This is the story of the leap from the K1200 to the K1300 engine and driveline, as seen through the eyes of Ricardo Engineering, who did the development work on behalf of BMW and also of BMW who took the unusual decision to outsource the work.
This article was plagiarised from the Ricardo Engineering internal Quarterly Review newsletter published in Q2 2009, absolutely without permission. The full, glossy document can be downloaded (at a cost) from...
https://www.scribd.com/document/136844803/BMW-K1300-Engine-Case-Study...or you can drop me an e-mail if you would like a copy.
The text is presented here as it was produced, errors and omissions excepted, typos corrected and shiny photos left out.
It is interesting to note the extremely correct and politically expedient language used in such a document, 'light load combustion instability' rather than 'engine hesitating, stumbling and stalling at low revs causing bikes to fall over and press test riders to slag the bike to the high heavens and back'. At least, that was my description of the problem after the first 100 miles on my 2004 K1200S. Ho hum!
Enjoy!
BMW’s “Brilliant†engineIt is not just for premium cars that BMW is world famous: it is also renowned for producing some of the world’s finest motorcycles. In 2006 BMW approached Ricardo to participate in an engineering programme that would help to develop a new four-cylinder engine for its K 1300 motorcycle to be launched in late 2008. Jesse Crosse and Anthony Smith describe a fascinating engineering collaboration
Although extremely well known for its powertrain technology for four-wheeled vehicles, Ricardo made the headlines in the world’s motorcycle press earlier this year for the assistance it provided to BMW in the development of a major premium motorcycle, the K 1300. Commissioned in 2006, the project lasted 30 months and culminated in the launch of the revised K 1300 range consisting of the K 1300S, K 1300R and K 1300GT motorcycles to a rapturous response from journalists around the globe.
Ricardo has been undertaking motorcycle projects throughout the company’s entire history but has been particularly active over the past 20 years, serving manufacturers world- wide from scooters and tuk-tuks in the developing nations to the premium products of the leading brands of Europe, North America and Japan. To consolidate and develop this aspect of the company’s service, a global centre of excellence in motorcycles and small engines has been established by Uwe Moser, product group director for gasoline engines at the Ricardo Schwäbisch Gmünd Technical Centre in southern Germany.
“Before the K 1300 project we had already been maintaining close ties with BMW Motorrad in Munich through our work on a number of exhaust system development projects.
Then when in early 2006 a request for quotation arrived for support for a major upgrade to the K 1200 four-cylinder engine, it was clearly appropriate that we should base the Ricardo aspects of the programme here given our very close location to BMW.â€
Despite having one of the strongest and most respected engineering organisations in the motorcycle industry, BMW had a clear rationale for requesting external engineering support. With its highly ambitious – indeed unprecedented – new product strategy, it would require an additional engineering resource capable of operating seamlessly as a part of the BMW product development process and staffed by skilled engineers knowledgeable in the unique requirements of motorcycle development.
The engineering challenge for the upgrade programme was no less significant, requiring an increase in capacity from 1200 to 1300cc, something that would actually necessitate a substantial re-working of the engine.
Ricardo was subsequently awarded the contract, along with full responsibility for the programme, and work started immediately in June 2006. “BMW particularly liked the fact that we could deliver a complete package in-house, including transmission and exhaust, from a technical centre which could provide motorcycle- specific engineering expertise close to its own Munich based operations,†continues Moser.
“The idea of outsourcing such a major project was quite a departure for BMW, but our location and the existence of the centre of excellence in motorcycle engineering made the prospect of collaboration with Ricardo an attractive option.â€
In order to bring the best skills to bear that Ricardo has to offer, Paul Etheridge, Ricardo chief engineer for motorcycles and small engines, was asked to relocate from the UK to Schwäbisch Gmünd in order to lead the programme. An avid motorcycle enthusiast in his personal life as well as a respected industry expert, he was able to draw on motorcycle expertise across four international Ricardo sites: Shoreham and Leamington in the UK, as well as Germany and the Czech Republic.
The K 1200 had been in production since 2004 and it was important to keep as many of the common components as possible. Major castings would remain unchanged, but there would be a 1mm increase in the cylinder bore (the maximum possible with the existingcrankcase) and a 5.3 mm increase in stroke, increasing the capacityfrom 1157 to 1293 cc. Altogether that would require at the very minimum a new crankshaft,
connecting rods and pistons as well as improvements to the combustion and exhaust system.
Significant undertakingDespite being an upgrade rather than a complete new engine, Etheridge realised this would be a significant undertaking.
The increased performance would require a review of the design of the crankshaft bearings, crankshaft balance, the thermal and structural characteristics of the crankcases and cylinder head, and the combustion system. Improved refinement and shift quality was requested too and there would be a complete redesign of the exhaust system, plus a thorough recalibration of the engine management system.
Ricardo’s vast array of software tools made it possible to do a thorough job on all of these elements quickly, says Etheridge. “We did a full sweep of CAE work using WAVE, FLOWMASTER, VALDYN, and our FEARCE (finite element) codes.†VALDYN was used for driveline dynamic modelling and particularly for identification of resonances in the clutch as well as NVH in the shaft drive. As it later transpired, the results would correlate exactly with the finished prototypes.
Three BMW models were lined up to receive the new engine: the ‘naked’ K 1300R, the sports K 1300S and the K 1300GT touring bike. To ensure that the needs of all three bikes would be met with the revised engines, Ricardo would need to adopt and follow all of the BMW processes from concept to production, something which involves multiple prototype phases.
An early prototype comprising the very first running engine ‘off the board’ was built using some solid machined components, sand castings and other rapid prototype parts. Subsequent prototypes moved closer to production with forged crankshafts and connecting rods and, later still, components were made using production tooling but without adhering completely to production processes.
The final step is to manufacture engines using full tooling and production processes. Naturally, exhaustive validation and testing were needed at every step. Engines underwent many hours of testing on dynamometers before being installed in motorcycles for durability testing on chassis dynamometers. “Only then would we put a man on the bike for road testing,†says Etheridge.
All programme milestones metThe work rate during these phases was prolific, to say the least, with increasing numbers of engines built at each prototype stage. Despite the project being intended as one to upgrade an engine rather than the design of an entirely new one, there was nevertheless a phenomenal amount of detail involved in its execution. There were power and torque targets to meet, production variability had to be considered, breather and oil systems were re-validated, engines were fully calibrated and Ricardo provided calibration support to BMW right through to sign-off.
During the project Ricardo was responsible for working with BMW engineers to meet all of the exacting technical and programme milestones for the new engine. This included working with BMW drawing standards and being given complete access to CAD systems for the generation and modification of drawings and specifications – so much so, recalls Etheridge, “that Ricardo became an extension of the BMW engineering team."
The upgrade expands in scopeDuring early development work Ricardo and BMW identified that the light load combustion stability needed to be improved in the new engine compared with its predecessor, to improve the low speed driveability of the bike.
“A few years ago,†explains Etheridge, “customers accepted a lower combustion stability at light loads as the norm with a high- performance bike, but now they are much more discerning.â€
The initial brief from BMW was to carry over the existing cylinder head and valve train from the K 1200. The engineering team felt that this characteristic might be addressable on the new engine via calibration refinement, but it soon became clear to both BMW and Ricardo that mechanical design changes would also be required.
Combustion stability can be affected by a number of things, the main areas being calibration, in-cylinder air motion, fuel/air mixing, combustion system design and the level of residual exhaust gas in the cylinder through intake and exhaust valve overlap. Not surprisingly, fixing this problem turned out to be something of a combustion system development project in its own right, rather than a detail requiring minor adjustment.
Using WAVE and VECTIS to model the induction process, in combination with measurements made on test rigs and use of the Ricardo design of the experiments toolset, the team identified a number of areas that could be improved. The main culprit was identified as the substantial combustion residuals at light load from the selected valve timings, which erred on the side of performance and top-end power. Ricardo’s extensive experience in combustion modelling indicates that a certain level of residuals can be tolerated; any more and combustion becomes unstable.
Next came simulation and testing of many different combinations of valve lift, period and overlap to arrive at the best possible camshaft profiles for power and torque, but without exceeding the exhaust gas residuals target. This, combined with a new inlet port design, completely transformed the low-speed behaviour of the engine. In addition, the combustion system improvements reduced fuel consumption and exhaust emissions.
The new design of intake port improved the in-cylinder air motion and helped to control residual combustion gases. Next, changing the camshaft phasing and profiles, together with recalibration,
smoothed the engine’s low-speed response completely. Much of the work revolved around striking the right balance between outright performance and dynamic stability at low engine speeds – but after four months the work was completed and the changes incorporated into production designs. The study of this phenomenon having been completed, a prototype bike was produced with the proposed modifications in order to validate and build confidence in the recommendations arising from the study. BMW project engineers and senior management rode the bike and signed off the development before the productionisation work commenced.
The combustion system work undertaken by Ricardo and the result obtained on the bike was considered a great success by BMW, and clearly showed how the cause of an undesirable but very subjective vehicle characteristic could be identified and solved during the early stages of engine development thanks to the use of the right tools, techniques and expertise.
Improving engine and driveline dynamicsDue to the increased capacity, power and torque, all aspects of the K 1300’s bottom end and driveline needed reviewing. The first task was to make a rotational dynamics model of the original K 1200 cranktrain using VALDYN, and to calculate bearing loads and crankshaft strength using ENGDYN in order to provide a base load for comparison. A new connecting rod was designed to suit the bigger engine’s new pistons, based on an analysis of shank strength. In addition, the analysis of the crankshaft revealed that the existing crankshaft bearings would be more than strong enough despite the increased bearing loads.
The crankshaft counter-weighting needed careful adjustment because packaging was tight inside the crankcase and also because the bigger engine’s crankshaft would inevitably have a greater variation in cyclic speed. So as much inertia as possible was packaged within the crankshaft itself to better control the effect, and balance the loads on the main bearings.
Given the larger bore sizes and increased loads, a rigorous stress analysis was made of both the crankshaft and crankcases using finite element modelling. The results showed that all the safety factors remained well within limits and no major modifications would be necessary.
VALDYN was also used to make a rotational dynamics model of both the original K 1200 and the proposed K 1300 drivelines, from the pistons right through to the rear wheel. The K 1200 model was then adjusted to match physical measurements made on the bike of torsional motion at various points in the driveline. The results provided new information on how the driveline behaved so that the model could then be modified to represent the K 1300. This proved to be an extremely useful tool and an effective guide in selecting clutch stiffness and damping, scissor gear stiffness, damping and preload. This work led to the development of a new 2-stage driveshaft in order to further optimise gear shift dynamics and hence shift quality.
Using this kind of ‘linearised frequency domain’ model is very unusual in the analysis of a motorcycle driveline but proved extremely effective, reducing the number of design changes needed and the amount of physical testing that would be required later in the K 1300’s development cycle. As with the combustion development work, a prototype was produced to demonstrate the benefits of the proposed modifications, which again was signed off for productionisation by BMW project engineers and senior management.
Full responsibilityRicardo had full responsibility for exhaust system design, sound quality and NVH, and worked closely with BMW’s exhaust supplier. The base OEM exhaust design included a sophisticated reactive silencer; but Ricardo also worked closely with an after sales supplier of high performance aftermarket motorcycle exhausts, to develop a sports version available as an option on the K 1300R and S models.
Design of the OEM system involved thermal, mechanical and finite element analysis, plus some physical measurements of aspects such as exhaust vibration levels, to meet BMW’s stringent standards. The final product included a flap valve, enabling it to meet global noise regulations in drive-by tests, while still producing the kind of compelling exhaust note that customers demand. Having the right kind of sound is a key selling point, and the result has been a great success.
Praise in the motorcycle pressThe entire programme lasted only 30 months, from May 2006 to January 2009, with production having started in October 2008 at BMW’s Berlin plant. The new BMW machines have already been tested by the international motorcycle press: the world’s leading motorcycle weekly, Motorcycle News, concluded simply that “the engine is brilliantâ€, while Superbike magazine hailed the K 1300 range as “a genuine leap forward†with performance “simply staggeringâ€.
In addition to such public acclaim, this project has shown how Ricardo was able to offer a comprehensive capability to work in partnership with and as an integral part of BMW’s own engineering team. Key stages of the programme were delivered in record time using some of the latest CAE and design technologies, and a truly remarkable product has resulted from a unique collaboration between Ricardo and BMW.
The Ricardo perspectiveThe Ricardo Centre of excellence in motorcycle and small engine engineeringThe Ricardo technical centre at Schwäbisch Gmünd in southern Germany is home to the company’s centre of excellence in motorcycles and small engines. This is one of many such centres of excellence providing a group-wide specialist resource and expertise to Ricardo’s product groups and major programme teams.
“The rationale for the creation of this centre of excellence is simple,†explains Uwe Moser. “Motorcycles and small engines frequently have application-specific requirements that are fundamentally different from those of the automotive sector. Volumes in particular can vary widely from niche applications such as micro-UAV engines, through to hand-held tool applications where the quantities produced can often exceed those of mainstream automotive products.
At the same time they tend to share many of the more stringent design targets such as optimised fuel consumption, NVH, emissions and, of course, lifetime cost.â€
In leading development programmes in its own right, the centre of excellence can draw upon resources from the entire Ricardo group while delivering engineering support based on a deep knowledge of product requirements and the capabilities available from the global component supplier base.
The centre is also able to provide this same expert assistance to programmes led elsewhere in the global Ricardo organisations such that the company can thus provide best- price technology and quality for its motorcycle and small engine clients, regardless of their location.
Like motorcycle engineering teams the world over, the commitment brought to the engineering process is in many respects akin to that of a motorsports team. For example, to ensure that early K 1300 programme targets were met, the team at Schwäbisch Gmünd worked solidly through the Christmas holiday of 2006, taking just a single day off, in order to deliver the first 15 prototype engines on time to BMW. In testing, not a single one failed to deliver its power target.
“For motorcycle projects in particular, a thorough understanding of the product is crucial to the quality of the engineering solutions delivered to customers,†concludes Moser. “Over 80 per cent of our motorcycle and small engine centre of excellence staff members are active motorcyclists, and their passion for the product makes a real difference in a market in which performance, quality and competition are everything.â€
End.
See following post for the BMW Perspective (due to the draconian 20,000 character limit on posts in here).
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