Attention: TDR Forum Junkies 
This note gives the flavour of the way it is in Europe and indicates their different position.
Diesel genes
Commercial pressure and massively improved technology topple another ivory tower as Jaguar finally delivers a diesel. Matt Youson reports
It’s interesting what a little digging around in the archive throws up. In the summer of 1999 Jaguar opened a huge extension to its engine test centre at the company’s Whitley Engineering Centre in Coventry. Interviewing some of Jaguar’s most senior engine development engineers after a tour of the new test cells, the transcript shows that engineering, noting that the new cells all had a multi-fuel infrastructure, asked if Jaguar were considering the introduction of a diesel variant. “There will never be Jaguar with a diesel engine,” was the reply, firmly ending that line of enquiry.
How times change. Jaguar chose to kit out their new engine and full chassis dynamometers with an infrastructure for diesel (and for that matter several other alternatives to gasoline) purely for benchmarking purposes: like any other manufacturer, not all of the engines on Jaguar’s test beds are of the in-house variety. But it doesn’t take results from a test cell to work out that Jaguar’s long-standing single-minded devotion to petrol was letting the company down badly.
The advances made in diesel technology over recent years have seen the numbers of steadfast sparkophiles in the automotive industry dwindle almost to nothing. Since 1999 Alfa Romeo, Saab and latterly Honda have all accepted the inevitable and
introduced diesel. Jaguar held out longest and as late as the Paris Motor Show in September 2002, officials were still denying that an oil burner was definitely on the agenda. By that stage such a statement was taken with a pinch of salt, since the turn of the Century rumours had appeared with monotonous regularity telling of Jaguar’s intention to source engines from BMW or DaimlerChrysler or VW, or to share development with PAG stable mate Volvo. When official news of a deal to procure engines from the Ford/PSA partnership finally broke, surprise was noted only by its absence.
Bespoke
Two projects have been announced. A bespoke V6 unit will go into production at Ford’s Dagenham plant but more immediately a smaller four cylinder unit will appear on the MY2004 Jaguar X-Type, expected to go on sale in September. The 2. 0D engine, codenamed X404, is a derivation of Ford’s 2. 0 litre TDCi diesel engine as used in the X-Type’s sister vehicle, the Ford Mondeo.
With a capacity of 1,998cc, from classically ‘square’ bore and stroke dimensions of 86x86mm, the engine features a very stiff cast-iron block with aluminium ladder frame. An aluminium alloy cylinder head with a separate aluminium alloy camshaft carrier assembly also features, as do double overhead camshafts driven by a duplex chain that also drives the high-pressure fuel-injection pump. The camshafts operate four valves per cylinder (two inlet and two exhaust), through large diameter roller rockers designed for low friction and long life. Each camshaft is a fabricated component with sintered cam lobes - again for long life.
Lightweight
The crankshaft is forged steel, with five main bearings. It uses eight counterweights (two per cylinder). Lightweight aluminium alloy pistons give high performance, and sinter-forged connecting rods use fracture-split big-end journals for lightweight and precision fit. The fuel system combines very high-pressure common-rail direct injection with a variable-geometry turbocharger and a charge-air intercooler. This has been developed in Jaguar’s adaptation of this engine and adds instant throttle response to the engine’s appeal.
An engine-driven, dual-stage vane-cell type fuel pump draws diesel from the tank, via a fuel filter. It delivers the diesel at very high pressure to the rail, which supplies the individual injectors. The common-rail is capable of withstanding pressures in excess of 3,000bar with four outlets, each feeding a separate fuel injector nozzle. For the X-Type X404 engine, Jaguar chose a ‘short-nozzle’ head design and new short-nozzle injectors that make the engine quieter and improve refinement.
The electronically controlled short-nozzle injectors can each deliver two precisely metered shots of fuel on each power stroke - a pilot injection and a main injection. The very small volume pilot injection comes earlier in the stroke, followed by the bigger volume of the main injection, which produces the power. The ultra-fine fuel vaporisation, two-phase injection and precise metering and timing, together have the effect of making the combustion process more progressive and more efficient. This means the engine runs more smoothly, is quieter, and delivers more power for less fuel. This efficiency is achieved at all engine speeds: at idle, noise levels are reduced by the ECM adjusting the pilot injection; at higher speeds, torque and power output are increased by extending the main injection to give a longer fuel-burn duration.
The ‘brain’ of the system, the ECM, controls both the diesel pump and the injectors. It takes information from sensors that monitor crankshaft, camshaft and throttle positions, and uses this data to assess engine speed, load and other factors. From there, for every single power stroke of each individual cylinder, the ECM computes the unique injection profile that will deliver optimum engine performance, and varies the rail pressure, the fuel volume and the injection timing to deliver it. In practice the injection pressure ranges from 230bar at low engine speeds to 1,500bar when engine speed exceeds 2,000rev/min.
Refinement
Beyond this technology, the Jaguar diesel engine has several additional features that optimise efficiency and maximise refinement. The first is a new system for detecting and reducing combustion noise. The combustion noise sensor records each stroke in each cylinder, and by fine adjustments to the pilot and main injectors every 0. 3ms ensures the X404 is exceptionally quiet. It is also a ‘learning’ system, whose effectiveness increases as it operates. It calculates the minimum drive pulse (MDP) needed to provide the required output with the lowest combustion noise, especially at idle speeds. During assembly, the ECM system is programmed with an approximate value for the MDP. Every time the engine runs thereafter, the ECM continuously updates the MDP settings according to road- and other conditions.
A further refinement in the X404 engine involves the way the individual fuel injectors are constructed to produce optimum performance as an assembly. Although they are manufactured with a very high degree of precision, the manufacturing tolerances involved are so minute that each injector has its own, unique ‘fingerprint’. These fingerprints are crucial to the way the ECM controls each injection parameter, in order to maintain the engine’s smooth running, low noise and optimum performance.
During manufacture, every injector is calibrated and its characteristics are written into a barcode label that is attached to the individual injector. As each engine is assembled, four injectors are selected at random. Their barcodes are scanned, and a new ‘composite’ barcode is generated, incorporating the collective data from the separate components of the injector set. That composite barcode (which by definition is itself unique) is attached to the engine. When the engine and ECM come together in the vehicle, the data from the composite barcode is transferred to the ECM - so that every ECM is perfectly tailored, individually, to its own injector set.
Pilot light
Whether the preferred option is unit-Injector or common-rail-based, injector technology was key to the rehabilitation of diesel engines in the 1990s, but the technology has not stood still – witness, for example, Bosch’s 3rd generation common-rail system, which went into series production in May. In Bosch’s conventional common-rail system the injector is controlled by a magnetic coil and a piston rod transmits the hydraulic force required to open or close the injector to the nozzle needle. In the new system the injector actuators consist of piezo crystals. Piezo crystals have the property of expanding in an electrical field. For the piezoelectric actuator, Bosch engineers use a package of several hundred very small, thin crystals. The piezo actuator switches in less than ten thousandths of a second (less than half the time required by a magnetic switch).
To exploit this property, Bosch has integrated the actuator into the injector body. In the inline injector, the movement of the piezo package is transferred to the rapid-switch nozzle needle without friction: there are no mechanical components. The advantages over magnetic and existing conventional piezo injectors lie in a more precise dosing and an improved atomisation of the injected fuel mixture within the combustion chamber. The higher switching speed of the injector means that the intervals between the individual fuel injections can be reduced, giving a more flexible control of the injection process. The result is that diesel engines become even quieter, more fuel efficient, cleaner and more powerful. With the inline injector, the return flow of fuel not required for injection is very small. This allowed Bosch’s engineers to further reduce the delivery rate and thus the energy requirement of the high-pressure pump.
The low tolerances for the injection quantity and timing mean that the fuel dosage at the injector is very exact. This results in lower levels of exhaust pollutants. For example, one or two pre-injections of fuel prevent the emission of white and blue smoke just after a cold start and combustion noise is reduced. A supplementary injection following immediately on the main injection lowers the emission of soot particulates and a further injection can regenerate particulate filters.
Diesel genes
Commercial pressure and massively improved technology topple another ivory tower as Jaguar finally delivers a diesel. Matt Youson reports
It’s interesting what a little digging around in the archive throws up. In the summer of 1999 Jaguar opened a huge extension to its engine test centre at the company’s Whitley Engineering Centre in Coventry. Interviewing some of Jaguar’s most senior engine development engineers after a tour of the new test cells, the transcript shows that engineering, noting that the new cells all had a multi-fuel infrastructure, asked if Jaguar were considering the introduction of a diesel variant. “There will never be Jaguar with a diesel engine,” was the reply, firmly ending that line of enquiry.
How times change. Jaguar chose to kit out their new engine and full chassis dynamometers with an infrastructure for diesel (and for that matter several other alternatives to gasoline) purely for benchmarking purposes: like any other manufacturer, not all of the engines on Jaguar’s test beds are of the in-house variety. But it doesn’t take results from a test cell to work out that Jaguar’s long-standing single-minded devotion to petrol was letting the company down badly.
The advances made in diesel technology over recent years have seen the numbers of steadfast sparkophiles in the automotive industry dwindle almost to nothing. Since 1999 Alfa Romeo, Saab and latterly Honda have all accepted the inevitable and
introduced diesel. Jaguar held out longest and as late as the Paris Motor Show in September 2002, officials were still denying that an oil burner was definitely on the agenda. By that stage such a statement was taken with a pinch of salt, since the turn of the Century rumours had appeared with monotonous regularity telling of Jaguar’s intention to source engines from BMW or DaimlerChrysler or VW, or to share development with PAG stable mate Volvo. When official news of a deal to procure engines from the Ford/PSA partnership finally broke, surprise was noted only by its absence.
Bespoke
Two projects have been announced. A bespoke V6 unit will go into production at Ford’s Dagenham plant but more immediately a smaller four cylinder unit will appear on the MY2004 Jaguar X-Type, expected to go on sale in September. The 2. 0D engine, codenamed X404, is a derivation of Ford’s 2. 0 litre TDCi diesel engine as used in the X-Type’s sister vehicle, the Ford Mondeo.
With a capacity of 1,998cc, from classically ‘square’ bore and stroke dimensions of 86x86mm, the engine features a very stiff cast-iron block with aluminium ladder frame. An aluminium alloy cylinder head with a separate aluminium alloy camshaft carrier assembly also features, as do double overhead camshafts driven by a duplex chain that also drives the high-pressure fuel-injection pump. The camshafts operate four valves per cylinder (two inlet and two exhaust), through large diameter roller rockers designed for low friction and long life. Each camshaft is a fabricated component with sintered cam lobes - again for long life.
Lightweight
The crankshaft is forged steel, with five main bearings. It uses eight counterweights (two per cylinder). Lightweight aluminium alloy pistons give high performance, and sinter-forged connecting rods use fracture-split big-end journals for lightweight and precision fit. The fuel system combines very high-pressure common-rail direct injection with a variable-geometry turbocharger and a charge-air intercooler. This has been developed in Jaguar’s adaptation of this engine and adds instant throttle response to the engine’s appeal.
An engine-driven, dual-stage vane-cell type fuel pump draws diesel from the tank, via a fuel filter. It delivers the diesel at very high pressure to the rail, which supplies the individual injectors. The common-rail is capable of withstanding pressures in excess of 3,000bar with four outlets, each feeding a separate fuel injector nozzle. For the X-Type X404 engine, Jaguar chose a ‘short-nozzle’ head design and new short-nozzle injectors that make the engine quieter and improve refinement.
The electronically controlled short-nozzle injectors can each deliver two precisely metered shots of fuel on each power stroke - a pilot injection and a main injection. The very small volume pilot injection comes earlier in the stroke, followed by the bigger volume of the main injection, which produces the power. The ultra-fine fuel vaporisation, two-phase injection and precise metering and timing, together have the effect of making the combustion process more progressive and more efficient. This means the engine runs more smoothly, is quieter, and delivers more power for less fuel. This efficiency is achieved at all engine speeds: at idle, noise levels are reduced by the ECM adjusting the pilot injection; at higher speeds, torque and power output are increased by extending the main injection to give a longer fuel-burn duration.
The ‘brain’ of the system, the ECM, controls both the diesel pump and the injectors. It takes information from sensors that monitor crankshaft, camshaft and throttle positions, and uses this data to assess engine speed, load and other factors. From there, for every single power stroke of each individual cylinder, the ECM computes the unique injection profile that will deliver optimum engine performance, and varies the rail pressure, the fuel volume and the injection timing to deliver it. In practice the injection pressure ranges from 230bar at low engine speeds to 1,500bar when engine speed exceeds 2,000rev/min.
Refinement
Beyond this technology, the Jaguar diesel engine has several additional features that optimise efficiency and maximise refinement. The first is a new system for detecting and reducing combustion noise. The combustion noise sensor records each stroke in each cylinder, and by fine adjustments to the pilot and main injectors every 0. 3ms ensures the X404 is exceptionally quiet. It is also a ‘learning’ system, whose effectiveness increases as it operates. It calculates the minimum drive pulse (MDP) needed to provide the required output with the lowest combustion noise, especially at idle speeds. During assembly, the ECM system is programmed with an approximate value for the MDP. Every time the engine runs thereafter, the ECM continuously updates the MDP settings according to road- and other conditions.
A further refinement in the X404 engine involves the way the individual fuel injectors are constructed to produce optimum performance as an assembly. Although they are manufactured with a very high degree of precision, the manufacturing tolerances involved are so minute that each injector has its own, unique ‘fingerprint’. These fingerprints are crucial to the way the ECM controls each injection parameter, in order to maintain the engine’s smooth running, low noise and optimum performance.
During manufacture, every injector is calibrated and its characteristics are written into a barcode label that is attached to the individual injector. As each engine is assembled, four injectors are selected at random. Their barcodes are scanned, and a new ‘composite’ barcode is generated, incorporating the collective data from the separate components of the injector set. That composite barcode (which by definition is itself unique) is attached to the engine. When the engine and ECM come together in the vehicle, the data from the composite barcode is transferred to the ECM - so that every ECM is perfectly tailored, individually, to its own injector set.
Pilot light
Whether the preferred option is unit-Injector or common-rail-based, injector technology was key to the rehabilitation of diesel engines in the 1990s, but the technology has not stood still – witness, for example, Bosch’s 3rd generation common-rail system, which went into series production in May. In Bosch’s conventional common-rail system the injector is controlled by a magnetic coil and a piston rod transmits the hydraulic force required to open or close the injector to the nozzle needle. In the new system the injector actuators consist of piezo crystals. Piezo crystals have the property of expanding in an electrical field. For the piezoelectric actuator, Bosch engineers use a package of several hundred very small, thin crystals. The piezo actuator switches in less than ten thousandths of a second (less than half the time required by a magnetic switch).
To exploit this property, Bosch has integrated the actuator into the injector body. In the inline injector, the movement of the piezo package is transferred to the rapid-switch nozzle needle without friction: there are no mechanical components. The advantages over magnetic and existing conventional piezo injectors lie in a more precise dosing and an improved atomisation of the injected fuel mixture within the combustion chamber. The higher switching speed of the injector means that the intervals between the individual fuel injections can be reduced, giving a more flexible control of the injection process. The result is that diesel engines become even quieter, more fuel efficient, cleaner and more powerful. With the inline injector, the return flow of fuel not required for injection is very small. This allowed Bosch’s engineers to further reduce the delivery rate and thus the energy requirement of the high-pressure pump.
The low tolerances for the injection quantity and timing mean that the fuel dosage at the injector is very exact. This results in lower levels of exhaust pollutants. For example, one or two pre-injections of fuel prevent the emission of white and blue smoke just after a cold start and combustion noise is reduced. A supplementary injection following immediately on the main injection lowers the emission of soot particulates and a further injection can regenerate particulate filters.
