All-New Jaguar XJ

TURBOCHARGERS

The new AJ-V6D Gen III engine's superb dynamic response is ensured thanks to its unique, parallel sequential turbocharger system; the first of its type to be fitted to a V-engine. Delivering high torque, improved throttle response and low CO2 emissions, the twin-turbos work sequentially to deliver best-in-class torque at low engine speeds, while packing a huge punch at higher revs.

TURBOCHARGER SYSTEM PHASE ONE

For most day-to-day driving, a responsive, variable-geometry primary turbocharger (shown bottom left in animation) does all the work while the smaller, fixed-geometry, secondary turbo (bottom right in animation) is dormant, saving energy and improving efficiency.

Driving a turbocharger requires pressure from the exhaust, creating engine pumping losses and increased fuel consumption. To alleviate this, valves isolate the secondary turbo from the exhaust stream and the engine inlet tract when it is not required.

TURBOCHARGER SYSTEM PHASE TWO

When the engine revs climb above 2800rpm (click 'NEXT' on animation to illustrate), the secondary turbo is brought up to speed ('Transient Phase'), before further valves open to bring the turbo fully online within 300 milliseconds (click 'NEXT'), boosting the engine output with no discernible turbo-lag. Some twin-turbo systems rely on the smaller turbo for primary use, only using a larger turbo when higher power is required. This has the disadvantage of raised exhaust pressure and increased pumping losses.

The Jaguar system uses its larger 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. The new AJ-V6D Gen III 3.0-litre diesel significantly out-performs its rivals by delivering 500Nm of torque in only 500 milliseconds from idle.

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TURBOCHARGER OPERATION

PHASE ONE: SINGLE TURBOCHARGER MODE

TRANSIENT PHASE

PHASE TWO: TWIN TURBOCHARGER MODE

AIR

CHARGED AIR

EXHAUST GAS

COOL CHARGED AIR