Jags to stay super

Jaguar will retain supercharged engines in its next generation of vehicles. That’s the clear message from Jaguar insiders as the marque prepares to debut a new range of bespoke powerplants.

Jaguar will launch its new range of engines dubbed Ingenium (pictured) in its new mid-sized XE sedan later this year or early in 2015. Staring with four-cylinder powerplants, the new range was expected to be turbo-only.

Now, it seems that while turbos will be used for smaller displacement engines, the big-bangers under the hoods of both Jaguar and Land Rover models will stay supercharged.

Supercharged engines have been dropped by brands like Audi and Mercedes-Benz, because they were deemed to be too thirsty. But senior one Jaguar engineer told motoring.com.au the company continues to retain its penchant for the mechanically boosted system – at least in the case of its high-performance, large capacity petrol engines.

“When you look at smaller engines, 2.0 litres and below, then the supercharger [and its inherent] mechanical loses do become more significant than a turbocharger… But with bigger engines it’s less clear cut,” Tim Clark, Technical Specialist Performance and Driving Characteristics, told motoring.com.au at last week’s launch of the F-TYPE Coupe.

“Ultimately turbocharged engines are probably a little more economical, but you’ve got [issues such as turbo] lag and lack of response,” he opined.

Clark says Jaguar’s existing technology already sidesteps the major loses associated with supercharged engines. Applying this to the new modular architecture that’s expected to underpin the new Ingenium range of engines could deliver the best of both worlds.

“We have a very good [intake] bypass system. So while the supercharger isn’t clutched, all the time we can get everything we need from a naturally aspirated sense from the engine, you have a big electronically controlled bypass valve [in action].

So the supercharger is actually freewheeling until such time as you need the extra torque. Then we progressively close the bypass and the thing starts to generate boost. We can actually maximise the behaviour, the naturally aspirated torque of the engine, before we start loading the supercharger.”

Clark says the power delivery of a supercharged engine is a better match for Jaguar’s idea of how a sporting engine should behave.

“We think for bigger engines, it’s still a good attribute: plenty responsive, pretty good torque curve shape and plenty efficient.

“If anything, the thing you miss with a supercharged engine that you can get with a turbo is a complete plateau-flat torque curve. You can get max torque at 1500rpm [with a turbo] but in reality that doesn’t make a very good sportscar engine.

“What we like about the torque curve you get with supercharging is it actually just feels like a big naturally aspirated engine. Nice [progressive] growth of power and torque,” he stated.

Clark intimated the new smaller Jaguar engines would be turbo but in Jaguar’s engineering mindset supercharging had a long-term role to play.

“If you want to reuse the same technology on everything and you know everything there is to know about turbocharging, then for your smaller engines turbocharging is the best way to go for your CO2 [economy-focussed] kind of derivatives.

“Never say never. We may change [to turbos on large engines, or], we may not…

“At the moment direct-injection, twin variable cam timing and the latest generation superchargers -- it’s a pretty good package.”