Jagtoes mention his interest in starting a thread on this subject so here it is ...

Any comments on drivability and durability are welcome

 

I know I may be pushing it a bit but to bad we couldn't get data from the other Jag/LR cars who use the same engines. Hey , good enough and lets see what comes out of this. Thanks

 

My SC 4.2's been a nightmare up to 50k miles. Guzzles a tank of gas in only 320 miles. Keep having to change the oil every 10k miles. Boring! I never get to drool over the new Jag's at the dealership while waiting in the service department. Totally missing out on the driving experience of the Jag's of yore. If that's what you're looking for don't buy this car. Didn't even come with a tool kit.

 

I have a 2009 XKR Portfolio Edition Convert with the 4.2L Supercharged engine.
This XKR has more power than I would ever need on USA roads and highways.

The acceleration is enormous and will snap your head back. The 4.2L has been flawless. Of course, I only have 17,300 miles on this beautiful XKR.

Over the 3 1/2 years of ownership, I completed 2 oil changes, not due to mileage but the age of the oil. I replace the oil annually with new filter regardless of miles driven.

Since ownership of the last 3 1/2 years my total cost for maintenance has been under $200 which was the first oil change at $135.00 from the local Jaguar dealer, and the second oil change at $65.00 from an independent shop. . I have not dropped any other funds/money into the car for the maintenance. The XKR runs, starts and performs flawlessly.

I am sure more members own the 5.0L engine due to the newer model years, but I have read repeatedly of problems with fuel/water pumps etc.

Click the thumbnail to expand the image, and once again for full screen.

 

I currently drive both, as indicated in my signature - a 2009 4.2L SC XKR (420HP) and a 2013 5.0L SC XJ (470HP). The 4.2 has all the power any sane person needs on the street, and the 5.0 is a bit of overkill but Woohoo!

From a driveability standpoint, the 5.0 wins; no contest - its massive torque curve is always there, particularly at the low end, ready and waiting to make the big cat leap ahead. The 4.2 simply doesn't feel as strong. Other improvements (8-speed vs.6-speed and Dynamic Mode in the XJ) also contribute to its superior driveability.

From a reliability standpoint, the 4.2 had the thermostat replaced under warranty and the 5.0 had the water pump replaced under warranty.

I do mostly city driving. Surprisingly, I get over 16 MPG in the 5.0 but only 13 MPG in the 4.2. I probably rev the 4.2 higher to hear that glorious exhaust note. And the 5.0 has Stop-Start, which helps the city MPG.

Stuart

 

Fantastic write up Stuart

Yes your right the 4.2 definitely do drink a lot more due to the fact of more revs are required to get it going as opposed to the 5.0 needed fewer ...that glorious torque curve !!

In your option and I know you won't be bias considering the fact you have both engines which sound do you prefer

 

The XJ is a gentleman's 4-door sedan, replete with magnificent burl wood veneer, fantastic Meridian Surround Sound and a quiet cabin. It exudes elegance and, as such, a rowdy exhaust note would be out of character. Nevertheless, with the windows up and the stereo off there is still a noticeable and very pleasing low gurgle under moderate acceleration, which gets a bit louder the more you step on the exhilarator pedal. I think the factory got it right for the XJ.

Similarly, the XKR is a gentleman's sporting car, and mine has the classic wood veneer with every creature comfort. The factory dual-mode exhaust gives it a Jekyll and Hyde personality, but I prefer the sweet sound in rowdy mode so I removed fuse 19. Just loud enough to not upset my neighbors.

Different sounds for different vehicles, but just right for my tastes. Love them both.

 

S/C 5.0 with nearly 60,000 miles, almost five years and not even one hiccup, excluding a recent once-in-awhile adaptive headlight dash light where I tap the headlight and it goes away for another couple months. Oh, and one new TPMS sensor. No weird sounds, no squirrelly behavior. The only ACTUAL problem I've had was with the junk Michelins. Not my car's fault.

 

In Enzo Ferrari's words 'You buy the engine and you get the car for free'
The 5.0 is such, its total satisfaction, doesn't not have me looking for power by mods. Love love love the low-end response, its a supercar in this regard. In city driving and low speeds, you get the pin down of full torque.

 

Your right queen & country it's the torque that makes a vehicle a pleasure to drive

 

Got my '07 two years ago with just under 30k miles, now it's over 40. Replaced battery and brake pads then the thermostat (just because) and changed the oil a few times. Rear tires will go soon.
As another member in the area pointed out, I live in a area where the straight roads have curves, unless I drive down to Atlanta. It's just plain fun to drive and has spent a LOT less time in the shop that my 911 did.

 

I've got the 4.2 in the NA version with the XKR rear box on it. The engine and drive train have been solid for the year that I've owned the car. It's quick enough for my driving style, though my next XK will be an XKR just for S&G's.

 

Few get that in USA. And because its the largest market, they dictate car design for much of the world. So an xkr that has no equal unless you spend 3times the price, is entirely underappreciated.

I have had Porches, none of them have authority, they require a gear change and jump in rpm to overtake- the Jag does it while trotting. Only two other cars I have driven did that, RR Phantom and old big block Trans-am. imo, the gear change drama distracts from the 'sit back and enjoy' g-force of acceleration.

 

Wow Im quite surprised at the number of n/a 4.2 on this forum I honestly thought the 4.2 s/c would dominate the polls

 

I guess I am also surprised that we only have 29 active members participating. Somehow I don't think this few bits of data would establish to much creditable reliability data. For any numbers folks what is a usable number to establish trends. Somehow I was assuming maybe 50-100 voting.

 

For the record, my 07 normally aspirated 4.2 has been 100 per cent trouble free and the only time it has been in the dealer's shop was for the normal yearly oil changes. I have to say that this engine is a glorious bit of machinery (without the potentially troublesome supercharger) and is plenty fast in any circumstance. Having the extra power of the supercharged version (especially the 5.0 litre - which I have driven) might be fun in theory but I found it a bit squirrelly under full acceleration. In the hands of an irresponsible person any of the XKs, 4.2 or 5 litre, could be dangerously fast. But the exhaust note, the shape, the handling, the luxury....nothing can touch it. I looked at a neighbour's Aston Martin DB9 the other day and what struck me was that it was less refined than the XK in the details of design (especially from the front) and in the interior. And, while this is a bit off topic, the other car often compared to the XK is the Maserati, whose exterior and interior look as though designed by a committee incapable of coming to a proper decision. In short the Maserati looks like a failed XK, and the Aston like a first sketch of the XK....hmmm... Isn't that what it was?

 

I have a 2009 Portfolio XKR 4.2SC. It's been my daily driver & I just passed 80K miles. Car still runs as strong as it did when I got it. Outside of routine maintenance I just last week had to change out a few parts. Water pump went bad & the torsion coupler in the supercharger went bad about a day apart. Got that repaired & she's sounding & running great again.

 

From Jaguars engine design dept. All-new XK Powertrain Technology

• New AJ-V8 Gen III engines are more compact, more efficient and much more powerful
• 385bhp, 380lb-ft, 264g/km CO2, 25.2mpg combined fuel economy (naturally aspirated)
• 510bhp, 461lb-ft, 292g/km CO2, 23.0mpg combined fuel economy (supercharged – the Gen III R)
• Conforms to US ULEV II emissions regulations
• High efficiency, sixth-generation twin vortex supercharger on Gen III R engine
• Central spray-guided direct-injection increases efficiency and torque
• Torque-actuated variable camshaft timing on all four camshafts for improved response and efficiency
• Cam profile switching in naturally aspirated engine
• Variable-geometry inlet manifold on naturally aspirated engine further increases low and high-end torque
• Low-friction design optimizes fuel consumption
• 15,000-mile service intervals compared to 10,000-mile intervals on 4.2-liter models

Since the first XK was launched in 1948, generations of powerful yet refined engines have played a crucial role in establishing the unique character and pedigree of Jaguar cars. Now, the new 5.0-liter direct-injection engines continue that tradition, delivering increased power and torque with reduced emissions and impressive fuel economy. Available in two versions, the 510bhp supercharged V8 and the naturally aspirated 385bhp version, the new AJ-V8 Gen III engines exemplify Jaguar’s reputation for innovation and engineering excellence.

Commenting on the new engine range, Ron Lee, Powertrain Group Chief Engineer, said:

“We set ourselves the challenge of developing an all-new V8 engine series that improved on the performance and the refinement of the excellent 4.2-liter, with comparable fuel economy and improved emissions. We have achieved that with the AJ-V8 Gen III – a superbly responsive power unit of unsurpassed efficiency.”

Jaguar’s all-new V8s have been designed in-house, using the expertise of powertrain engineers at Jaguar’s advanced research and development centre at Whitley, Coventry, UK.

Malcolm Sandford, Engine Group Chief Engineer, explains the concept behind the project:

“The emphasis was on delivering efficiency, superior dynamic response and highly accessible low-end torque suited to real-world driving, without compromising power at higher engine speeds.”

The results are clear to see. Performance has been increased by 29 percent and 23 percent (87 and 94bhp) on both naturally aspirated and supercharged engines yet both the naturally aspirated and supercharged engines meet US ULEV II emissions regulations. Despite the significant increases in power, CO2 emissions of the naturally aspirated engine improve on that of the outgoing 4.2-liter V8, while the supercharged engine also produces less CO2 than its predecessor.

Top of the class in more ways than one

Both new AJ-V8 Gen III engines are state-of-the-art in every sense. The technical features have been engineered to deliver unparalleled efficiency, refinement, power and torque for which Jaguar is famous, combined with the lowest possible emissions. Low-speed torque characteristics and throttle response is world-class, while the supercharged version is the most economical 510bhp engine in the market to date.

Summarizing this achievement, Jaguar Programme Director, Mick Mohan, said:

“These engines have been designed by our Powertrain team of over 800 people for the next generation of Jaguar cars. They deliver fantastic straight-line performance and response which is second to none. The combination of power, refinement and driveability is what our customers expect of Jaguar. They are smooth around town, but when you want to drive quickly, the engines are hugely responsive and deliver that classic, Jaguar sound quality.”

Light, robust and very strong

The new V8 engines are built around a stiff, all-new, aluminum block with cast-in iron liners and cross-bolted main bearing caps to reduce noise, vibration and harshness. For the first time at Jaguar the blocks are high pressure die-cast, providing a superior finish and greater dimensional accuracy. The engines use aluminum heads, with four valves per cylinder and strong, spheroidal-graphite cast-iron crankshafts and forged steel connecting rods. The cylinder heads for the first time are specified with a secondary (recycled) aluminum alloy thus reducing the environmental impact of manufacturing the new engine.

The new 5.0-liter direct injection engines are more compact than their predecessors. Overall engine length has been reduced by 0.94-in. by relocation of the oil pump within the engine architecture. This length reduction improves engine bay packaging in support of enhanced safety cell performance while ensuring overall engine weight is virtually unchanged.

New supercharger – more for less

A sixth-generation, twin vortex system (TVS) supercharger is fitted to the XKR’s 510bhp engine. It is a compact Roots-type unit, feeding air through twin intercoolers, which in turn are water-cooled by their own discreet cooling circuit. The high helix rotor design improves the supercharger thermodynamic efficiency by 16 percent over its predecessor. It also improves noise quality to the point where the unit is now virtually inaudible (making supercharger whine a thing of the past). The intercoolers reduce the temperature of the pressurized intake-air and so optimize power and efficiency.

The new air intake has been radically redesigned compared to the previous V8. The intake air path is a direct feed to the supercharger inlet from the centrally mounted front throttle body. Air is delivered through twin air boxes, which reduce flow loss and further increase efficiency.

Mechanically, the new supercharger and its intercoolers are efficiently packaged in the ‘V‘ of the engine to deliver a low overall engine height in support of pedestrian safety requirements.

Industry-first direct injection - power with economy

One of the key features of the new engines is an industry-first, centrally-mounted, multi-hole, spray-guided fuel injection system, delivering fuel at a pressure of up to 150bar directly to the cylinder. This substantially contributes to improved low-speed, dynamic response. The positioning of the injectors ensures fuel is precisely delivered to the center of the combustion chamber, maximizing air-fuel mixing, and improving combustion control. Fuel is delivered via twin, high-pressure fuel pumps that are driven via auxiliary shaft in the all-new engine block.

The charge cooling effects of the direct-injection fuel system have allowed the compression ratio of the naturally aspirated engine to be raised to 11.5:1, further improving the engine economy. The supercharged engine also benefits from an increase from 9.0:1 in the previous 4.2-liter to 9.5:1.

During the engine warm-up phase, the combustion system employs multiple injection mode strategies to deliver 50 percent more heat for fast catalyst warm-up and substantially reduced emissions.

Torque-actuated variable-camshaft timing improves efficiency

A new type of variable camshaft timing system (VCT) introduces another new technology. The four VCT units are activated by the positive and negative torques generated by opening and closing the intake and exhaust valves, instead of by oil pressure. This has allowed the engine oil pump to be reduced in size, saving energy and reducing fuel consumption.
VCT units work independently on all four camshafts with 62 degrees of authority on the inlet cams and 50 degrees of authority on the exhaust cams. Timing is optimized by the engine control unit for torque, power and economy at every point in the engine’s speed range.

The new VCT units are capable of a response rate up to three times faster than before, with actuation rates in excess of 150 degrees per second. This delivers a more immediate engine response to the driver’s demand.

The naturally aspirated engine is also equipped with camshaft profile switching (CPS) on the inlet camshaft. Depending on the engine’s running conditions and the demands of the driver, the CPS will switch between a profile that is ideal for low-speed driving and another which gives increased valve lift for high performance.

Hydraulically-actuated two-piece tappets switch between profiles on the tri-lobe camshaft altering both the lift and duration. The cam lobe profile selected for lower engine speeds has a duration of 214° and lifts the valves 0.22-in. This optimizes gas velocity for improved low-speed torque and reduces valvetrain friction for improved fuel economy. For high-speed driving, CPS switches to a cam lobe with a duration of 250° and valve-lift of 0.41-in., allowing greater air flow into the engine for high power. Switching is activated at 2800rpm at high load, ranging to 4500rpm at light load conditions.

Variable Inlet Manifold optimizes torque through the rev range

A new variable inlet manifold (VIM) can vary the length of its eight inlet tracts to optimize power and torque throughout the rev range on the naturally aspirated engine. Vacuum-operated actuators open valves to select a longer, 27-in., inlet tract at low revs, increasing the rate of both the airflow and the engine torque. As the revs climb beyond 4700rpm, the actuators select a shorter, 14-in. path allowing a greater volume of air into the engine to optimize engine power. The actuator position is optimized by the engine control unit for improved torque throughout the engine speed range.

Reverse cooling turns up the heat

Every component in both V8 engines has been optimized for efficiency, performance, low-end torque and reliability. An innovative reverse-flow cooling system design has been employed to deliver thermodynamic and friction improvements. The reverse-flow cooling system pumps coolant through the cylinder heads before flowing through the block and returning to the radiator. The resulting cooler cylinder heads allow more optimum, knock-free, ignition timings to be used to improve efficiency.

In addition, the 22kW oil-to-water heat exchanger, packaged at the core of the engine, transfers heat from the coolant to the lubricating oil during warm up, bringing the oil up to operating temperature 14 percent faster than the previous cooling system. This improves fuel consumption in the crucial engine warm-up period by approximately 1%.

Reducing friction – something for nothing

Minimizing internal friction is key to improving fuel consumption and CO2 emissions, and as such was a key aim when it came to the design of the engines. As a result, the new Jaguar AJ-V8 Gen III engines achieve another best in class, setting a new industry benchmark for cranktrain efficiency.

All engine bearings were the subject of an extensive optimization program, reducing friction without compromising reliability. Diamond-Like Carbon Coating (DLC) has been used to reduce friction on the fuel pump tappets and a solid film lubricant has been used to coat the piston skirts. New engine oil has a lower viscosity, contributing to an extension in service intervals from 10,000 miles to 15,000 miles or 12 months. Both V8 engines are now fitted with an electronic dipstick feature for added peace of mind.

 

My 2015s XKR's 5L power plant has been flawless. I'm just under 15K miles, but so far it hasn't used a drop of oil, the torque happy engine pulls nicely as has been mentioned elsewhere, and as rev's built so does the excitement!

 

I had the 4.2 NA in an XF for nearly 5 years and about 40,000km, never a day's trouble with the engine. The 5.0 NA I only had for a year, but it was also trouble free. The XKR I have taken to 60,000km (bought it at 40,000) and it has also been flawless. For engine note the 4.2 was my favorite. For performance I'm torn between the ability to cut loose in the 5.0NA and the excess of the XKR. So I think I would have really liked the 4.2 SC which is closer to the 5.0 NA in characteristics, not that I drove 4.2 SC.

The XKR goes next week for a F Type S coupe. Not a better car, just a different one, but one thing I liked was being able to give the 3.0 SC some hammer and not lose traction. To that extent it is closer to the 5.0 NA or what I understand the 4.2 SC to have been.