There was a time when ‘Jaguar’ and ‘V8’ could not be uttered in the same breath, which is odd when you consider the majesty of the Daimler 2.5 and 4.5 V8s used since the ’60s.
But by the end of the ’80s it was becoming clear that the weight of the gorgeous Jaguar
V12 was just too much, plus its enormous physical size was hampering car design, particularly for crash performance where you need some crumple zone rather than solid engine. The engine was revolutionary in the ’70s, but in the ’80s the labour intensive assembly and expensive parts was costing the company more than it was making. For the last years of the XJS the V12 was not even on the official brochures, it was only its legend that was keeping sales alive.
The AJ6 and AJ16 6 cylinder engines were making almost the same power and saved about 120kg which made a huge difference to the cars handling. But even this engine was showing its age.
New shorter engines were needed in order to allow sufficient room for an effective crumple zone. The engines needed to warm up more quickly, for both customer comfort and the ever tightening emissions regulations. This needs more precise cooling in the heads and block plus the use of considerably less metal. The piston ring system needed to control the oil much more accurately and piston friction had to be lowered. Indeed, friction throughout the engine needed to be reduced to meet the fuel economy and emissions targets.
With these issues in mind, a number of alternatives were looked at in the late ’80s, including a V12 derived V6 with the lost power being returned by using a brace of turbos. Another V6, an Orbital 2 stroke engine which gave the same number of power strokes per rev as the old V12 engine, was looked at but oil control and refinement never quite met the targets. They even looked at a number of engines from other companies, which could be bought in without the huge cost of developing their own engine.
During the dreaded BL days there had been some discussion of using the Buick derived Rover V8, which had substantial advantages in terms of weight (in fact it weighed half as much as the V12), cost and size. Unfortunately, most of the advantage came from the fact that it was relatively thin walled and so suffered in refinement a little. But in reality this could have been developed out, as was the case in the final fling of the Rover V8 inside the P38a Range Rovers.
But that venerable V8 was itself a relic of the ’60s and ultimately suffered from the same issues as the old Jaguar engines, in terms of efficiency and emissions. It also struggled to meet the power demands of modern cars, the 4.6 version only putting out 220bhp.
So the bold decision was made to design a completely new Jaguar engine, one that would meet the forthcoming challenges of regulations and customer expectations. Originally code named the AJ12, the project used a single cylinder research engine to examine a number of different combustion chamber, cylinder head/ port and cam options. This data showed that a 500cc cylinder with 26 degree ports and a four valve configuration gave the best economy and performance for Jaguar applications.
Although AJ12 never resulted in a physical engine, the data was used to study a modular engine design concept, concentrating on a 4 litre 8 cylinder and a 3 litre 6cyl, but also looking at a 2 litre 4 cylinder, a 5 litre 10 cylinder and a 6 litre 12 cylinder engine. This would require some rather sophisticated machinery to be able to make all those variants, sharing common components such as piston and valves but little else. As the analysis data grew, it became clear that the complexity of doing all those variants would be crippling, so it was decided to concentrate on 6, 8 and 12 cylinder V engines. Thus the project now became known as AJ26, 26 being the sum of 6, 8 and 12.
But this would be hugely expensive, the fuel bill alone for testing engines runs into millions of pounds per year. At this time Jaguar was privately owned and as such there was simply not enough spare cash to invest in new products. What was needed was an owner who could suffer the financial hit in the long period between investment and return.
When Ford became interested in buying Jaguar, it was only natural to see if one of their many engines would fit the bill. Indeed it was not uncommon for Jaguar owners in the USA to retro fit a Yank V8 so there was some precedence for this already.
But work had already started on the fledgling Jaguar V8 and the Whitley team, lead by Dave Szczupak, were passionate about seeing it through, they had looked at all the requirements and designed something that would give the legendary levels of Jaguar refinement and power whilst being small, light and efficient. But there would be a long road to go, from a concept to a fully customer ready production engine. Typically it takes around 7 years, that’s a long time to ask an investor to wait for a return.
Ford looked at the arguments for both Ford engines and for the new Jaguar engines, after all the data was analysed and the requirements understood, they decided to invest the millions needed by Jaguar to make their own new engine. But this would be dedicated tooling for just the V8, all other variants were not to be.
The first year had been largely given over to defining the requirements, the specifications for each part of the engine such as how much heat goes into the coolant and the oil, how much force is needed to turn the engine over, valve train stiffness, noise levels as well as the major things like the power and torque levels.
This had lead to the basic design, this was put into the new computers and virtual tests run to establish the best coolant flow paths, the best inlet and exhaust port shape, the cam profiles and the such. A huge amount of data was produced and analysed, without making a single engine. Somewhat different to the early days of the V12 when development was a matter of calculated guess work and then lots of test engines trying it all out.
The calculation gave most of the answers, but some elements still required real world testing. To this end some elements of the new engine were experimented on in isolation, using a current production ‘slave’ engine as a base, giving rise to some odd reports in the press of the new engine being based on this that and the other engine. For example, in order to try different bore and stroke combinations on the single cylinder rig, the engineers looked about for existing parts from all sorts of manufacturers, at one point it was using a Peugeot piston and a Mazda con rod!
The first V8 engines were run on test beds in late ’89 and the first car to receive one was an XJ-S, one of the cars that had just finished being used to evaluate the twin turbo AJ16 in fact. As is always the way with the first ever engine installation, nothing fits, mounts, hoses, air intake and exhaust manifolds all had to be fabricated for the job. Steve, one of the mechanics on the job, recalls ‘they gave me a bag full of exhaust tube and various bends and told me to get on with it’. At the end of ’90, after a couple of weeks of trial and error fitting work the first 4 litre V8 Jag burbled into life and was universally admired by the small select audience of management privileged enough to see it, particularly in America which was a crucial market.
It weighed about the same as the old 6 cyl but had more power and a greater spread of torque, thanks to the new variable cam timing system. But there was a small problem, it didn’t sound like a ‘Jaguar’. Although very appealing, the V8 burble sounded like any normal mid size car in the USA and part of the Jaguar magic was the very high levels of refinement and quietness. Sound is such an emotive thing and much debate was had as to what the new engine should sound like, eventually the decision was made to make it quiet and an enormous amount of work went into designing complex intake and exhaust systems. It is interesting to note how this has changed now such that the current XKR even has a device built into the bulkhead to help you hear the engines magnificent growl.
The first car I drove with the new V8 was an XJ40 in about ’93 at the Ford research centre in Dunton, Essex. The car was based on the XJ12 body, code namedXJ81, which had completely new metal work in front of the bulkhead in order to accept a V engine. This car was bristling with new technology, it had one of the first electronic throttle systems and this particular car had a manual gearbox but with an automatic clutch. As you shifted gear the systems would move the throttle and clutch so as to give you smooth gear shifts. It was marvellous to drive but ultimately it was easier to just use one of the excellent ZF 5 speed auto gearboxes instead.
Its interesting to note how Jaguar has had a history of technological innovation, and how right from the start Jaguar was showing Ford new things. In return Ford showed Jaguar how to massively improve production processes, improving quality and reducing costs. This relationship is continuing to this day, I am pleased to say, with both sides benefiting.
As the engine developed, the early tunes were used to check and refine the basic performance and emissions characteristics. Then cars were used to tune the transient response, that is to say how the engine responds to acceleration, deceleration and gear shifts. This is always a very difficult balance between good drivability and good emissions, a slightly rich fuelling on acceleration give very good drivability but will fail emission completely on hydrocarbons alone.
Part of the solution was to ensure the automatic gearbox control system ‘talked’ to the engine control system. This kept the throttle, fuel and spark precisely in tune with the change in engine speed during the shift, allowing the engine to anticipate the changes rather than have to react to them after the fact.
After the engine had received a good stable tune, it was time to test it in all the harsh climates it would face in the real world. Traditionally this involves driving it in the Arctic and in the deserts of Arizona or Africa. But now tests could also be done in Fords climatic test chambers which drastically cuts down the development time and expense. As well as cold and hot climate tests, the new cars had to be tested in extremes of damp to check the corrosion resistance of the components and all the wiring. Then there is the rough road testing, both on specially prepared test track with a range of harsh surfaces, and on shake rigs where computer controlled hydraulic rams try to shake the car to pieces. In short, a lifetime of use and abuse is concentrated into a matter of months. By the end of ’94 a huge amount of data had been produced and all the necessary changes had been made, the results were looking very good indeed.
After this year of climate and durability tests, the final tweaks could be made and then it was time to start running the cars at government approved test centres to get the various certifications needed to sell a new car. At the same time further tests were re-run in house just to confirm that the final version was working as expected.
In parallel to all this development, the production plant was tooling up. First prototype tooling is made and the whole assembly process is tested, any special tools or assembly methods are identified and the first set of workers are trained. The first few test cars were built this way, as were the cars eventually used for the journalists to drive at the launch in ‘95.
The cost of production tooling is huge, the Bridgend AJV8 plant cost Ford £125 million. So it was vital to be certain that everything was right before the orders were placed, this could only happen when all the test data was in and all the tweaks had been tested. This is still true today and is one of the reasons it takes so long to get a new idea into production.
So, in ’96, seven years after the project started, the first XK8s were sold with the all new, entirely Jaguar, V8 engines. A new era had begun.
The original 4.0 litre V8 went through many detail revisions, and endured the dreded Nickasil debarkle that struck many alluminium bored engines of that era. All the lessons learnt were rolled out together in the later 4.2 litre version of the engine, this unit has a reputation for toughness as well as performance and has been raced with some success too. When Land Rover joined the group it was a natural choice to replace the less than reliable BMW V8 with the trusty and powerfull Jaguar unit. In Discovery it was stretched to 4.4 litres in naturally aspirated form but was left at 4.2 for the supercharged variant, 400bhp seemed perfectly sufficient for a Range Rover back then…..
As with all technology in this rapidly changing modern world, eventually it needed a rethink to regain ground lost to competitors who had brought out engines with the latest innovations. The very name ‘Jaguar’ conjures thoughts of tradition and heritage, but it is easy to forget that a fundamental part of that tradition and heritage is innovation; pushing the boundaries back and surprising the car-buying public. In the 70s and 80s, arguably they made the world’s only mass production V12, and at its launch the XJ6 set new standards in refinement and performance coupled with superb looks and all at a very reasonable price. And whatever you may personally think of the XJ-S, it was a very bold move and still has a very strong following.
The all new AJ-V8 GenIII five litre V8 engine demonstrates the continuation of that innovative tradition, capable of delivering over 500 bhp in a selection of very civilised luxurious cars. And as a demonstration of the engine’s strength, a basically standard engine, a tad over-boosted in a slightly modified XF-R was driven at 225.6 mph on the iconic Bonneville salt flats, faster than the XJ220 super car.
It is interesting to draw a comparison with the magnificent old Jaguar V12, intended to provide approximately 20% greater performance than the 4.2 XK six cylinder engine of the time.
In a similar way, the new AJ-V8 5 litre replaces the 4.2 V8, and pushes power levels up by similar amounts; from 420 to 510 bhp for the R version. However, some things are radically different this time round; the new larger engine manages the rather impressive trick of being significantly more economical than the engine it replaces. An astonishing achievement but absolutely essential in today’s, also radically different, environment.
The V12 was also very advanced for a road car engine at the time, in both its concept and manufacture; it was all alloy and designed for fuel injection from the outset, although they were forced to run carburettors temporarily on the E Type. By comparison the new V8 also uses the latest materials and sports an advanced fuel injection system which heavily influenced the engine design, specifically the cylinder heads with a central fuel injector in each combustion chamber.
The injection concept was proved out before any prototypes were made, on a highly modified current production engine taken out to 4.5 litres. The first real prototype engines were created in 2004 and were immediately and relentlessly tested in engine dynamometers, where each engine can be tested in isolation under precisely controlled conditions. Some engines did specific tests such as trying to deliberately foul the spark plugs, or push the performance limits, and others were run on durability cycles designed to stress components to the max, many a time I walked past a test cell where the exhaust manifolds were glowing bright orange as an engine was run at full tilt.
It is of course the people that really make a company, such as the crack team of expert technicians who build and prepare engines ready for testing, often covered with so much complex test equipment that the engine is totally obscured. Or the chaps in the dedicated powertrain machine shop, a small room packed with tools to weld, cut and machine almost any component, often at short notice, using a mix of the ultra new and the traditional techniques that have served Jaguar engine development for many decades. Research by its very nature involves the unforeseen and as a team, their resourcefulness and creativity has saved many a day. It is the talents of dedicated people like this that form the ‘DNA’ of the company.
After initial assessment of the engines, it soon became clear that the naturally aspirated version would meet its performance targets with ease, something that is quite rare in the rest of the car industry, and the supercharged version could exceed expectations without effort so the original power target was raised from 500 to 510 bhp.
The first car I drove with a prototype engine, in 2007, was one of the first engineering ‘hacks’ and so the engine tune was still splendidly raw. It is from this point that skilled engineers start refining the car’s response, making the car do what the driver wants rather than just reacting to crude mechanical inputs. Before work could begin, this particular car had to be driven from Gaydon, where it had been assembled, to Whitley for testing. As I was making that journey myself I volunteered to take the test car, unfortunately it was pouring with rain and as yet there was no traction control – this lead to a few moments of unintentional entertainment and a degree of sideways progress, but even at that embryonic stage it was still a wonderful car to drive.
Indeed it is an essential part of the vehicle’s development to test drive in every type of likely environment so that the design can be finalised before test cars are sent for official emissions certification all over the world. So cars are out and about with disguise kits on years before launch, trying to avoid the hoards of press photographers camped out in the hedges near the factory. Whenever ‘spy shots’ of a new car are printed, it’s standard practice to work out who was driving and then mock them mercilessly, although sometimes it can land the driver in real trouble if more is revealed than is wise.
As ever, refinement is an essential Jaguar characteristic and this has been achieved by ensuring the moving parts are perfectly balanced in the traditional manner, but also with the new Gasoline Direct Injection (GDI) system, where the fuel is forced directly into the combustion chamber at very high pressure. It controls combustion in such a way as to minimise vibration and noise, effectively by shaping the way the cylinder pressure rises, as well as reducing emissions, better fuel economy and higher performance as if the system raises the fuels octane rating. The whole engine is designed round the system and a lot of hard work ensures all the different factors work in harmony, from the computer synchronised high pressure pumps to the crystal operated injectors that give a sequence of perfectly formed fuel pulses.
The technology has near magical control, when you hit the start button the engine will synchronise, analyse the current air and coolant temperature, check the oil level and temperature, check all the sensors are working, set the fuel pressure on the twin double-acting high pressure pumps, check and adjust throttle angle, set all four cam positions, charge up the ignition coils and the 160 volt injector control circuit and be ready to fire the first cylinder within one revolution of the engine.
And it’s not just the engine that makes for a stunning drive; the gearbox is a lighter yet stronger version of the ZF 6 speed which works in a detailed and complex harmony with the engine, exchanging data and requests in a high speed electronic conference. For instance – when changing gear the gearbox asks the engine to adjust power to balance the kinetic energy left in the drive train and so removing any cause for a jolt or surge, it all happens in a fraction of a second, all for your driving pleasure.
It’s all very impressive stuff and a million miles away from the possibilities available nearly 20 years ago when the design of the last V8 started. The sheer volume of work that goes into the new engine merits a celebration: so for the privileged few of you who get to drive one of these wonderful cars, please take a moment to look under the bonnet, a lot has gone into that modest space.