As the global car industry faces increased scrutiny following the Volkswagen emission scandal, there is no doubt that this revelation will have an impact on our market and the future of diesel, but to what extent?

Volkswagen has admitted that it circumvented the emissions control system in over 480,000 2.0-liter diesel vehicles sold in the United States since 2008, to meet strict NOx emission test regulations.

Euro Emission Standards

European emission standards define the acceptable limits for exhaust emissions of new vehicles sold in EU member states and were first introduced in 1992.

Euro 1 (July 1992)  Initiated the switch to unleaded petrol and the universal fitting of catalytic converters to petrol cars to reduce carbon monoxide (CO).

Euro 2 (January 1996)  Further reduced the limit for CO emissions and introduced different emissions limits for diesel and petrol vehicles.

Euro 3 (January 2000)  Added a separate NOx limit for diesel engines and introduced separate Hydrocarbon (HC) and NOx limits for petrol engines.

Euro 4 (January 2005)  Concentrated on cleaning up emissions from diesel cars, reducing particulate matter (PM) and oxides of nitrogen (NOx). Some Euro 4 diesel cars were fitted with particulate filters.

Euro 5 (September 2009)  Tightened the limits on particulate emissions from diesel engines and all diesel cars needed particulate filters to meet the new requirements. For the first time, a particulates limit was set for petrol engines.

Euro 6 (September 2015)  Imposed a significant reduction in NOx emissions from diesel engines (a 67% reduction compared to Euro 5). Also established similar standards for petrol and diesel.

Overall, since Euro 1, PM levels have been reduced by 96% and NOx levels by 87%. To achieve this, new technologies have been developed and adapted to fit vehicle exhaust systems.

Emission Reducing Technologies

Catalytic converters, originally launched in the 1970’s, were designed to clean up CO and HC particulates released as part of the engine combustion process. They react to temperature, converting CO and HC to Carbon Dioxide and water. The reaction depends upon a certain temperature being achieved so they do not work as efficiently in colder
climates.

DPF’s were introduced from January 2005 where diesel particulate levels were reduced to extremely low levels. This reduces the allowable size of PM released to the atmosphere. Reducing the size of PM from the combustion process to this level was not technically possible. This meant all diesel vehicles after September 2009 were fitted with a filter to capture soot and other harmful particles, preventing them entering the atmosphere. A DPF can remove around 85% of the particulates from the exhaust.

To tackle the reduction of NOx, Selective Catalytic Reduction (SCR) systems were introduced in 2010. The SCR system is where Urea (AdBlue) is injected into the exhaust post combustion. In the exhaust, the fluid is converted into ammonia (NH3) which reacts with the NOx in the ‘NOx accumulator,’ breaking the chemical bond and converting NOx into Nitrogen and water. SCR technology alone can achieve NOx reductions by up to 90%, and is one of the most cost-effective and fuel-efficient technologies available to help reduce diesel engine emissions. However, in real world driving conditions, the SCR systems do not work as efficiently and can produce much higher emissions when compared to laboratory testing conditions.

Not over yet…

When the emission levels were set, most engine manufacturers didn’t believe that they were achievable in the set time frames. In the absence of revised levels, the manufacturers have made great progress developing the new DPF and SCR systems. However, the method for testing and proving that the systems do actually achieve the set levels have been flawed; this has allowed manufacturers to achieve the correct levels in lab conditions. But, these do not relate to the actual emissions produced in real world driving conditions. This is now at the heart of the VW scandal.

Find out more about what’s going on in the industry…

 

Parts Design Improvements -There has been much discussion within the automotive repair industry about the differences between using OEM parts and the aftermarket equivalent repair parts. In this article, with a focus on turbochargers; we explore the benefits associated with using high quality repair parts and why such parts can actually improve a turbo repair.   Continue reading “Melett Parts Design Improvements – Better than OE?”

Today’s automotive repair industry is faced with an overwhelming range of repair parts. Amid claims of exceptional quality at extraordinarily cheap prices, here Martyn Howorth, Sales Director, Melett Ltd., explores the reasons why some turbocharger components are offered at such low prices, and what the real cost of these low quality parts means to the repair industry.

Continue reading “Is the Price Right?”

Air Flow Rig – There has been an ongoing debate for many years between the original turbocharger manufacturers and the turbocharger repair industry, over whether a turbo can be repaired.

This debate has been raging for over 10 years. Some OEM turbo manufacturers pulled out of the repair market around 2004; at this time their argument was that most repairers did not have the correct specialist balancing equipment for the new higher speed turbos.

Over the last decade, vehicle technology has continued to improve to reduce emission levels in order to meet the Euro 4, 5 then 6 regulations. As a result of these changes, engine and turbo technology has increased in complexity. As well as the settings and control of advancements, such as the Variable Nozzles, have become more critical to the correct operation of the turbo. This is now presenting new challenges to turbo repairers as the correct setting of the turbo on later models, now requires further specialist equipment in the form of an Air Flow Rig.

What is a Variable Nozzle Turbo?

When a turbocharger is matched to an engine, the Engineers have to balance the low speed response with high speed efficiency. The variable nozzle (also referred to as a variable geometry), is designed to change the exhaust gas inlet area with the engine speed to closely match the desired boost requirements of the engine. For low speed response, the nozzle vanes move to the ‘closed vane’ position to reduce the nozzle area – this increases gas speed through the turbo giving improved response at low engine speeds – similar to squeezing the end of a hose pipe to make the jet of water more powerful. As the engine speed increases, the actuator moves the nozzle vanes to the fully open position to maximize the exhaust gas flow.

Vane Setting Accuracy

When the first variable nozzle turbos were launched, it was a step change in turbocharging technology.  Air mass sensors and ECU’s were programmed to manage the whole engine system, however relative to the current engines, tolerances for acceptable air flow were set quite high. When setting up a new turbo, vane setting positions are set using accurate air flow equipment, which ensures that the ‘minimum vane opening’ position is set to allow a specific mass of air flow through the vanes. If the vanes are too closed, this can cause choking of the engine and overspeeding of the turbine. If it is set too large, the turbo will have too much ‘lag’ and not respond as well as it should.

Traditionally, turbo repair workshops did not use an air flow rigs to correctly set the flow. The actuator position was set based upon an accurate measured position of the actuator arm. This produced acceptable results and allowed the repairers to keep on repairing.

In reality, this method of setting the vanes can produce quite large inaccuracies in the flow of air. The actuator arm measurement is set against a cast finish on the bearing housing, the position of which is not accurately controlled during manufacture. However, as the engine would accept quite a large tolerance of air flow, the repaired turbo still performed well compared to the broken turbo which it replaced, so the vehicle owner was still happy with the results. On older turbo repairs, the variable nozzle position had to be a long way out before the performance was unacceptably affected or for the ECU to flag a problem.  From an OEM perspective, this is not acceptable and is the reason for their lack of support of repairing.

The need for accurate air flow setting of turbos was well understood by reputable repairers, and hence some quality repairers developed their own air flow equipment to accurately set their turbos, resulting in a reduction in warranties and the ability to build on their reputation as a quality repairer.

Today’s Turbos

In more recent years, as engines have improved to meet tighter Euro emission regulations, the control over the whole air / fuel system has improved dramatically. Many premium brand vehicles have moved to electronic actuation which gives positional feedback to the ECU. Some more advanced turbo controllers now sit within the CANbus talking directly to the injection system and air mass sensors, to respond more quickly to engine demands. For these turbos, the settings are either correct and accepted by the ECU –  or not which results in warning lights, limp home mode or refusal to start.

As more of the Euro 5 compliant vehicles enter the aftermarket, problems will arise and for some turbo models, we have already reached the point where flowing the turbo is a necessity and only possible by workshops who have the correct equipment. However, this will naturally mean that older turbos also become more widely repaired using air flow equipment, which will bring further improvements to the market.

Making the Right Choice

Traditionally, in the turbocharger aftermarket the customer had a choice between a new OE turbo and a remanufactured turbo. Over the past 10 years the turbo repair market has changed significantly with the number of new repairers entering the market and the number of suppliers of parts. What we now have is three tiers, a new OE turbo, a high quality remanufactured turbo repaired using quality parts and the correct equipment, and a poor quality repaired turbo, using inferior quality low cost parts. There will always be a market for all three options depending upon the vehicle owner’s requirements.

It is important that garages understand that there are different levels of quality for repaired turbos and therefore a different level of associated cost.  When outsourcing turbo repairs it is crucial to consider the real cost of replacing a turbo and to educate your customer about the different options and associated risks for going lowest cost vs paying a little more for quality, so they can make informed decisions. Who pays for the time to fit the second replacement? What if it damages other parts of the engine?

Many turbo specialists already have a flow rig and are repairing turbos to an excellent standard. It is a fact that warranties are reduced when turbos are repaired using quality parts as well as the correct repair equipment.

More Information

To request further details about Melett, including information about where you can find your local quality turbo repair specialist, email: [email protected]

 

Traditionally compressor wheels are produced from aluminium, which is naturally a very weak cast material.

Aluminium is the preferred material for compressor wheels as it is a relatively simple and inexpensive process to cast the compressor wheels. However, to create a stronger wheel post-process treatments are essential.  Continue reading “The Real Cost of Compressor Wheels”