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To meet increasingly stringent emissions and fuel economy regulations, many Original Equipment Manufacturers (OEMs) have recently developed and deployed small, high power density engines. Turbocharging, coupled with gasoline direct injection (GDI) has enabled a rapid engine downsizing trend. While these turbocharged GDI (TGDI) engines have indeed allowed for better fuel economy in many light duty vehicles, TGDI technology has also led to some unintended consequences. The most notable of these is an abnormal combustion phenomenon known as low speed pre-ignition (LSPI). LSPI is an uncontrolled combustion event that takes place prior to spark ignition, often resulting in knock, and has been known to cause catastrophic engine damage. LSPI propensity depends on a number of factors including engine design, calibration, fuel properties and engine oil formulation. Several engine tests have been developed within the industry to better understand the phenomenon of LSPI.

Improvements in vehicle fuel efficiency continue to be a significant driver for all parties involved in the operation of automotive vehicles. The cost of vehicle ownership, energy security and the need to limit greenhouse gas emissions are all factors in driving the need to improve operating efficiency. One particular area of interest is engine lubricants which are known to have a significant effect on the overall efficiency of a vehicle. The decision to move to a more fuel efficient lubricant is enhanced since the incremental cost of introducing a fuel efficient lubricant is low in comparison to the potential fuel saving leading to a favourable economic decision for a fleet owner. This paper describes a study undertaken where upon two significantly different UK buses were taken directly from the FirstGroup fleet and used for a period of two weeks for fuel economy testing. The testing centres on two commercially available engine lubricants and was completed on a test track in the UK.

Downsized gasoline engines, coupled with gasoline direct injection (GDI) and turbocharging, have provided an effective means to meet both emissions standards and customers’ drivability expectations. As a result, these engines have become more and more common in the passenger vehicle marketplace over the past 10 years. To maximize fuel economy, these engines are commonly calibrated to operate at low speeds and high engine loads – well into the traditional ‘knock-limited’ region. Advanced engine controls and GDI have effectively suppressed knock and allowed the engines to operate in this high efficiency region more often than was historically possible. Unfortunately, many of these downsized, boosted engines have experienced a different type of uncontrolled combustion. This combustion occurs when the engine is operating under high load and low speed conditions and has been named Low Speed Pre-Ignition (LSPI). LSPI has shown to be very damaging to engine hardware.

Requirements to improve vehicle fuel economy continue to increase, spurred on by agreements such as the Kyoto Protocol. Lubricants can play a role in aiding fuel economy, as evidenced by the rise in the number of engine oil specifications that require fuel economy improvements. Part of this improvement is due to achieving suitable viscometric properties in the lubricant, but additional improvements can be made using friction modifier (FM) compounds. The use of FMs in lubricants is not new, with traditional approaches being oleochemical-based derivatives such as glycerol mono-oleate and molybdenum-based compounds. However, to achieve even greater improvements, new new friction modifying compounds are needed to help deliver the full potential required from next generation lubricants. This work looks at the potential improvements available from new FM technology over and above the traditional FM compounds.

For many years, governments have driven the improvement of fuel economy in transportation through tightening legislation. This effort has focused on passenger cars, but is increasingly concerned with heavy-duty vehicles (HDV). The combination of this regulatory focus with the ever present desire for low cost of ownership in commercial vehicles is giving increased pressure to deliver more fuel efficiency from the lubricants. In order to deliver improved fuel efficiency, suitable test methodology is needed to give repeatable discriminatory results that not only help in the advance of technology, but can also highlight the magnitude of the benefit expected in real-world applications. Typical on-road driving has significant variation in fuel consumption due to driver inconsistency, changes in rolling resistance and changeable ambient conditions.

Over several years, a fuel economy test measurement technique has been developed to highlight the magnitude of benefits expected in real world applications of different heavy-duty vehicle (HDV) engine oils in an operating vehicle. This method provides discriminatory results using an alternative to the widely used gravimetric fuel measurement methodology of Brake Specific Fuel Consumption (BSFC), in order to measure gains of <2% in a more repeatable manner. For the results to prove meaningful to the wider commercial audience, such as vehicle operators, original equipment manufacturers and oil providers, the systemic test vehicle operating conditions need to closely represent on-road conditions experienced on a daily basis by long haul, heavy duty diesel vehicles. This paper describes the parameters, necessary measures and methodologies required to record real world data and create representative proving ground test cycles.

It has long been understood that the piston assembly of the internal combustion engine accounts for a significant proportion of total engine friction. Modern engines are required to have better fuel economy without sacrificing durability. The pursuit of better fuel economy drives trends like downsizing, turbocharging and direct injection fuelling systems that increase cylinder pressures and create a more arduous operating environment for the piston ring / cylinder bore tribocouple. The power-cylinder lubricant is therefore put under increased stress as modern engine technology continues to evolve. The conventional approach to investigating fundamental power-cylinder tribology employs bench-tests founded on assumptions which allow for simplification of experimental conditions.