AMID rising fuel, electricity and food costs, do you manage to stick to your monthly budget? Spare a thought for automakers that have to profitably produce and sell quality products to stay in business while facing the pressures of labour unions, legislation and the escalating costs of raw materials. As a case study, we investigate the innovative engineering decisions that allowed the development and production of the low-volume Jaguar F-Type (which we drive on page 26).
Background
Bean counters and engineers never sit round the same table. Although engineers are able to technically meet most of the customer vehicle requirements (see the How a car is born series in the August to October 2012 issues), accountants tend to tie their hands with budget constraints on a new-vehicle programme. This forces the engineers to come up with ingenious ways of meeting the requirements at reduced cost.
Economies of scale play a big role in the automotive world as most manufacturers make extensive use of suppliers and contractors when developing a vehicle. Unit costs of components are directly linked to volume and this puts added strain on the manufacturers of niche vehicles such as sportscars. Yes, the asking price of a sportscar is generally much higher than a mainstream hatchback’s, but profit margins may actually be lower because of the high component costs and the fact that the capital outlay for the manufacturing plant and total-development bill are amortised over fewer vehicles.
The F-Type
Attending the technical seminars at the global launch of Jaguar’s newest vehicle in Spain and having dinner with some of the engineers allowed insight into the development process of the F-Type. This illuminated some smart engineering decisions that benefited profitability while ensuring that all performance requirements were met.
Simulations
Computer-aided design and dynamic simulations allow engineers to model the entire vehicle in the software realm before a single body panel is stamped. The cost saving is immense because, for example, most packaging problems are solved early with minimal impact on the programme budget. Dimensions, weights and even handling characteristics are known entities before the senior management signs off the complete design. Jaguar conducted more than half a million software simulations to perfect only the front suspension structure in order to meet the stiffness and crash-safety requirements.
Aluminium chassis
Unconstrained by a budget, engineers would immediately choose the lightest and strongest material in conjunction with the best construction method when designing the chassis and body-in-white (BIW) of a sportscar. Currently, a carbon-fibre tub seems to be the optimal solution but the material and production processes are very costly and complicated. Jaguar Land Rover has many years of aluminium-manufacturing experience; the plant in Solihull, UK, at which the latest all-aluminium Range Rover is constructed, is the largest of its kind in the world. Therefore, Jaguar decided to produce the F-Type chassis and BIW from aluminium.
Weight saving, recyclability and energy saving during production are added benefits of aluminium manufacturing. The F-Type structure consists of 141 pressings, 18 die castings and 24 extrusions. Around 2 500 rivets are used to secure the panels (no spot-welding). The biggest engineering challenge on the BIW construction process was the stamping of the large, one-piece bonnet structure while keeping all dimensional tolerances in check.
Powertrain
To develop a new powertrain to meet the power and torque targets, although tempting, is hugely expensive and even the best development and durability programme cannot guarantee real-world reliability. A much safer and less expensive option taken by the Jaguar engineering team was to pick two engines (3,0-litre V6 and 5,0-litre V8) from the Jaguar range and adapt them for the F-Type application. This included active exhaust flaps in the S derivatives to provide the expected sportscar soundtrack.
Jaguar is one of few manufacturers that employ supercharging (which saps power from the engine) to provide boost pressure when most use turbocharging (which uses normally wasted exhaust energy) to reduce CO2 emissions while providing satisfactory performance. According to Jaguar, these engines meet its CO2 targets while the superchargers provide instant response and create the impression of a larger-capacity, naturally aspirated engine that builds power gradually with engine speed. The fastest transmission technology currently in use is the dual-clutch configuration. Even though it would have made sense to use this technology in the F-Type, Jaguar decided to stick to its ZF eight-speed automatic transmission used in other applications owing to the cost benefit. The transmission-calibration engineers managed to decrease shift times of this unit to suit the application. Although the outright shift speed is slightly down on a dual-clutch system, the low-speed behaviour and smoothness aligns better with the ethos of the Jaguar brand.
Electronic differential
Traction is very important, especially in a powerful rear-wheel-drive car like the F-Type V8 S. Therefore, a limited-slip differential is essential. Jaguar did not develop an all-new differential but rather utilises the electronic unit found in the new 5,0-litre supercharged Range Rover. The control calibration was altered for the F-Type application.
Summary
Jaguar curbed costs in the F-Type programme by using existing technology and sharing hardware within the Jaguar Land Rover family. The end result is much more than a sum of the parts; it’s a sportscar that can compete with the opposition both in terms of price and performance. The question now is if sales figures will satisfy the accountants.
Turbos for the Arnage
I was involved in the 2007 Bentley Arnage engine-development programme and witnessed first-hand the difficulty of sourcing new components for a low-volume production vehicle. The programme targets called for 500 hp (373 kW) and it was clear that the previous-generation Garret turbochargers would have to be replaced by more modern units (with lower inertia) with slightly higher capacity to efficiently provide added airflow. As turbopetrols were not as common at the time, it was difficult to source turbos. Secondly, turbo suppliers were unwilling to make capital investments in their facilities that would have enabled them to supply the low-volume demand Bentley needed. In the end, Mitsubishi saved the day by supplying turbos at a reasonable rate.
What killed the Joule?
Optimal Energy, the company that was in the process of developing South Africa’s first production electric vehicle, the Joule, faced a catch-22 situation: to be able to sell the Joule at a market related price for a C-segment family vehicle, it had to produce 50 000 units a year. This would have required massive capital investment (upwards of R9 billion). Producing only a limited number would have required less upfront investment but would have resulted in an extremely high sticker price owing to the expensive component costs without the benefit of economies of scale.
Sharing development costs
To stem development costs, manufacturers form unlikely partnerships or joint ventures on many programmes. Powertrains are widely shared in a multitude of applications (for example, the 1,6-litre turbopetrol unit found in Peugeots, Citroëns and Minis), as well as vehicle platforms (the latest VW/Audi MQB platform). In some instances, complete vehicles are developed together and even built in the same plant before the different badges are fitted. Good examples are the Peugeot 107, Toyota Aygo and Citroën C1. More recently, Toyota and Subaru teamed up to co-develop the 86 and BRZ.
