Extending Jaguar's tradition of introducing engine designs first in its sports car range, the 1997 XK8 debuts with an all-new V8 powertrain exclusive to the model. Designed entirely by Jaguar and manufactured in a dedicated facility in the United Kingdom, this 4.0-liter V8 was engineered to provide refined power.

Designated AJ-V8 inside the company, the engine achieves class leadership in both power output and refinement. At introduction, Jaguar claims best-in-class performance in a variety of measures, including specific power output, weight (441 pounds), power density (engine weight versus power), powertrain rigidity and friction levels. Variable cam phasing helps deliver a minimum of 80 percent of peak torque between 1400 and 6400 rpm, giving responsive performance across a wide range of speeds. A patented high-velocity cooling system helps achieve very fast warm-up, which in turn improves fuel economy.

"This clean-sheet engine design is destined to be ranked alongside the XK-series sixes as a benchmark for responsiveness and engineering brilliance," said Jaguar Cars North America President Michael H. Dale. "It continues a long tradition at Jaguar for designing engines that stir the soul at peak rpm and deliver the broad power range that makes driving an absolute joy."

When the V8 engine design program began, all the binders full of technical requirements and the volumes of market research were distilled to a mission statement of just two words: Refined Power.

"Today, customers take for granted that the engine of every new car, like the car itself, will be both reliable and unfailingly smooth," Dale said. "The AJ-V8 meets those requirements with ease, yet it also provides impressive torque, effortless acceleration and a silky smoothness befitting a Jaguar."

XK8 owners will appreciate the considerations built into the AJ-V8 that reduce or eliminate maintenance. Oil and filter service is at 10,000-mile intervals. Thanks to the use of platinum-tipped spark plugs and chain drive for the camshafts, there is no scheduled engine maintenance needed for the first 100,000 miles aside from oil and filter changes

The AJ-V8 is an all-aluminum, double-overhead camshaft, four-valve-per-cylinder engine with a displacement of 4.0 liters. Maximum output is 290 horsepower at 6,100 rpm and 284 pounds feet of torque at 4,200 rpm. It is the first V8 engine designed by Jaguar, and just the fourth all-new engine in the company's history.

Jaguar research shows that in the current competitive environment, a V8 is the design best able to meet the expectations of buyers in the prestige-automobile segment.

Beyond market demand, the AJ-V8 also strikes an intelligent balance: It delivers very high power from a light and compact package. The AJ-V8 is approximately 12 inches shorter than Jaguar's AJ16 in-line six-cylinder engine.

Engineering centered on delivering extraordinary smoothness, and the AJ-V8 actually betters the fuel efficiency of existing six-cylinder engines of equivalent displacement.

The engineering studies that eventually led to the AJ-V8 began in the mid-1980s. The core design team, established in 1989, produced the first running prototype in November 1991.

Rigorous competitive benchmarking, together with data from market research, led to performance targets for quality, power, smoothness, fuel efficiency, weight and size.

From their earliest discussions, the engineering team focused on making uncompromised quality an intrinsic part of the product. That objective went well beyond designing an engine that would give a long service life. It also meant eliminating every source of repeated, bothersome problems that can emerge throughout an engine's life. To achieve this, they established simultaneous engineering teams -- 17 in all by the end of the project -- to coordinate every phase of design and manufacturing.

These cross-functional teams brought together engineers from many departments with varied backgrounds, pooling their knowledge. By assigning design and development tasks to teams working in parallel and establishing communication links, the engine program shrunk to just 36 months from the time of approval to production.

Another key to delivering a powertrain with leading-edge technology was identifying component suppliers with reputations for best-in-world quality and innovation. By involving them at the earliest possible stages, Jaguar took full advantage of their expertise.

Build quality is advanced through the construction of an exclusive, all-new Jaguar facility at Bridgend, South Wales. Designed using the manufacturing expertise of parent Ford Motor Company, the Jaguar factory-within-a-factory shares the premises of a Ford engine plant to reduce investment. By establishing a dedicated facility, Jaguar fosters its unique identity, which results in a high level of pride in workmanship. The results of the Jaguar team's efforts are known immediately--each AJ-V8 engine is hot tested before it is shipped to the Browns Lane plant in Coventry, England, for final dress and assembly into cars.

The innovative design of the AJ-V8 begins with its most fundamental element: the cylinder block. The die-cast aluminum block employs a structural bedplate to establish a rigid, durable foundation for the engine.

The bedplate is an intricate aluminum casting that forms the portion of the block below the crankshaft centerline, incorporating the five main-bearing caps into a single ladder-type structure. Iron liners are cast at each main bearing position to ensure that bearing clearance remains constant at all temperatures.

Tying the bearing caps (which support the crankshaft) together with the bedplate results in a far stronger engine assembly for long-term durability and less vibration.

The working surface of the cylinder bores is formed by an electroplating process called Nikasil, applied directly to the aluminum of the engine block -- there are no separate iron cylinder liners. The coating, just 0.003 inch thick but extremely long-wearing, is deposited by a precisely controlled procedure in which the plating solutions are pumped through the block in an immersion tank.

The resulting nickel/silicon carbide finish is extraordinarily smooth, offering a number of benefits:

• Lower friction improves fuel economy and durability.
• A faster warm-up lowers emissions, improves fuel economy and ensures that the cabin reaches a comfortable temperature quickly. Engine warm-up is unusually quick -- about four minutes under urban driving conditions.
• Weight is reduced by 15 pounds compared to iron liners.
• Improved oil retention reduces emissions.

Like every Jaguar engine before it, the AJ-V8 incorporates a multitude of leading-edge technologies which contribute to its broad power range, high efficiency and overall durability.

• Crankshaft: The crankshaft is a precision casting of spheroidal graphite (SG) iron, a material that combines light weight and optimum crystal structure for strength and durability.
• Sinterforged connecting rods: The steel connecting rods are an advanced design made by a technique known as sinterforging. In this process, the connecting rod is formed in a single piece with high dimensional accuracy. Unlike conventional rods, the bearing cap at the crankshaft end of the rod is not cut off, but instead fracture-split in a special fixture.

This method intentionally leaves an uneven finish at the cap-to-rod mating surface, allowing the cap to fit back in place only one way -- with the surface irregularities interlocking. The result: The bearing caps securely lock into the proper position and the load exerted on connecting rod bolts is significantly reduced.

• Cylinder head: With double overhead camshafts and four valves per cylinder, the AJ-V8 cylinder head continues a Jaguar tradition of advanced engine design. Engineers chose the four-valve design after testing and rejecting five-valve designs as too heavy and no more efficient.

The efficiency of the engine is aided by a narrow included valve angle, just 28 degrees between the intake and exhaust valves, which also contributes to the compact dimensions of the pent-roof combustion chamber. Additionally, these design features help give the AJ-V8 best-in-class exterior dimensions among V8 engines.

• Camshafts: The camshafts are spheroidal graphite cast iron, rifle-drilled (through the length) to keep weight low.
• Aluminum tappets provide direct, mechanical valve actuation to minimize noise. Thanks to steel shims at the top contact surface and hardened cam lobe surfaces, there is no need to adjust clearances during the life of the engine.
• Variable Cam Phasing: The AJ-V8 employs variable cam phasing (VCP) to reap the midrange benefits of advanced cam timing and the high-speed advantage of retarded valve closing, delivering no less than 80 percent of peak torque between 1400 and 6400 rpm. The timing shift involves only the opening and closing points of the intake valves; it does not change the length of the open period (duration) or the height to which the valve is opened (lift).

The benefit to the driver comes in crisp throttle response, with abundant torque at low speeds and outstanding power as the engine speed climbs toward the top of the tachometer.

The mechanical movement of the intake camshafts is performed by a hydraulic actuator controlled by the engine management system.

At very low engine loads, as well as very low and high engine speeds, the intake camshafts are in the retarded position. In this mode, the valve overlap period (when both the intake and exhaust valves are open) is a minimal five degrees of crankshaft rotation, which provides a smooth, stable idle.

The intake camshafts move to the advanced position when the engine operates at low-to-midrange speeds or at higher loads. In this position, overlap increases, allowing some of the exhaust to flow into the cylinder with the fresh mixture, benefiting emissions control. The exhaust-laden mixture burns cooler, reducing nitrogen oxides, and reburning the exhaust lowers hydrocarbons.

For reliability, the camshafts are driven by zero-maintenance, single-row chains.

• Intake system: The top view of the AJ-V8 is dominated by the curving ductwork of the air intake system, shaped to tune the length of the intake runners for optimum midrange power.

The manifold is formed from a composite material known as Polyamide, which has excellent insulating properties to ensure quick starting when the engine is hot. The interior surfaces are extremely smooth to minimize airflow disturbance.

The fuel rails, which supply gasoline to the individual injectors, are an innovative design: They are integral with the manifold, rather than a separate component, to ensure accurate positioning of the injectors.

• Electronic throttle: The throttle assembly is electronically controlled rather than operated by a conventional cable or linkage. This so-called drive-by-wire function, a technology long proven in aircraft, offers extraordinarily smooth operation, excellent pedal feel and highly accurate idle speed control.

A mechanical backup enables the car to be driven even if the electronics malfunction.

• Exhaust system: Because exhaust emission levels are much higher when an engine is cold, every effort was made to bring the catalytic converters up to operating temperature quickly. The AJ-V8 achieves an unusually fast converter "light off," within 30 seconds of startup.
• Cooling system: The cooling strategy of the AJ-V8 is based on a patented, innovative split-block design, in which coolant flow is divided 50/50 between the cylinder heads and the engine block water jackets.

This allows the cylinder bores to operate at a relatively high temperatures to lower hydrocarbon emissions, meanwhile keeping the cylinder-head temperatures low to enable an unusually high compression ratio (10.75:1) for efficient combustion. The engine warms up in less than four minutes in the standard urban test cycle, aiding cabin comfort, fuel economy and emission control.

• Engine management electronics: The AJ-V8 fuel injection, ignition, emissions control and onboard diagnostic functions are all regulated by the engine control module (ECM), a prime component of the computerized engine management system. The various inputs (throttle position, air temperature, etc.) and the output signals (operating instructions for the ignition and fuel injection) are carried over the car's Controller Area Network (CAN), which enables faster response through more rapid data transfer -- up to one megabyte per second.

The complete engine management system is supplied by Nippondenso, a company with considerable experience in the luxury market. Development work was conducted around the world, from Nagoya, Japan, to Jaguar's Whitley Engineering Centre in Coventry, England.

The XK8 is equipped with a ZF 5HP24 automatic transmission, which offers five forward gear ratios to optimize performance. First through fourth gears are selected for crisp response and effortless acceleration, while fifth is an overdrive ratio to benefit fuel economy. A sophisticated electronic control system not only ensures smooth operation, it also makes possible a versatile shift program that adapts to specific driving conditions.

The need for routine maintenance has even been eliminated: The transmission fluid is installed at the factory, and it never needs to be checked by the owner.

Development of the transmission, including the management electronics, was a joint undertaking of Jaguar and ZF, enabling the gear ratios and operating parameters to be tailored to the characteristics of the AJ-V8 engine.

The transmission's versatility begins with two driver-selectable shift modes, Sport and Normal. Switching into Sport mode times the gear changes for peak response.

The XK8 transmission also carries a self-regulating adaptive capability, enabling it to compensate automatically for the effects of aging and to adjust shift quality based on slippage detected in actual use. Built-in compensation for transmission fluid temperature variations further ensures smooth operation, even in cold weather when the fluid takes longer to reach operating temperature.