Tech special: inside Jaguar Land Rover's new straight six engines-5/18/2019
Most recently it was Mercedes-Benz, now Jaguar Land Rover is switching back from a V6 to an inline six-cylinder petrol engine – the configuration once used by the likes of E-Type and XJS. The new 3.0-litre turbocharged unit, which features 48-volt mild-hybrid technology, makes its debut in the new Range Rover Sport HST (below), and replaces the previous 3.0-litre supercharged V6.
Effectively a four-cylinder with two extra cylinders, the new inline-six represents a logical extension – literally – of JLR’s modular four-cylinder aluminium Ingenium engines, introduced in 2015 and produced at the company’s Wolverhampton engine manufacturing plant. Benefits compared with a V6 include fewer parts – an inline-six has a single cylinder head, not two – economies of scale unlocked by sharing parts with the smaller Ingenium engines, and smoother power delivery.
The inline-six’s combination of 83mm bore and 92mm stroke is identical to four-cylinder Ingenium engines, and output is boosted by a twin-scroll turbocharger plus another compressor driven by an electric motor, which helps eliminate lag. Power peaks at 395bhp, torque at 406lb ft, where JLR’s beefiest supercharged V6 currently makes 375bhp/339lb ft in the F-Type.
Fuel efficiency is boosted by a 48-volt mild hybrid system. It harvests energy under braking, stores it in a battery, and can redeploy it, for instance when moving away after the stop-start system has killed the engine at the lights. Land Rover quotes 24.5-26.7mpg and 213g/km on the new WLTP test cycle.
The engine itself is 20kg lighter than the old V6, but that’s cancelled out by the extra weight of the mild-hybrid technology.
Other JLR models continue to use the V6 supercharged engine and turbodiesel V6s too, but inline Ingenium sixes are set to be phased in universally over time. Higher up the foodchain, BMW-sourced V8 bi-turbos will replace today’s Ford-sourced supercharged V8.