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Direct Injection (DI) is believed to be one of the key strategies for maximizing the thermal efficiency of Spark Ignition (SI) engines and meet the ever-tightening emissions regulations. This paper explores the use of Liquefied Petroleum Gas (LPG) liquid phase fuel in a 1.5 liter SI four cylinder gasoline engine with double over head camshafts, four valves per cylinder, and centrally located DI injector. The DI injector is a high pressure, fast actuating injector enabling precise multiple injections of the finely atomized fuel sprays. With DI technology, the injection timing can be set to avoid fuel bypassing the engine during valve overlap into the exhaust system prior to combustion. The fuel vaporization associated with DI reduces combustion chamber and charge temperatures, thereby reducing the tendency for knocking. Fuel atomization quality supports an efficient combustion process.

Cold start driving cycles exhibit an increase in friction losses due to the low temperatures of metal and media compared to normal operating engine conditions. These friction losses are responsible for up to 10% penalty in fuel economy over the official drive cycles like the New European Drive Cycle (NEDC), where the temperature of the oil even at the end of the 1180 s of the drive cycle is below the fully warmed up values of between 100°C and 120°C. At engine oil temperatures below 100°C the water from the blowby condensates and dilutes the engine oil in the oil pan which negatively affects engine wear. Therefore engine oil temperatures above 100°C are desirable to minimize engine wear through blowby condensate. The paper presents a new technique to warm up the engine oil that significantly reduces the friction losses and therefore also reduces the fuel economy penalty during a 22°C cold start NEDC.

Improvements of vehicle fuel economy may be achieved by the introduction of advanced internal combustion engines (ICE) improving the fuel conversion efficiency of the engine and of advanced power trains (PWT) reducing the amount of fuel energy needed to power the vehicle. The paper presents a novel design of a variable compression ratio advanced spark ignition engine that also permits an expansion ratio that may differ from the compression ratio hence generating an Atkinson cycle effect. The stroke ratio and the ratio of maximum to minimum in-cylinder volumes may change with load and speed to provide the best fuel conversion efficiency. The variable ratio of maximum to minimum in-cylinder volumes also improves the full load torque output of the engine.

Gasoline Direct Injection (DI) is a technique that was successful in motor sports several decades ago and is now relatively popular in passenger car applications only. DI gasoline fuel injectors have been recently improved considerably, with much higher fuel flow rates and much finer atomization enabled by the advances in fuel pressure and needle actuation. These improved injector performance and the general interest in reducing fuel consumption also in motor sports have made this option interesting again. This paper compares Port Fuel Injection (PFI) and DI of gasoline fuel in a high performance, four cylinder spark ignition engine for super bike racing. Computations are performed with a code for gas exchange, heat transfer and combustion, simulating turbulent combustion and knock.

Direct Injection (DI) is believed to be one of the key strategies for maximizing the thermal efficiency of Spark Ignition (SI) engines and meeting the ever-tightening emissions regulations. This paper explores the use of propane and methane gas fuels in a 1.5 liter SI four cylinder gasoline engine with double over head camshafts, four valves per cylinder, and a centrally located DI injector. With DI technology, the injection timing can be set to avoid fuel bypassing the engine during valve overlap into the exhaust system prior to combustion. DI of fuel reduces the embedded air displacement effects of gaseous fuels and lowers the charge temperature. Injection timings and compression ratio are optimized for best performances at Wide Open Throttle (WOT) conditions when configured to achieve homogeneous charge at stoichiometry or run lean jet controlled stratified.

This paper explores through engine simulations the use of LPG and CNG gas fuels in a 1.5 liter Spark Ignition (SI) four cylinder gasoline engine with double over head camshafts, four valves per cylinder equipped with a novel mixture preparation and ignition system comprising centrally located Direct Injection (DI) injector and Jet Ignition (JI) nozzles. With DI technology, the fuel may be introduced within the cylinder after completion of the valve events. DI of fuel reduces the embedded air displacement effects of gaseous fuels and lowers the charge temperature. DI also allows lean stratified bulk combustion with enhanced rate of combustion and reduced heat transfer to the cylinder walls creating a bulk lean stratified mixture.

Recovery of kinetic energy during driving cycles is the most effective option to improve fuel economy and reduce green house gas (GHG) emissions. Flywheel kinetic energy recovery systems (KERS) may boost this efficiency up to values of about 70%. An engine and vehicle model is developed to simulate the fuel economy of a compact car equipped with a TDI diesel engine and a KERS. Introduction of KERS reduces the fuel used by the 1.6L TDI engine to 3.16 liters per 100 km, corresponding to 82.4 g of CO₂ per km. Downsizing the engine to 1.2 liters as permitted by the torque assistance by KERS, further reduces the fuel consumption to 3.04 liters per 100 km, corresponding to 79.2 g of CO₂ per km. These CO₂ values are 11% better than those of today's most fuel efficient hybrid electric vehicle.

Downsizing and Turbo Charging (TC) and Direct Injection (DI) may be combined with Variable Valve Actuation (VVA) to better deal with the challenges of fuel economy enhancement. VVA may control the load without throttle; control the valve directly and quickly; optimize combustion, produce large volumetric efficiency. Benefits lower fuel consumption, lower emissions and better performance and fun to drive. The paper presents an engine model of a 1.6 litre TDI VVA engine specifically designed to run pure ethanol, with computed engine maps for brake specific fuel consumption and efficiency. The paper also presents driving cycle results obtained with a vehicle model for a passenger car powered by this engine and a traditional naturally aspirated gasoline engine. Preliminary results of the VVA system coupled with downsizing, turbo charging and Direct Injection permits significant driving cycle fuel economies.

Recovery of braking energy during driving cycles is the most effective option to improve fuel economy and reduce green house gas (GHG) emissions. Hybrid electric vehicles suffer the disadvantages of the four efficiency-reducing transformations in each regenerative braking cycle. Flywheel kinetic energy recovery systems (KERS) may boost this efficiency up to almost double values of about 70% avoiding all four of the efficiency-reducing transformations from one form of energy to another and keeping the vehicle's energy in the same form as when the vehicle starts braking when the vehicle is back up to speed. With reference to the baseline configuration with a 1.6 liters engine and no recovery of kinetic energy, introduction of KERS reduces the fuel usage to 3.16 liters per 100 km, corresponding to 82.4 g of CO₂ per km. The 1.6 liters Turbo Direct Injection (TDI) diesel engine without KERS uses 1.37 MJ per km of fuel energy, reducing with KERS to 1.13 MJ per km.

The paper compares Road Racing World Championship Grand Prix (WGP) engine solutions developed in compliance with the 2002 Federation Internationale de Motocyclisme (FIM) Technical Regulations. Ad-hoc assumptions, similarity rules and nondimensional parameters from previous projects are used to define geometric and operating parameters for partly similar engine solutions basically differing in the number of cylinders, three, four, five or six, and the cylinder layout, in-line or V-angle. Results are shown as computed classical engine outputs versus engine speed, including brake, indicated and friction values. By increasing the number of cylinders, charging efficiency reduces, while thermal efficiency increases. Higher values of brake torque and power and lower values of brake specific fuel consumption are provided by the V-angle six cylinder engine.

Real driving cycles are characterized by a sequence of accelerations, cruises, decelerations and engine idling. Recovering the braking energy is the most effective way to reduce the propulsive energy supply by the thermal engine. The fuel energy saving may be much larger than the propulsive energy saving because the ICE energy supply may be cut where the engine operates less efficiently and because the ICE can be made smaller. The present paper discusses the state of the art of hydro-pneumatic drivelines now becoming popular also for passenger cars and light duty vehicle applications permitting series and parallel hybrid operation. The papers presents the thermal engine operation when a passenger car fitted with the hydro-pneumatic hybrid driveline covers the hot new European driving cycle. From a reference fuel consumption of 4.71 liters/100 km with a traditional driveline, the fuel consumption reduces to 2.91 liters/100 km.

This paper presents experimental and computational results obtained on an in line, six cylinder, naturally aspirated, gasoline engine. Steady state measurements were first collected for a wide range of cam and spark timings versus throttle position and engine speed at part and full load. Simulations were performed by using an engine thermo-fluid model. The model was validated with measured steady state air and fuel flow rates and indicated and brake mean effective pressures. The model provides satisfactory accuracy and demonstrates the ability of the approach to produce fairly accurate steady state maps of BMEP and BSFC. However, results show that three major areas still need development especially at low loads, namely combustion, heat transfer and friction modeling, impacting respectively on IMEP and FMEP computations. Satisfactory measurement of small IMEP and derivation of FMEP at low loads is also a major issue.

Direct injection and jet ignition is becoming popular in electrically assisted, turbocharged, F1 engines because of the pressure to reduce fuel consumption. Operation from homogeneous stoichiometric up to lean of stoichiometry stratified about λ = 1.5, occurs with fast combustion of reduced cyclic variability thanks to the enhanced ignition by multiple jets of hot, partially reacting products travelling through the combustion chamber. The fuel consumption has thus been drastically reduced in an engine that is, however, still mostly throttle controlled. The aim of the present paper is to show the advantages of direct injection and jet ignition based on model simulations of the operation of a high-performance throttle-controlled engine featuring rotary valves.