Common Rail Direct Injection Research Articles

COMBUSTION AND EMISSIONS CHARACTERISTICS OF A COMPRESSION IGNITION ENGINE FUELLED WITH N-BUTANOL BLENDS

The use of biomass based renewable fuel, n-butanol blends for compression ignition (CI) engine has attracted wide attention due to its superior properties such as better miscibility, higher energy content, and cetane number as compared to other alternatives fuel. In this present study the use of n-butanol 10% blends (Bu10) with diesel fuel has been tested using multi-cylinder, 4-stroke engine with common rail direct injection system to investigate the combustion and emissions of the blended fuels. Based on the tested engine at BMEP=3.5Bar. Based on the results Bu10 fuel indicates lower first and second peak pressure by 5.4% and 2.4% for engine speed 1000rpm and 4.4% and 2.1% for engine speed 2500rpm compared to diesel fuel respectively. Percentage reduction relative to diesel fuel at engine speeds 1000rpm and 2500rpm for Bu10: Exhaust temperature was 7.5% and 5.2% respectively; Nitrogen oxides (NOx) 73.4% and 11.3% respectively.

Combustion and emissions characteristics of a compression ignition engine fueled with n-butanol blends

The use of biomass based renewable fuel, n-butanol blends for compression ignition (CI) engine has attracted wide attention due to its superior properties such as better miscibility, higher energy content, and cetane number. In this present study the use of n-butanol 10% blends (Bu10) with diesel fuel has been tested using 4-cylinder, 4-stroke common rail direct injection CI engine to investigate the combustion and emissions of the blended fuels. Based on the tested engine at BMEP=3.5Bar Bu10 fuel indicates lower first and second peak pressure by 5.4% and 2.4% for engine speed 1000rpm and 4.4% and 2.1% for engine speed 2500rpm compared to diesel fuel respectively. Percentage reduction relative to diesel fuel at engine speeds 1000rpm and 2500rpm for Bu10: Exhaust temperature was 7.5% and 5.2% respectively; Nitrogen oxides (NOx) 73.4% and 11.3% respectively.

Performance and emissions of a CRDI diesel engine fuelled with swine lard methyl esters–diesel mixture

Biodiesel, as a product of the transesterification reaction of fatty material, is gaining appreciation all over the world and confirms its beneficial effect on the reduction of exhaust gases when (even partly) used to power compression-ignition engines. Although many researchers have focused on biofuel production and its application in combustion engines, continuous development of injection systems, providing new control strategies, encourages the seeking for new ways of optimizing biofuel combustion. In particular, very little attention has been given to the possibility of using biofuels in modern CRDI (Common Rail Direct Injection) engines with divided injection technology. There is also limited information available on engines operating on biodiesel of animal origin and their performance and emissions for such fuels.Because of this gap of knowledge, in the present study, the authors focused on analysing the phenomena of combustion of animal-origin biodiesel mixtures in a CRDI engine. Swine lard methyl esters, obtained in the laboratory by a single-step alkali transesterification process as a biocomponent, and mineral diesel were used to obtain B25, B50, B75 mixtures (25%, 50% and 75% of biocomponent concentration by volume). The physicochemical parameters of B25, B50, B75, pure esters and mineral diesel were examined to determine whether the fuels met quality standards. The mixtures were used to fuel a 2.6L Andoria CRDI engine placed on a dynamometer test stand. Tests were carried out in steady state operation, at rotational speeds when two different injection strategies occur (single injection and two subsequent injections), also different load conditions were introduced during tests. During the tests, engine performance and exhaust gas emissions were measured and analysed in detail.The study has confirmed the capability of using diesel–biodiesel mixtures containing up to 75% biocomponents in a modern CRDI engine without any operational issues. A minor deterioration of fuel performance parameters with an increasing biodiesel share has been observed. Brake-specific fuel consumption increased on average by 3.2%, 8.5% and 13.8% for B25, B50 and B75, respectively. An average reduction of brake fuel conversion efficiency was observed, amounting to 1.6%, 4.8% and 7.8% for B25, B50 and B75, respectively. Significant reduction of exhaust gas emissions (excluding NOx) and opacity was also observed in all examined operation conditions. Total hydrocarbon concentration was reduced by a maximum of 72% for the B75 mixture for a speed of 1500RPM and 100Nm load. The best emission performance was observed for operation conditions when a short pre-injection occurred early in the compression phase, before the main fuel injection. This has proven that advanced injection strategies can be applied to fuel mixtures with high biodiesel share, especially for low engine load conditions.

Combustion, performance and emissions characteristics of a newly developed CRDI single cylinder diesel engine

For improving engine performance, combustion and controlling emissions from compression ignition (CI) engines, common rail direct injection (CRDI) technology offers limitless possibilities by controlling fuel injection parameters such as fuel injection pressure, start of injection (SOI) timing, rate of fuel injection and injection duration. CRDI systems available commercially are quite complex and use a large number of sensors, hardware and analytical circuits, which make them very expensive and unfeasible for cheaper single cylinder engines, typically used in agricultural sector and decentralized power sector.This paper covers experimental investigations of a simpler version of CRDI system developed for a constant-speed, single-cylinder engine. Modifications in the cylinder head for accommodating solenoid injector, designing injector driver circuit and development of high pressure stage controls were some of the engine modification and development tasks undertaken. SOI timing is an important parameter for improving engine’s combustion characteristics. SOI timings were varied between 25° and 40° BTDC for investigating engine’s performance, emissions and combustion characteristics. Advanced fuel injections showed higher heat release rate (HRR), cylinder pressure and rate of pressure rise (RoPR) because of relatively longer ignition delay experienced. Lowest brake specific fuel consumption (BSFC) was obtained for 34° CA BTDC SOI. Reduction in engine out emissions except NOx was observed for advanced fuel injection timings for this newly developed CRDI system.

Zero-Dimensional Analysis of Combustion in a Multiple-Injection CRDI Engine Using Wiebe Law

Common rail direct injection system (CRDI) offers the potential to achieve optimal combustion and emission characteristics. An empirical analysis of engine combustion process incorporating Wiebe type burn rate law approach is useful not only in understanding the combustion characteristics of a CRDI engine but also aids in diagnosis and control of the combustion process wherever required from the performance and emission standpoint. This paper presents a methodology for applying the burn rate law for common rail direct injection diesel engines adopted with split injection by using Wiebe’s correlation. The analysis reveals that while the empirical constant ‘m’ (shape factor) for both pilot and main injections is independent of engine load and seems to be affected by engine speed only, the constant ‘a’ (efficiency parameter) seems to be influenced by the engine speed, load and injection conditions. A correlation for these empirical constants with the respective parameters of dependence can be formulated which can be used to analyze the effect of change in engine operating conditions on combustion characteristics without conducting engine experiments.

Influence of Engine Speed on Mixing and Emission Characteristics of Multiple-Injection Common Rail Direct Injection Diesel Engine

Increase in engine speed increases the in-cylinder turbulence and hence the rate of mixing. However, it is difficult to directly measure the mixing rate and relating its effect on emissions. Hence, in this paper, the comparison of mixing rate at different engine speeds are demonstrated with a multi-zone phenomenological model which has been developed and validated on a wide range of engine operating conditions. The mixing rate is evaluated using a standard quasi-dimensional k-ε formulation. The quantitative predictions of mixing rates at different engine speed substantiate the cause of soot emission reduction at higher engine speed.

Robust Indicated Mean Effective Pressure and Combustion Lambda Feedback Control for Lean NOx Trap Regeneration in a 2.2 L Common Rail Direct Injection Diesel Engine

To meet stringent Euro-6 emission regulations, a lean NOx trap (LNT) catalyst should be considered to effectively abate NOx emissions. This LNT catalyst should be periodically regenerated without deteriorating driving quality and also satisfy emission constraints, such as CO, low particulate matter or smoke, and low O2 during the regeneration phase. As a means of reductant delivery, in-cylinder post fuel injection with a feedforward (FF) control has been applied due to its simple implementation in an engine management system (EMS). However, with this method, it is difficult to satisfy the driving quality and emission constraints during the transition to or out of the regeneration phase. To solve this problem, we propose a novel LNT regeneration control method using an indicated mean effective pressure (IMEP) and a combustion lambda feedback (FB) control combined with the FF control. For the precise FB control of the post injection timing, among the location of the second rate of heat release (ROHR) peak, the magnitude of the second ROHR peak, and IMEP, the IMEP was selected as a control parameter because of its lowest cyclic variation. In addition, the exhaust lambda control was applied for the accurate FB control of the post injection quantity. The proposed method was implemented in an in-house EMS. The performance in several engine tests indicated that the torque fluctuation was minimized and all emission constraints were effectively satisfied. Furthermore, this method was also robust with regard to the thermal disturbance.

Particulate Emissions From Karanja Biodiesel Fueled Turbocharged CRDI Sports Utility Vehicle Engine

Biodiesel has emerged as one of the most promising alternative fuel to mineral diesel in last two decades globally. Lower blends of biodiesel emit fewer pollutants, while easing pressure on scarce petroleum resources, without sacrificing engine power output and fuel economy. However, diesel engines emit significant amount of particulate matter (PM), most of which are nanoparticles. Due to the adverse health impact of PM emitted by compression ignition (CI) engines; most recent emission legislations restrict the total number of particles emitted, in addition to PM mass emissions. Use of biodiesel leads to reduction in PM mass emissions; however, the particle size–numbers distribution has not been investigated thoroughly. In this paper, PM emission characteristics from Karanja biodiesel blends (KB20 and KB40) in a modern common rail direct injection (CRDI) engine used in a sports utility vehicle (SUV) with a maximum fuel injection pressure of 1600 bar have been reported. This study also explored comparative effect of varying engine speeds and loads on particulate size–number distribution, particle size–surface area distribution, and total particulate number concentration from biodiesel blends vis-à-vis baseline mineral diesel. This study showed that particulate number emissions from Karanja biodiesel blends were relatively higher than baseline mineral diesel.

Experimental study on fuel economies and emissions of direct-injection premixed combustion engine fueled with gasoline/diesel blends

The effects of gasoline/diesel blended fuel composed of diesel fuel with gasoline as additives in volume basis, on combustion, fuel economies and exhaust emissions were experimentally investigated. Tests were carried out based on a turbocharged Common-rail Direct Injection engine at a constant engine speed of 1800r/min and different loads of 3.2bar, 5.1bar Indicated Mean Effective Pressure. Additionally, the effect of combustion phasing and Exhaust Gas Recirculation were evaluated experimentally for various fuels. The results indicated that with the fraction of gasoline increasing in blends, the ignition delay was prolonged and the combustion phasing was retarded with the common injection timing. This led to a significant increase of premixed burning phase, which was in favor of smoke reduction; although, too much gasoline might be adverse to fuel consumption. An optimum combustion phasing was identified, leading to a higher thermal efficiency and better premixed combustion with blended fuels. A combined application of Exhaust Gas Recirculation and blended fuel with a high gasoline fraction was confirmed effective in reducing the oxides of nitrogen and smoke emissions simultaneously at the optimum combustion phasing without giving significant penalty of fuel consumption. A compound combustion mode with its emission lower than the conventional Compression Ignition engines, and efficiency higher than the typical Spark Ignition engines, could be achieved with a cooperative control of Exhaust Gas Recirculation and combustion phasing of the gasoline/diesel blended fuels.

Experimental investigations on a CRDI system assisted diesel engine fuelled with aluminium oxide nanoparticles blended biodiesel

Experiments were conducted to determine engine performance, exhaust emissions and combustion characteristics of a single cylinder, common rail direct injection (CRDI) system assisted diesel engine using diesel with 25 percentage of zizipus jujube methyl ester blended fuel (ZJME25). Along with this ZJME25 aluminium oxide nanoparticles were added as additive in mass fractions of 25ppm (AONP 25) and 50ppm (AONP 50) with the help of a mechanical Homogenizer and an ultrasonicator. It was observed that aluminium oxide nanoparticles blended fuel exhibits a significant reduction in specific fuel consumption and exhaust emissions at all operating loads. At the full load, the magnitude of HC and smoke emission for the ZJME25 before the addition of aluminium oxide nanoparticles was 13.459g/kWh and 79 HSU, whereas it was 8.599g/kWh and 49 HSU for the AONP 50 blended ZJME25 fuel respectively. The results also showed a considerable enhancement in brake thermal efficiency and heat release rate due to the influence of aluminium oxide nanoparticles addition in biodiesel–diesel blend.

Individual hydrocarbons and particulate matter emission from a turbocharged CRDI diesel engine fueled with n -butanol/diesel blends

The objectives of this study are to investigate the effect of a diesel fuel blend with n-butanol on the individual hydrocarbons and particulate matter (PM) of a turbocharged common rail direct injection diesel engine and to compare the results with the neat diesel fuel operation case. The emission characteristics were estimated by using 5%, 10%, and 20% (by volume) of n-butanol blended with conventional diesel fuel. The measured emissions were the regulated emissions of total hydrocarbons (HC) or individual HC, CO, NOx, PM and the non-regulated emission of formaldehyde, which were measured under three different engine loads (25.4, 52.9 and 78.4 N m) and three different engine speeds (1500, 2000 and 2500 rpm). It was found that more ethylene and benzene are emitted under low load condition, and that their amounts increase with increasing n-butanol blend ratio. The fuels blended with over 10% butanol produced higher non-regulated formaldehyde (HCHO) emission than the neat diesel fuel under lower engine load conditions. The particle numbers for particles smaller than 50 nm were higher for the fuel blended with 20% butanol in diesel fuel compared to the neat diesel fuel. From the TEM images, it was found that a larger number of individual particles with a size of 10–30 nm were stacked on top of each other in a circular pattern.

Diesel cold flow evaluation using design of experiment

It is very important to supply the diesel fuel from fuel tank to combustion chamber in case of cold start procedure. Paraffin hydrocarbons are easily solidified at low fuel temperature and it can block the fuel supply to the high pressure fuel pump. In order to reduce the fuel crystallization (Waxing), not only cold flow additives have been developed but also proper mounting design of fuel filter. Block heater in the fuel filter assembly have been also contained to improve the cold start and prevent blocking the fuel supply in Common Rail Direct Injection System. We need to make a test procedure of diesel cold flow evaluation to analyze the diesel cold flow characteristics. We can also obtain the design variables which have an effect to the diesel cold flow using the design of experiment and robust design. Finally the characteristics of diesel cold flow due to implementing cold flow evaluation test could be known.

Fuel characterisation, engine performance, combustion and exhaust emissions with a new renewable Licella biofuel

The current study investigates the opportunity of using Licella biofuel as a partly renewable fuel provided by Licella P/L. Hereafter this fuel will be referred to as Licella biofuel. The renewable component of the Licella biofuel was made from the hydrothermal conversion of Australian pinus radiata wood flour using Licella’s proprietary Cat-HTR™ technology. The diesel-soluble component of the hydrothermal product was extracted into road diesel to give a blended fuel containing approximately 30% renewable material with the balance from diesel. This was further blended with a regular diesel fuel (designated R0) to give fuels for testing containing 5%, 10% and 20% renewable fuel (designated R5, R10 and R20). Some of the key fuel properties were measured for R30 and compared with those of regular diesel fuel. The engine experiment was conducted on a four-cylinder turbocharged common rail direct injection diesel engine. All experiments were performed with a constant speed and five different engine loads. Exhaust emissions including particulate matter (PM) mass and numbers, nitric oxide (NO), total unburnt hydrocarbon (THC), carbon dioxide (CO2) and performance parameters including brake power (BP), indicated power (IP), brake mean effective pressure (BMEP), indicated mean effective pressure (IMEP), mechanical efficiency (ME), brake thermal efficiency (BTE) and brake specific energy consumption (BSEC) were investigated for all four blends (R0, R5, R10 and R20). Among other engine parameters, in-cylinder pressure, heat release rate (HRR) and pressure (P) versus volume (V) diagrams were also investigated for the four fuel blends.

Effect of diesel fuel blend with n-butanol on the emission of a turbocharged common rail direct injection diesel engine

Abstract The objectives of this study are to investigate the effect of diesel fuel blend with n-butanol on the emission of turbocharged common rail direct injection (CRDI) diesel engine and to compare the results with the neat diesel fuel operation case. The blends considered here were blends of diesel fuels with 10% and 20% (by volume) n-butanol. Engine performance and emission characteristics were measured by the European Stationary Cycle (ESC) test. Emissions of HCs, CO, NOx, HCHO, HCOOH and NH 3 were measured by Fourier Transform Infrared Spectroscopy (FTIR). Size and number distribution of particulate matter (PM) were measured by the Scanning Mobility Particle Sizer (SMPS). From the results, for the n-butanol blend, NOx emission increased compared with the neat diesel fuel case. At the case of 20% butanol, both THC and CO emissions increased significantly, and both HCHO and HCOOH increased modestly under the low loading of ESC 7, 9 and 11 mode compared with the neat diesel fuel case. Higher blending ratio (>20%) of butanol fuels could contribute to the precursor of PAHs formation such as toluene and benzene in diesel combustion. BU5 blend could be a better option to reduce the PM mass and the emissions of nanosized PM under 50 nm.

Performance evaluation of common rail direct injection (CRDI) engine fuelled with Uppage Oil Methyl Ester (UOME)

For economic and social development of any country energy is one of the most essential requirements. Continuously increasing price of crude petroleum fuels in the present days coupled with alarming emissions and stringent emission regulations has led to growing attention towards use of alternative fuels like vegetable oils, alcoholic and gaseous fuels for diesel engine applications. Use of such fuels can ease the burden on the economy by curtailing the fuel imports. Diesel engines are highly efficient and the main problems associated with them is their high smoke and NOx emissions. Hence there is an urgent need to promote the use of alternative fuels in place of high speed diesel (HSD) as substitute. India has a large agriculture base that can be used as a feed stock to obtain newer fuel which is renewable and sustainable. Accordingly Uppage oil methyl ester (UOME) biodiesel was selected as an alternative fuel. Use of biodiesels in diesel engines fitted with mechanical fuel injection systems has limitation on the injector opening pressure (300 bar). CRDI system can overcome this drawback by injecting fuel at very high pressures (1500-2500 bar) and is most suitable for biodiesel fuels which are high viscous. This paper presents the performance and emission characteristics of a CRDI diesel engine fuelled with UOME biodiesel at different injection timings and injection pressures. From the experimental evidence it was revealed that UOME biodiesel yielded overall better performance with reduced emissions at retarded injection timing of -10° BTDC in CRDI mode of engine operation.

Effect of fuel injection pressure and injection timing of Karanja biodiesel blends on fuel spray, engine performance, emissions and combustion characteristics

In this investigation, effect of 10%, 20% and 50% Karanja biodiesel blends on injection rate, atomization, engine performance, emissions and combustion characteristics of common rail direct injection (CRDI) type fuel injection system were evaluated in a single cylinder research engine at 300, 500, 750 and 1000bar fuel injection pressures at different start of injection timings and constant engine speed of 1500rpm. The duration of fuel injection slightly decreased with increasing blend ratio of biodiesel (Karanja Oil Methyl Ester: KOME) and significantly decreased with increasing fuel injection pressure. The injection rate profile and Sauter mean diameter (D32) of the fuel droplets are influenced by the injection pressure. Increasing fuel injection pressure generally improves the thermal efficiency of the test fuels. Sauter mean diameter (D32) and arithmetic mean diameter (D10) decreased with decreasing Karanja biodiesel content in the blend and significantly increased for higher blends due to relatively higher fuel density and viscosity. Maximum thermal efficiency was observed at the same injection timing for biodiesel blends and mineral diesel. Lower Karanja biodiesel blends (up to 20%) showed lower brake specific hydrocarbon (BSHC) and carbon monoxide (BSCO) emissions in comparison to mineral diesel. For lower Karanja biodiesel blends, combustion duration was shorter than mineral diesel however at higher fuel injection pressures, combustion duration of 50% blend was longer than mineral diesel. Up to 10% Karanja biodiesel blends in a CRDI engines improves brake thermal efficiency and reduces emissions, without any requirement of hardware changes or ECU recalibration.

Combustion Cycle-by-Cycle Variations in a Common Rail Direct Injection Engine Fueled with Dimethyl Carbonate–Diesel Blend

AbstractIn consideration of the multiple split injection, heavy exhaust gas recirculation (EGR) atmosphere, high latent heat of vaporization of dimethyl carbonate (DMC), and low cetane number, the combustion variations of both diesel and D10 (a fuel blend of 10% of DMC in diesel) have been investigated with characteristic parameters of indicated mean effective pressure pmi, peak pressure pmax, and initial 10% combustion duration θd. Results show that the cyclical coefficients of variation (COVs) of three characteristic parameters are lower than 2%. This means good combustion quality thanks to the precise control of fuel injection. The COVs for diesel are much smaller than those for D10 fuel. The COVs of pmi, pmax, and θd rise with a declining center of heat release (COHR), while the COVs show visible growth with the increase in EGR rate. The anticipation of possible combustion instability due to pilot injections did not happen. Both pmax and θd have good corresponding relations with pmi. The pmi positivel...

Effects of Canola Oil Biodiesel Fuel Blends on Combustion, Performance, and Emissions Reduction in a Common Rail Diesel Engine

In this study, we investigated the effects of canola oil biodiesel (BD) to improve combustion and exhaust emissions in a common rail direct injection (DI) diesel engine using BD fuel blended with diesel. Experiments were conducted with BD blend amounts of 10%, 20%, and 30% on a volume basis under various engine speeds. As the BD blend ratio increased, the combustion pressure and indicated mean effective pressure (IMEP) decreased slightly at the low engine speed of 1500 rpm, while they increased at the middle engine speed of 2500 rpm. The brake specific fuel consumption (BSFC) increased at all engine speeds while the carbon monoxide (CO) and particulate matter (PM) emissions were considerably reduced. On the other hand, the nitrogen oxide (NOx) emissions only increased slightly. When increasing the BD blend ratio at an engine speed of 2000 rpm with exhaust gas recirculation (EGR) rates of 0%, 10%, 20%, and 30%, the combustion pressure and IMEP tended to decrease. The CO and PM emissions decreased in proportion to the BD blend ratio. Also, the NOx emissions decreased considerably as the EGR rate increased whereas the BD blend ratio only slightly influenced the NOx emissions.

Combustion analysis of microalgae methyl ester in a common rail direct injection diesel engine

In this study, the biodiesel properties and effects of blends of oil methyl ester petroleum diesel on a CI direct injection diesel engine is investigated. Blends were obtained from the marine dinoflagellate Crypthecodinium cohnii and waste cooking oil. The experiment was conducted using a four-cylinder, turbo-charged common rail direct injection diesel engine at four loads (25%, 50%, 75% and 100%). Three blends (10%, 20% and 50%) of microalgae oil methyl ester and a 20% blend of waste cooking oil methyl ester were compared to petroleum diesel. To establish suitability of the fuels for a CI engine, the effects of the three microalgae fuel blends at different engine loads were assessed by measuring engine performance, i.e. mean effective pressure (IMEP), brake mean effective pressure (BMEP), in cylinder pressure, maximum pressure rise rate, brake-specific fuel consumption (BSFC), brake thermal efficiency (BTE), heat release rate and gaseous emissions (NO, NOx, and unburned hydrocarbons (UHC)). Results were then compared to engine performance characteristics for operation with a 20% waste cooking oil/petroleum diesel blend and petroleum diesel. In addition, physical and chemical properties of the fuels were measured. Use of microalgae methyl ester reduced the instantaneous cylinder pressure and engine output torque, when compared to that of petroleum diesel, by a maximum of 4.5% at 50% blend at full throttle. The lower calorific value of the microalgae oil methyl ester blends increased the BSFC, which ultimately reduced the BTE by up to 4% at higher loads. Minor reductions of IMEP and BMEP were recorded for both the microalgae and the waste cooking oil methyl ester blends at low loads, with a maximum of 7% reduction at 75% load compared to petroleum diesel. Furthermore, compared to petroleum diesel, gaseous emissions of NO and NOx, increased for operations with biodiesel blends. At full load, NO and NOx emissions increased by 22% when 50% microalgae blends were used. Petroleum diesel and a 20% blend of waste cooking oil methyl ester had emissions of UHC that were similar, but those of microalgae oil methyl ester/petroleum diesel blends were reduced by at least 50% for all blends and engine conditions. The tested microalgae methyl esters contain some long-chain, polyunsaturated fatty acid methyl esters (FAMEs) (C22:5 and C22:6) not commonly found in terrestrial-crop-derived biodiesels yet all fuel properties were satisfied or were very close to the ASTM 6751-12 and EN14214 standards. Therefore, C.cohnii- derived microalgae biodiesel/petroleum blends of up to 50% are projected to meet all fuel property standards and, engine performance and emission results from this study clearly show its suitability for regular use in diesel engines.

The effects of early inlet valve closing and cylinder disablement on fuel economy and emissions of a direct injection diesel engine

The influence of EIVC (early inlet valve closure) on emissions, fuel economy and exhaust gas temperature of a turbocharged, 4 cylinder common rail direct injection diesel engine has been investigated and compared with the influence of deactivating two cylinders. IVC (inlet valve closing) timings were set at up to 60 CA (crank angle) degrees earlier than the production setting of 37° ABDC for the engine. At the earliest timing, effective compression ratio was reduced from 15.2:1 to 13.7:1. The effects on emissions were significant only for EIVC settings at least 40 CA degrees earlier than the production setting, and were sensitive to engine load. At 2 bar BMEP (brake mean effective pressure) and fixed levels of NOx, soot emissions were reduced but CO (carbon monoxide) and HC (hydrocarbon) increased unless fuel rail pressure was reduced. With increasing load, soot reduction diminished and was negligible at 6 bar BMEP; CO and HC emissions deteriorated further. At all conditions, EIVC raised exhaust gas temperature by >50 °C; the effect on fuel economy was negligible or a fuel economy penalty. Comparisons indicate cylinder deactivation is the more effective strategy for reducing engine-out emissions of HC and CO and raising exhaust gas temperature under light load operating conditions.