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NEW PLATFORM JAGUAR POWERTRAIN

2.0 l I4 turbocharged petrol engine is the lightest ever by Jaguar

3.0 l V6 supercharged engine offers the highest specific power output for a Jaguar engine

In an ongoing process to turn around its technical philosophy and offer newer and efficient technologies, Jaguar

announced two new powertrains at the Beijing Auto Show. Both engines are part of Jaguar’s strategy to expand

in emerging markets and bring in newer customers in the established regions. We bring to you a detailed insight

into the new engineering direction adopted by Jaguar in the area of forced induction, a popular norm today.

NEW JAGUAR ENGINES INNOVATINg New TreNds

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63autotechreview June 2012 Volume 1 I Issue 6

Jaguar’s two new petrol engines include a 3.0 l supercharged engine and a 2.0 l I4 turbocharged unit. In line with the global trend, both engines adopt downsizing and forced induction in order to increase power & torque and efficiency.

3.0 l V6 Supercharged (3.0l V6 S/C)

Unlike many OEMs, Jaguar has been con-sistently working on supercharging tech-nology for its bigger engines. The focus on this technology has been such that Jaguar is presently one of the leading players in the field of supercharging. A successful examples is the 5.0 l V8 engine used in the XKR-S, which produces about 542 hp and 680 Nm of torque.

The new engine is based on the same architecture as the 5.0 l unit and will be offered in two states of tune. The first option will produce 375 hp and 460 Nm of torque and will be used exclusively in the upcoming F-TYPE sports car. The other option will produce 335 hp and 450 Nm of torque and will serve as an option for the XF and XJ.

The specific power output of 125 hp per litre reflects Jaguar’s progress in supercharging technology. Both engines feature a higher specific output than the 5.0 l V8. A reason for this is the recalibra-tion of the electronic bypass of the super-charger and throttle leading to increased boost pressure without affecting the efficiency.

The new engine makes use of quad-cam technology, wherein the valves are controlled by a Dual Independent Variable Cam Timing (DIVCT) system. DIVCT’s activation is dependent on the positive and negative torque generated by the movement of the intake and exhaust valves. The system is capable of actuation rates surpassing 150° per second through the entire rev range. This results in better power delivery and fuel economy at all engine speeds.

Spray Guided Direct Injection (SGDI) further improves power delivery by deliv-ering the right quantity of fuel into the combustion chamber at pressures of up to 150 bar. The injection frequency is multi-ple within one combustion cycle, leading to a more uniform air-fuel mixture. The compression ratio has been increased

from 9.5:1 in the V8 to 10.5:1 in the V6.A Roots twin vortex supercharger is

located between the opposed cylinders. A new technology to feature in the engine is the supercharger boost control, which is electronically controlled by a new engine management software from Bosch. This technology alone is claimed to increase efficiency by up to 20 %. This engine will replace the naturally-aspirated 5.0 l V8 globally for the XF in 2013 and in most markets for XJ in the same timeframe.

2.0 l I4 240 Turbocharged petrol

The new four-cylinder 2.0 l engine will act as an extremely important engine to increase Jaguar’s footprint in emerging and new regions. The engine will deliver a maximum power output of 237 hp and 340 Nm of torque between 1,800 and 4,000 rpm. Along with a high power out-put, weight-reduction was of great impor-tance to the engineers. Owing to an all-aluminium construction and compact dimensions, this engine is Jaguar’s light-est ever at 138 kg.

The turbocharger on this engine is a low-inertia type, capable of delivering higher specific power and torque out-puts. In most cases, turbochargers need some time to reach optimum levels of operation and up till that stage, the emis-sions aren’t curbed effectively. Jaguar addressed this challenge by designing a lightweight and thin-walled exhaust manifold, which shortens the warm-up period and lowers emission.

The chain-driven variable timing is applied to the intake and exhaust valves, resulting in better spread of torque and improved bottom-end performance. Mini-mising friction is a proven method of increasing efficiency. Hence, the piston rings and tappets feature specialised coat-ings, designed to reduce friction. Fuel injection technology is the same as found in the V6 version.

With the engine slated to feature on cars projecting luxury as one of their USPs, low levels of NVH were a mandate. Towards this, the major additions are twin-balancer shafts, active engine mounts, acoustic engine cover and high-density foam. Addition of these technolo-gies ensures that addition of a turbo and downsizing of the engines does not affect

the NVH levels negatively. This engine will replace the 3.0 l AJV6 engine in most markets for the XF and XJ.

Both the engines will be combined with a ZF eight-speed automatic transmis-sion, further tuned by Jaguar. The trans-mission unit now features a wider spread of ratios than the standard unit, leading to easier usage of the engine power without affecting efficiency.

Outlook

Forced induction is one of the key tech-nologies that will be used by automakers to meet efficiency norms and satisfy con-sumer demand for engine performance. In recent times, carmakers have worked extensively on this technology due to its cost-effectiveness. The result of such focus has been the development of numerous assisting technologies, which have made it possible for a modern force-induced engine to surpass the out-put of similar engines from just about five years back.

Jaguar seems to be in favour of using supercharging and turbocharging to meet future efficiency-related norms, without giving up on its USP of making luxury sports cars. The new engines also high-light Jaguar’s focus on emerging markets.

For the next decade or so, an alterna-tive to forced-induction seems unlikely. It’s ease of installation and good results have made it popular among most of the carmakers. The basic architecture of a turbo and supercharger, however, hasn’t changed much since a long time and a scope for that seems to be quite slim. That said, the key differentiator among companies will be the effectiveness of their assisting technologies and that is where most companies will have to inno-vate. Jaguar seems to have done well in that area as the new engines feature almost every production-ready technology available presently.

TexT: Arpit Mahendra

PhOTO: Jaguar