More Economy And Power From Jaguar’s New Diesel

More Economy And Power From Jaguar’s New Diesel

January 2009

Jaguar has announced two versions of a new three litre V6 turbo diesel engine to power its award winning XF sports sedan.

The more powerful of the 2010 model year cars will be badged the Jaguar XF Diesel S and produce 202 kWs and pack no less than 600 Nm of torque.

Click to enlarge

The other three litre model will have 177 kWs and 500 Nm, compared to the current 2.7 litre XF Turbo Diesel’s 152 kWs and 435 Nm.

The new engine is the most advanced, powerful and efficient Jaguar diesel ever produced and will accelerate the XF Diesel S to 60 mph in just
5.9 seconds and have an electronically controlled top speed of 250 km/h.

Yet its combined fuel economy of just 6.8 litres/100 kilometres is 12 percent better than the current acclaimed 2.7-litre V6 diesel engine. And it emits just 179g/km – a 10 percent reduction in CO2, while conforming to the more stringent EU5 emission regulations.

The three litre “S” engine is 33 percent more powerful and has 61 percent more torque from 1500rpm than the 2.7-litre V6 diesel.

“With CO2 emissions of 179g/km, average fuel economy under 7 litres/ 100 kms and almost supercar acceleration times, this is another great example of Jaguar delivering unrivalled performance while at the same time taking the level of refinement in diesel engines to a whole new level,” said Wallis Dumper, the managing director of Jaguar New Zealand.

When it was introduced last year, the XF was recognised as a dramatic expression of a bold new Jaguar design language. It also soon became apparent that here was a car where the driving experience exceeded the expectations created by the striking appearance. Now, the new XF Diesel S takes this driving experience to new levels, shifting the balance even further towards dynamic performance while still retaining the XF’s core values as a refined and luxurious sports saloon.

Featuring parallel sequential turbochargers to help deliver the high levels of power and torque seamlessly and with effortless flexibility, the engine is perfectly matched to Jaguar’s sophisticated six-speed ZF 6HP28 automatic transmission.

“The new parallel sequential turbocharger system on our new V6 diesel delivers V8 levels of performance from very low revs. It’s a power unit that offers superb flexibility and remarkably low fuel consumption and emissions, while building on the refinement that has become a trademark of our Jaguar diesel engines,” said Ron Lee Jaguar’s Chief Engineer, Power-train.

There will be an equally impressive 177 KWs version of the new 3.0-litre engine available too, which produces 16 percent more power and a 15 percent increase in torque over the 2.7-litre diesel, allowing the “standard” three litre XF Diesel to reach 60 mph in 6.7 seconds. Like the “S” engine, these performance leaps are achieved with combined average fuel consumption of 6.8 litres/100 kilometres and a CO2 emissions rating of only 179g/km.

The acclaimed XF 2.7 Diesel has won accolades, worldwide and closer to home, including the NBR Car of the Year, NZ Company Vehicle Executive Car of the Year and NZ Autocar’s Luxury Car of the Year.

The new three litre Jaguar XF Turbo Diesel models will be available in New Zealand in the third quarter of the year.

Technical Details

A key feature of the new three litre engine is the unique, parallel sequential turbocharger system, the first of its type to be fitted to a V-engine anywhere in the world.

Delivering high torque throughout the entire engine rev range, improved throttle response and low CO2 emissions, the twin-turbochargers work sequentially to deliver unrivalled response and best-in-class torque – while packing a huge punch at higher engine speeds.

For most day-to-day driving, including motorway cruising, a responsive, variable-geometry primary turbocharger does all the work, while the smaller, fixed-geometry, secondary turbo is dormant, saving energy and improving efficiency. When the engine revs climb above 2800rpm, the secondary turbo is brought on line within 300 milliseconds, smoothly and seamlessly boosting the engine output with no discernible turbo-lag or power-step.

Driving a turbocharger requires pressure from the exhaust, creating pumping losses in the engine and increasing fuel consumption. To alleviate this, valves under the control of the engine management system isolate the secondary turbocharger both from the exhaust stream and the engine inlet tract when it is not required.

Some twin-turbo systems rely on a smaller turbo for primary use, only using a larger turbo when higher power is required. Though effective, this has the disadvantage of raised exhaust pressure and increased pumping losses. The Jaguar system uses a larger, variable-geometry turbocharger more of the time, which not only reduces pumping losses, but also improves fuel consumption and CO2 emissions.

Jaguar engineers particularly focussed on the issue of turbocharger ‘lag’ at low engine speeds. Both new AJ-V6D Gen III 3.0-litre diesels significantly out-perform their rivals by delivering 500Nm of torque in only 500 milliseconds from idle.

A new common rail fuel-injection system delivers up to five injections on each cycle at a pressure of 2000bar. Each injector tip is perforated by seven holes through which finely atomised fuel is sprayed into the cylinders. The high-pressure injection increases power, improves economy and reduces both CO2 and particulate emissions.

Piezo crystal ‘packs’ operate each injector by expanding when an electric current is passed through them. They react virtually instantaneously but can make a distinctive click when fired, which can add to diesel engine noise at idle. The crystals in Jaguar’s new injectors are fitted nearer the tip, meaning they are mounted deeper inside the engine providing better sound insulation and quieter operation.

Another new feature of the third-generation fuel-injection system is the metering mode. Traditional diesel common rail fuel pumps oversupply the injectors, with the surplus being returned to the fuel tank. During this process, fuel temperature increases and cooling it again consumes considerable amounts of energy. In metering mode, the pump delivers fuel to the injectors only at the rate required. Consequentially, there is no rise in fuel temperature and no wasted energy.

The two cylinder heads, with four valves per cylinder, are made from aluminium and the cylinder block is made from compact graphite iron (CGI). The higher tensile strength of CGI makes it possible to cast a smaller block; some 80mm shorter than a conventional ‘grey’ cast iron equivalent.

The new, water-cooled, exhaust gas recirculation system (EGR), important for reducing pumping losses and emissions of NOX in a diesel engine, is more efficient and consumes less power than the 2.7-litre unit. The valves that allow exhaust gas into the system are located on the ‘hot side’ of the engine nearest the exhaust manifolds; these valves never cool while the engine is running, so there is no condensation of combustion deposits which occurs on engines fitted with ‘cold side’ valves, hence the EGR system always works at maximum efficiency. Since the EGR cooling is so effective, exhaust gasses can bypass the system and return to the exhaust pipes, allowing faster engine warm-up from start-up and reducing emissions still further.

EU5 emissions regulations have been achieved ahead of the 2011 legislative timetable using conventional diesel oxidation catalysts and diesel particulate filters (DPFs). NOX levels are reduced at source through the combustion system design, the addition of the new common rail injection system and the new EGR system with by-pass. As a result, specialised NOX exhaust after-treatment is unnecessary, avoiding a potential cost and the need to use additional precious metals in the exhaust system.

The CGI cylinder block and new piezo injectors reduce combustion noise in the engine. Multiple, precise injections of fuel on the combustion stroke also reduce combustion noise and all engine covers including camshaft covers, front covers and the sump have been optimised to subdue radiated noise. Engine enclosures have been ribbed to minimise radiated noise and the sump pan is manufactured from sound deadening steel (SDS), comprising a polymer layer sandwiched between two layers of steel.

Internal friction, a major contributor to unnecessary fuel consumption, has been addressed by careful optimisation of the crankshaft, valves and pistons. All these features combine to make the new Jaguar AJ-V6D Gen III engines amongst the quietest premium diesels on the market.

With its parallel sequential turbocharger system, third-generation common rail fuel injection system and fully optimised EGR system, the new 3.0-litre AJ-V6D Gen III diesel sets new class standards when it comes to power, response and refinement in the premium diesel segment.

“The new XF challenges the rules and redefines Jaguar sporting luxury. Our designers and engineers have worked together to develop elegant, inspired solutions to complex technical challenges. It’s a simple but very effective philosophy and the result is great new products like the new 3.0-litre diesel XF,” said
Mike O’Driscoll, Managing Director, Jaguar Cars

ENDS

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