Super car, super engine
F1 teams with a string of world championships to their credit demand the absolute best, and no less. That's why McLaren turned to British engineering consultancy Ricardo for help in the design, development, and manufacture of a landmark V8 engine for its brand new MP4-12C road-going supercar. Jesse Crosse hears how Ricardo engineers were able to combine sensational performance with class-leading economy and exacting quality.
[Image: Copyright McLaren Automotive Limited]
Few customers can be as demanding as McLaren; few programs can be as momentous as McLaren's high-profile challenge to Ferrari, Lamborghini, and Porsche with its 330-km/h (205-mph)MP4-12C. Yet in its successful partnership with McLaren Automotive to develop the M838T V8, Ricardo had to chase much more than just sensational performance: This would be a new-era supercar engine -- light, efficient, and environmentally friendly, and manufactured in a specially designed facility setting world-class standards for precision and quality.
Three words "greenest, cleanest, and meanest" succinctly sum up how the new engine sets a series of benchmarks for the industry. Greenest, because it establishes a new yardstick for low CO2 emissions within its class; meanest, because it is the most powerful engine in that class; and leanest because of the high-efficiency, bespoke manufacturing facility built to produce it.
Supercars have a reputation for being anything but environmentally friendly -- their powerful and thirsty engines traditionally giving scant regard to the cost or availability of fuel. With the M838T V8 in the McLaren MP4-12C sports car, Ricardo has changed all that, setting new standards for CO2 emissions, yet at 600 PS also emerging as the most powerful in its class.
Ricardo CEO Dave Shemmans (left) and McLaren group executive chairman Ron Dennis at the opening of the Ricardo High Performance Assembly Facility.
As one of the world's leading automotive engineering consultancies, Ricardo is no stranger to designing complete engines. Yet the McLaren M838T V8 goes a step further: It is the first engine for which Ricardo has also designed the manufacturing system, and the all-new production plant integrated into the company's Shoreham, England, HQ complex is every bit as advanced as the engine itself.
Furthermore, the timescale given from inception to the start of pilot production was exceptionally short -- just 18 months from the middle of 2009 to January 2011. Ricardo's responsibility was to design the new engine from concept to completion, together with all the manufacturing processes, plant, assembly, and testing tools needed to deliver fully built and tested engines to the customer.
"Something that was absolutely key for us, especially since we were tasked with delivering the manufacturing as well as the design and development, was to ensure we had simultaneous engineering between the development team and the manufacturing team," says Tim Yates, project director.
To support the project and achieve its goal, Ricardo needed to assemble teams of skilled engineers as quickly as possible, something that required careful management of numbers throughout the timeline to match the changing demands of this multi-faceted project. Specialists were required for each of nine discrete areas ranging from design and engineering through to supply-chain management. Starting from zero in April 2009, team numbers had reached a peak of 80 just six weeks later; they rose and fell according to need throughout the course of the project before settling back to a lean 35 at the start of production.
Project director Tim Yates explains: "Something that was absolutely key for us, especially since we were tasked with delivering the manufacturing as well as the design and development, was to ensure we had simultaneous engineering between the development team and the manufacturing team."
This involved defining the entire approach from the outset, from the capital investment in buildings and equipment to the number of man-hours needed per engine. From the very beginning a "no faults forward" strategy was adopted, together with 100% data storage and traceability of all components.
Every step was analyzed as the project progressed, changes were made, and the system honed to perfection. By the time the design phase of the project was nearing completion, every question had been answered and all the issues ironed out, both internally and with suppliers. "We made sure we were using world-class suppliers with world-class technology. We are not making hundreds of thousands of engines, and that is a great challenge for the supplier base," says Yates. Some of the best names in the business were chosen using a supplier selection procedure involving standard automotive quality processes and problem-solving tools. The final list includes Bosch, Hummel Formen, Unipart Eberspächer, Capricorn, MHI, and Yazaki.
Design and analysis -- key ingredients
As usual in the design or development of any engine by Ricardo, the company's world-class software tools had a major role to play. WAVE was used to simulate engine performance and 1D gas dynamics, VALDYN to model the valvetrain and drive system dynamics, RINGPAK for piston ring dynamic analysis, VECTIS for CFD work, PISDYN for analyzing piston skirt lubrication and piston secondary dynamics - and, last but not least, ENGDYN for crankshaft and cylinder block analysis.
The earlier DFA (design for assembly) analysis had enabled the team to define key design criteria for the engine early on. For robustness, the DOHC valvetrain design on each bank would incorporate a modern take on classical mechanical shims rather than hydraulic lash adjustment. The difference between these and earlier designs, though, is that the clearances do not need re-adjusting for the entire life of the engine. As a result of the DFA input, the team changed the design of these shims to allow measurement of the followers on the valve tip, with and without shims, to speed up the assembly process.
The front end of the engine, including the timing drive components, was initially rapid-prototyped to establish the assembly sequence prior to purchasing any prototype parts. To avoid any risk of oil leaks, the design team was able to eliminate any T-joints in the lower section of the engine. Special tooling was developed to allow cooling oil jets to be fitted after the piston and rods, thus avoiding a positioning clash during assembly; CAD mock-ups were also used to model the assembly of the compact inlet and exhaust manifold and the turbo assembly.
At the same time as the groundwork was being laid for assembly and manufacture, the design of the engine itself was progressing. It was immediately clear that this was to be a very special engine - the configuration list alone speaks volumes. At 3.8 liters, the M838T is substantially downsized compared to most of its market competitors, yet it is significantly more powerful than any of them. Smaller capacity is a fundamental pre-condition for higher efficiency: both pumping and frictional losses are reduced through the smaller volumes and reduced surface areas. The mass of reciprocating parts is also reduced, as is the total mass of the engine -- to a remarkable 200 kg (441 lb). All of this serves to improve the efficiency and dynamics of the vehicle as a whole.
The M838T in detail
In some ways, the M838T is a classic design, a 90-degree V8 with a fat-plane crank and four valves per cylinder. But despite that superficial orthodoxy and despite its extraordinary robustness, there is nothing ordinary about the specification of the new McLaren V8: in fact, it is cutting edge in almost every respect. The engine has the lowest CO2 emissions in its class -- just 279 g/km -- and meets both EU5 and ULEV2 emissions standards. Power output is a thrilling 600 PS at 7,500 rpm, matched by 600-Nm torque at 3,000 rpm.
Thanks to a clever fundamental design, the compact cylinder block has an exceptionally low mass: not only are the main and lower bedplate crankcases sand cast in aluminum alloy, but so are the top-hung, wet cylinder liners, a feature which saves an additional 4 kg (9 lb) compared to conventional cast iron liners. Careful targeting of the sand cores helps keep the weight down too, and the finished assembly comes in at just 36 kg (79 lb). The fat-plane crankshaft allows a smaller counterweight radius and, combined with the short stroke, this allows a low block height of just 201 mm (7.9 in.) and a crank-to-ground center line height - important for road-holding - of only 121 mm (4.8 in.). Dry-sump lubrication also allows low positioning of the engine in the chassis, and this helps create the lowest possible center of gravity for the MP4-12C.
So-called picture-frame sealing eliminates T-joints in the crankcase assembly and thus the risk of oil leaks, while high levels of feature integration (as opposed to separate components and covers) not only reduce component count and weight, but also the likelihood of faults such as coolant leaks.
Ricardo's analysis tools played a crucial role in designing a high-quality and robust engine, and their use in the development of the cylinder block is a particularly good example. "We did encounter some difficulties, and we are quite open about that," admits Yates. What is important, though, is how those inevitable hurdles were identified and quickly overcome. Early on in the development phase there were some instances of liner cracking, for example, but by looking closely at the clearances, the support, and how the liner was loaded and clamped, these problems were quickly eradicated.
Pumping losses (the energy expended pumping air into and around an engine) are a major source of wasted energy and increased fuel consumption. In the new V8, Ricardo isolated crankcase bays one and four from two and three and also isolated the timing chain case from the crankcase bays. This prevents the transfer or, literally, the pumping, of air between the bays and through internal passages: This significantly improves both power and fuel consumption at high speeds.
The cylinder head is one of the most important assemblies in any engine, and its design makes a particularly important contribution to the performance, emissions, and fuel consumption characteristics. In this case, each of the two cylinder heads has double overhead camshafts, each camshaft being fitted with its own phaser. Like the block, the cylinder heads are optimized for weight, single-piece plastic cam covers giving a net weight saving of 2.3 kg (5 lb) and an aluminum rocker carrier and thin-wall spark plug tube saving a further 2.5 kg (5.5 lb). The narrow included valve angle reduces the width (and weight) of the head and an integrated housing for the variable valve timing gear enables compact oilways and minimizes the overall length of the heads. Again, from the perspective of quality and robustness, single-plane oil sealing rules out oil leaks.
Needless to say, the head design is minutely optimized to maximize performance and minimize fuel consumption and CO2 emissions. Exhaust valve size is maximized to avoid gas flow restriction and to increase the available turbine energy. Intake ports are designed to provide excellent gas flow while retaining good tumble characteristics for efficient fuel-air mixing. The high flow rate reduces pumping losses, and the tumble helps low-speed combustion as well as improving fuel economy at high speed. The quadruple cam phasers improve response, torque, power, and fuel economy throughout the engine speed range.
[Image: Copyright McLaren Automotive Limited]
The valvetrain features end-pivoted finger followers and a single "beehive" design of valve spring, the low mass and high stiffness of which provide accurate valve control at high speed while keeping forces -- and thus frictional losses -- to a minimum. The cam profiles were also designed to improve these characteristics, with the use of VALDYN at the design stage helping eliminate any risk of loss of contact with the camshaft, spring surge, or valve bounce.
The head casting went through a number of development phases after analysis of the first version revealed the potential for excessive temperatures in the exhaust bridge. Thermo-mechanical finite element analysis made it possible to evolve the design of the cooling passages and head gasket shaping to optimize the targeting and velocity of coolant jets, as well as making components easier to manufacture.
Cooling: critical for efficiency
Temperature control is critical to engine efficiency, and for this reason the V8 has a three-plate electrical thermostat which allows higher running temperatures during normal driving and ensures operating temperature is reached very quickly. The three-plate thermostat is effectively three-way or with three valves, so the unit can graduate cooling, something that is especially important during warm-up or during part load. It offsets the huge thermal changes between an engine capable of idling at a few hundred revs producing minimal power and maximum power of 600 PS at 7,500 rpm.
On that note, even the idle speed of the V8 was scrutinized and reduced to 600 rpm from its initial target of 850. "The idle speed was important, and driving that down was something we found we could do," says Yates. "It benefits CO2 emissions and also the noise characteristic of the engine."
Clearly, the sound quality of a supercar engine is crucial, and a considerable amount of work was carried out to get the balance just right both inside and out. Because turbochargers significantly mute the wave form of intake noise, a sound transmission system incorporating a resonator was included to pipe sound to the cabin. The design of the exhaust system also took into account sound quality as well as efficiency. Like the cam covers, the entire inlet manifold is also molded in plastic, reducing weight at the top of the engine to lower the center of gravity.
The test regime was thorough and unforgiving. Five thousand hours of basic testing on seven dynamometers running in shifts served to check and validate every aspect of the new engine, from performance and emissions to mechanical durability testing of individual components. The work included thermal shock testing, with the engine temperature rising to 116 degrees C at full power then being "crashed" back to 20 degrees C using chilled coolant -- a brutal process repeated hundreds of times to verify fatigue performance as well as severely checking the sealing of joints and components.
A further 3,000 hours simulating the famous Nurburgring Nordschleife race circuit using real data logged during track testing there gave the equivalent of 73,000 km (45,360 miles) on-track driving. At the same time, major component and system-level testing were being carried out elsewhere on rigs in a combined test plan between Ricardo, McLaren, and their suppliers. Final vehicle testing comprised more than 1,000,000 km (621,371 miles) on a mixture of road and track at Nardo, Idiada, and the Nordschleife. The final stage prior to production was the building of 95 "made like production" prototypes using production sequences and tools.
At the end of all of this, and just 18 months from the start of the collaboration with Ricardo, a unique new engine was born, possessing spectacular performance and emissions and easily meeting the high-level goals set by McLaren based on the exacting expectations of its very discerning customer base. The MP4-12C that it powers defines a completely new segment within the premium sports car market. To build a brand new car is a challenge; to build a brand new high-performance sports car that is ground-breaking, efficient, high-quality, lightweight, practical, dynamic, safe, comfortable, and visually arresting is a greater challenge still. McLaren - with help from Ricardo and other highly innovative supply-chain partners - looks to have achieved this in considerable style.
And for Ricardo employees and investors, the new High Performance Assembly Facility also provides a proven approach for taking high-performance, Ricardo-developed products into production applying world-class quality principles and practices within a low-volume setting. As such, the facility is both a model factory and a business template that will be of keen interest to many potential customers seeking to add a halo, high-quality performance product to their model line-up.
New engine, new assembly facility, cutting-edge processes
One of the biggest challenges of the program was not just to design and test a new engine ready for production in just 18 months, but to design the assembly process and the 600-sq-m (6,458-sq-ft) plant in which to produce it as well. Ground was broken in April 2010, and the plant was production ready just four months later, in August 2010. "It is a model factory showing how things should be done," says Ricardo Assembly Facility Production Manager Tom Soar.
An obvious question to ask is why the facility is sited in the UK and not in a low-cost location: "We can achieve low cost just as well as anyone else," says Soar, and his views are echoed by no less a figure than Ron Dennis, executive chairman of the McLaren Group: "Several people have asked me why here, in England. I'm fiercely patriotic, and we are desperately trying to communicate the importance of science and engineering for our country," he says. "We came to Ricardo because we had a firm belief in its capability, its science, experience, and commitment to excellence."
The manufacturing building provides a semi-cleanroom environment with a positive air pressure system; it is modular, allowing for easy extension, and a BIPO cell (bed-in and pass-off engine dynamometer cell station) is integral. The production philosophy is one of lean manufacturing, and the line is organized on a single-piece flow (one engine per station), no faults forward basis; the line can take any engine in any order. It has been specified on the basis of producing 2,000 M838T engines per shift per year. Stock control is operated on a "pull" system (where stock control is based on production needs), and there is a 45-minute takt time -- the cycle time before each unit moves to the next station. Two idle stations allow for an increase in production numbers at short notice.
13 assembly stations
The cylinder heads are assembled and set up on a discrete six-point line to one side of the hall, while the main line of 10 stations is positioned in the center of the hall. There are also two sub-assembly stations, making a total of 13 in all. The highly sophisticated cylinder head production line not only builds the cylinder heads with valves, collets, springs, followers, and stem seals but "pops" the valves to ensure they are properly seated. It also performs a leak test on them, installs the camshafts, and confirms all components are present.
All stations have a sophisticated human machine interface (HMI) which contains details of the work, indicates the tool to be used, and keeps track of the status and cycle time. An HMI also controls parts bin selection, warning operators if they are about to select the wrong part. Rechargeable DC battery tools are pre-set and used for fastening, measuring rotations, angle, and torque. All of these readings are stored in a database, giving a full birth history of each engine. Once each operation is complete, an operator acknowledges the fact with a step-completion button. The job is only unlocked ready for the next station if all steps are completed.
Liquid gaskets are applied by machine, and seal integrity is checked with an air pressure liquid leak detector and, if necessary, by using hydrogen gas and a sniffer.
Final stage: Testing and power check
The final stage is for the engine to be bedded in, testing all the engine's functions and also checking power and torque output. The sophisticated BIPO cell used for this stage incorporates hardware from three main UK suppliers and is operated using STARS software. The powerful dynamometer is rated at 460 kW and incorporates automated docking and undocking and coolant and oil fill. It also pre-heats the fluids and is equipped with a number of safety systems including an FM200 fire-suppression system, smoke and flame detectors, and explosion protection. Once the BIPO session is complete, engines are ready for delivery to McLaren Production Center in Woking, England, with a consignment leaving every working day.
This article was originally published in the Ricardo Quarterly review magazine, RQ, issue Q3 2011. Re-published with permission. Designfax is proud to be partnered with Ricardo to bring an insider look into next-gen automotive engineering. For further information contact firstname.lastname@example.org.
Rate this article