Instant response. That's a measure of true performance. See the gap ahead. Pull out to pass. Step on the gas. The mark of a great engine is how quickly it can accelerate and get you past.
Consider this; Jaguar's brand-new 5-litre supercharged AJ-V8 Gen III R engine powering the 2010 model-year XKR and XFR, will thrust you from 50mph (80kph) to 70mph (113kph) in a blistering 1.9 seconds. Yes, 1.9 seconds.
"It's simply breathtaking. There's just an explosion of controllable power. It moves the Jaguar driving experience on to a whole new level," says Malcolm Sandford, Jaguar Engine Group chief engineer.
But instant response isn't reserved solely for Jaguar's new supercharged V8. A new line-up of ground-breaking 3-litre twin-turbocharged diesels offered in the 2010 XF delivers what is arguably an even more impressive number: idle to 500Nm (375 lb-ft) of torque in a staggering 500 milliseconds.
"What does that mean in real-world driving? It's when you're waiting at a junction and you see the gap in the traffic. Floor the throttle and you instantly get full engine torque. No lag. No hesitation. Instant response," explains Malcolm.
Mick Mohan, Jaguar Programmes director and the architect behind Jaguar's new technologies describes it best: "These new AJ-V8 and AJ-V6D Gen IIIs are simply the most technically advanced, most efficient engines Jaguar has ever produced."
The new petrol V8s are nothing less than a technical tour de force. Designed and developed by Jaguar's 800-strong powertrain team, they're new from the ground up and have only two components that are carried over from the previous 4.2. And these lightweight, compact, direct-injection engines bring significant improvements in both power and torque, but without compromising fuel economy or emissions.
"We set ourselves the challenge of developing an all-new V8 engine series that improved on the performance and refinement of the excellent 4.2-litre, with comparable fuel economy and improved emissions,” explains Ron Lee, Jaguar Powertrain Group chief engineer. “We have achieved that with the new AJ-V8 Gen III - a superbly responsive power unit of unsurpassed efficiency."
Two versions are on offer. The naturally aspirated 5-litre V8 produces 385PS and 515Nm (380 lb-ft) of torque - that's 26 and 23 per cent more respectively than its 4.2-litre predecessor.
The supercharged version, powering the new XFR saloon and XKR Coupé and Convertible, delivers a mighty 510PS and 625Nm (561 lb-ft) of torque – improvements of 23 and 12 per cent over the previous supercharged 4.2.
Take that to the road and the performance numbers become simply breathtaking. For example, the naturally aspirated XK's 0-60mph acceleration drops from 5.9 seconds to an impressive 5.2 seconds (0-100kph: 5.5 seconds). For the supercharged XKR, the 0-60mph sprint is covered in a searing 4.6 seconds (0-100kph: 4.8 seconds) – down from 4.9.
"This is the kind of awesome performance that will satisfy the most demanding drivers," says Mike Cross, Jaguar Vehicle Integrity chief engineer. "And thanks to intelligent use of advanced technologies, it comes with no reduction in fuel economy or increase in emissions."
The new AJ-V8s are built around a stiff, all-new aluminium cylinder block with cast-iron liners and cross-bolted main bearing caps to cut down on noise, vibration and harshness. The cylinder blocks are high pressure die-cast, providing a superior finish and greater dimensional accuracy. They use aluminium cylinder heads, with four valves for each cylinder, cast-iron crankshafts and forged-steel connecting rods.
One of the key features of these new petrol V8s is an industry-first, centrally mounted, multi-hole, spray-guided fuel injection system. This delivers fuel pressure of up to 150bar directly to the combustion chamber, contributing substantially to that low-speed, right-now, dynamic response.
They also feature a new, advanced type of variable camshaft timing system that's torque-activated (rather than by oil pressure), saving energy and reducing fuel consumption.
The XKR and XFR's 510PS V8 gets a new twin vortex system Eaton supercharger as well. It's a compact unit with a high-helix rotor design. That sounds complicated, but what it does is improve the supercharger's efficiency by some 16 per cent. A major benefit of this is that the supercharger unit is now almost inaudible, making that distinctive, piercing supercharger whine a thing of the past.
This has given the engineers the opportunity to invigorate the unique Jaguar engine sound that has become a hallmark of the XK and XF. For the 2010 versions they have deliberately boosted the acoustic feedback into the cabin, heightening the aural thrill of driving these cars. Both the XKR and XFR received special attention to ensure they delivered the required growling V8 intake sound character that's so often missing on supercharged engines. In the new system, intake manifold pressure pulsations are fed into an acoustic filter at the rear of the engine. Then, under specific conditions - such as when the car is accelerating hard - those pressure pulses are ducted into the cabin.
One sound you won't hear, at least so often, is that of the workings of the dealer service department. For all their performance and technical sophistication, both the normally aspirated and supercharged versions of the new 5-litre AJ-V8 Gen III engines offer extended service intervals - now 15,000 miles, rather than the previous 10,000 miles.
As equally groundbreaking as the new AJ-V8 petrol engines are the new high-performance, high-efficiency V6 diesels in the 2010 model-year XF: "These are the new benchmark, the new standard," explains Ron Lee. "They deliver superb flexibility with remarkably low fuel consumption and emissions while building on the refinement that has become a trademark of our Jaguar diesel engines."
Two versions of this new 3-litre AJ-V6D Gen III are on offer - a 240PS unit with 500Nm (396 lb-ft) and an ‘S' version with 275PS and 600Nm (443 lb-ft) of torque. Both deliver combined average fuel consumption of 42mpg - a 10 per cent improvement on the previous 2.7-litre – and have CO2 emissions of just 179g/km. And with this new engine, Jaguar has been able to meet tough upcoming EU5 emissions regulations well ahead of the 2011 legislative timetable.
But what really sets this new diesel apart is its remarkable low-speed throttle response. Much of this is down to the unique, parallel sequential turbocharger system - the first of its type to be fitted to a V-engine. These twin turbos work in sequence to deliver unrivalled response and best-in-class torque at low engine speeds, while packing a huge punch at higher engine speeds.
Alan Jones, diesel applications manager and the driving force behind Jaguar's diesel development team, explains that for most day-to-day driving, including motorway cruising, the bigger variable-geometry primary turbocharger does all the work. In the background is a smaller, fixed-geometry secondary turbo waiting to be called in.
"Accelerate hard and as the revs climb above 2800rpm, the secondary turbocharger is brought on line within just 300 milliseconds. There's no turbo-lag, or power-step. The transition is totally smooth, completely seamless."
Having the larger turbo as the primary also helps deliver truly exceptional low-speed response - as in summoning up 500Nm (369lb-ft) in only 500 milliseconds from idle. "This is truly a remarkable achievement,” adds Ron Lee. “The new parallel sequential turbocharger system on the V6 diesel delivers V8 levels of performance from very low revs."
It translates into impressive performance figures. The 275PS XF Diesel S can sprint from rest to 60mph in just 5.9 seconds (0-100kph: 6.4 seconds) and accelerate from 50mph (80kph) to 70mph (113kph) in a mere 3.2 seconds. And it won't stop accelerating until it reaches its governed top speed of 155mph (249kph). The 240PS version isn't far behind, reaching 60mph from zero in 6.7 seconds (0-100kph: 7.1 seconds), covering the 50-70mph dash in just 3.7 seconds and running hard to a 149mph (240kph) maximum.
Yet this remarkable performance is accompanied by a considerable reduction in CO2 emissions. In the XF, this new 3-litre AJ-V6D diesel produces 12 per cent less CO2 than the previous 2.7-litre, while in the Diesel S version, power has increased by a hefty 33 per cent. And in both versions of the new diesel, the combined average fuel consumption is 42mpg, which represents an improvement of more than 10 per cent on the 2.7.
Reduced noise, quieter running, faster warm-up from start and extended service intervals – now 16,000 miles – are other improvements that make these new Jaguar diesels world class.
"Our mission from the outset when developing these new technically advanced V8 petrol and V6 diesel engines was to deliver instant response," says Malcolm Sandford of the powerful technology at the heart of the 2010 XKR and XFR.
"We're confident the response we'll get from customers when they get behind the wheel is 'Mission accomplished'."
[Issue 1, 2009]