refers to the three pollutants that are converted. As the name suggests, the main purpose of the muffler is to reduce both the noise and the amount of vapour to acceptable levels. It also helps to ensure the correct flow of gases passing through the exhaust system without restricting engine performance. Most exhaust systems have at least two mufflers located at the front and rear.

Exhaust noise is caused by expulsions of gas from the cylinders. To reduce this noise, sound energy must be reduced. This is achieved in two ways: absorption and reflection. By the absorption method, sound waves enter a porous material where energy is converted by friction into heat. The absorbent material consists of mineral wool or fibreglass. In the reflection process, sound waves are reflected by baffles; the advancing and retreating sound waves cancel themselves out.

Today, most exhaust systems use a combination of the two silencing methods. Overall, it is the precise engineering of an exhaust system – from the manifold that connects an engine’s exhaust ports to an exhaust pipe, to the catalytic converter that eliminates pollutants from the exhaust, to the muffler – leads to a pleasant, tuned engine sound, reduced pollutants and optimised engine performance.

Emissions legislation triggers catalytic converter innovation
Overall across Europe, high fuel prices are driving this trend toward diesel-powered cars. Moreover, carmakers are counting on diesels to reduce carbon dioxide emissions, a major contributor to global warming. European Union environment ministers aim to reduce average carbon dioxide emissions to 140 grams per kilometre by 2008. Regulators want a further reduction to 120 grams by 2010. Most new cars (gasoline and diesel) currently exceed 180 grams. About 95% of diesel engines are turbocharged.

“When Euro 4 goes into effect in 2005, internal combustion measures alone will no longer be sufficient for very heavy vehicles,” said Dr Ulrich Dohle, executive vice president of Bosch’s diesel systems division. “An efficient exhaust after-treatment with particulate filter and an additional DeNOx catalyst will become necessary for some vehicles. A similar development will occur for commercial vehicles.”