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High engine efficiency and low emissions on spark ignition engines can be achieved with a new camshaft profile switching device. This enables the use of two camshaft profiles for inlet and exhaust that can be switched independent of each other by any engine management input. This paper proposes the use of this device to give an excellent torque curve together with reduced emissions, by selecting from two discrete inlet and exhaust camshaft profiles and timings against engine parameters such as speed, load and temperature.

Five different fuels, including gasoline, commercial E85, pure methanol and two mixtures of gasoline, ethanol and methanol, (GEM), configured to a target stoichiometric air fuel ratio have been investigated in a fully-optically-accessed engine. The work investigated effects of injection duration, and performed spray imaging, thermodynamic analysis of the combustion and OH imaging, for two fixed engine conditions of 2.7 and 3.7 bar NMEP at 2000 rpm. The engine was operated with constant ignition timing for all fuels and both loads. One of the most important results from this study was the suitability of a single type of injector to handle all the fuels tested. There were differences observed in the spray morphology between the fuels, due to the different physical properties of the fuels. The energy utilisation measured in this study showed differences of up to 14% for the different GEM fuels whereas an earlier in-vehicle study had showed only 2 to 3%.

Many new technologies are being developed to improve the fuel consumption of gasoline engines, including the combination of direct fuel injection with turbocharging in a so-called ‘downsizing’ approach. In such spark ignition engines operating on the Otto cycle, downsizing targets a shift in the operating map such that the engine is dethrottled to a greater extent during normal operation, thus reducing pumping losses and improving fuel consumption. However, even with direct injection, the need for turbine protection fuelling at high load in turbocharged engines - which is important for customer usage on faster European highways such as German Autobahns - brings a fuel consumption penalty over a naturally-aspirated engine in this mode of operation.

The control of Homogeneous Charge Compression Ignition (HCCI) (also known as Controlled Auto Ignition (CAI)) has been a major research topic recently, since this type of combustion has the potential to be highly efficient and to produce low NOx and particulate matter emissions. Ion current has proven itself as a closed loop control feedback for SI engines. Based on previous work by the authors, ion current was acquired through HCCI operation too, with promising results. However, for best utilization of this feedback signal, advanced interpretation techniques such as artificial neural networks can be used. In this paper the use of these advanced techniques on experimental data is explored and discussed. The experiments are performed on a single cylinder cam-less (equipped with a Fully Variable Valve Timing (FVVT) system) research engine fueled with commercially available gasoline (95 ON).

Homogenous Charge Compression Ignition (HCCI) is an alternative to Spark Ignited (SI) combustion, which can provide part-load efficiencies as high as compression ignition engines and energy densities as high as SI engines, without high levels of NOx or Particulate Matter (PM). The principle of operation involves reaching the thermal oxidization barrier of a homogeneous air-fuel mixture. This combustion practice is enabled by diluting then compressing the mixture with the Trapped Residual Gases (TRG) to dilute the initial charge thus keeping combustion temperatures down. Introduction of exhaust gasses in the mixture can be achieved by the use of early exhaust valve closure and late inlet valve opening. The charge is well mixed avoiding particulate emissions, and by using exhaust gasses for load regulation the need for throttled operation is removed allowing the realization of high efficiencies, low pumping losses and a resulting 15 - 20% improvement in fuel economy.

The tumble flow in modern spark ignition engines is assuming an evermore important role for fuel guiding, air/fuel mixing and the generation of turbulence kinetic energy to enhance the combustion process. This paper describes results obtained with laser Doppler anemometry in multiple vertical planes in the cylinder of a motored, tumble flow engine and looks at the post processed data in terms of tumble ratios and mean and turbulence kinetic energies. The tumble results indicate very different flow fields in parallel planes lying in the main tumble direction, showing the complex nature of the flows in the cylinder. A simple method of integrating the tumble ratios from the different planes is suggested, leading to a tumble ratio more in line with those expected from an integrated method of measuring tumble, albeit these results are crank angle dependent. The tumble in a perpendicular plane shows unexpected asymmetries and values for the tumble.

There is a great deal of interest in new technologies to assist in reducing the CO2 output of passenger vehicles, as part of the drive to meet the limits agreed by the EU and the European Automobile Manufacturer's Association ACEA, itself a result of the Kyoto Protocol. For the internal combustion engine, the most promising of these include gasoline direct injection, downsizing and fully variable valve trains. While new types of spray-guided gasoline direct injection (GDI) combustion systems are finally set to yield the level of fuel consumption improvement which was originally promised for the so-called ‘first generation’ wall- and air-guided types of GDI, injectors for spray-guided combustion systems are not yet in production to help justify the added complication and cost of the NOx trap necessary with a stratified combustion concept.

The paper discusses the concept, specification and performance of a new, dedicated range extender engine for plug-in series hybrid vehicles conceived and designed by Lotus Engineering. This has been undertaken as part of a consortium project called Limo Green, part-funded by the UK government. The Lotus Range Extender engine has been conceived from the outset specifically as an engine for a plug-in series hybrid vehicle, therefore being free of some of the constraints placed on engines which have to mate to conventional, stepped mechanical transmissions. The paper starts by defining the philosophical difference between an engine for range extension and an engine for a full series hybrid vehicle, a distinction which is important with regard to how much power each type must produce. As part of this, the advantages of the sparkignition engine over the diesel are outlined.

The Swedish Biomimetics 3000's μMist® platform technology has been used to develop a radically new injection system. This prototype system, developed and characterized with support from Lotus, as part of Swedish Biomimetics 3000®'s V₂IO innovation accelerating model, delivers improved combustion efficiency through achieving exceptionally small droplets, at fuel rail pressures far less than conventional GDI systems and as low as PFI systems. The system gives the opportunity to prepare and deliver all of the fuel load for the engine while the intake valves are open and after the exhaust valves have closed, thereby offering the potential to use advanced charge scavenging techniques in PFI engines which have hitherto been restricted to direct-injection engines, and at a lower system cost than a GDI injection system.