Author Archives: Marc Jara


Electrification – Software and Testing Solutions

15. October 2019 | Software & Testing Solutions

Electrification – Software and Testing Solutions

Within the next ten years, electric vehicles are expected to account for 90 percent of the market, including full-electric vehicles and various versions of hybrid vehicles. Many new test benches for e-mobility and batteries are being built. So what are the key points we need to understand for this new type of bench? How can we find our way around this new world of tests for electric or hybrid vehicles?

The list of challenges is long. First, and most importantly, are battery tests. Today’s lithium ion batteries provide an energy density 20 to 30 times inferior to gasoline, and to achieve cost parity with a petrol-driven vehicles, we have to cut their costs four-fold. This cannot be done overnight, but the calibration of the BMS (Battery Management System) must be optimized immediately, which requires precise means of optimization on the test bench. For battery test benches, a highly automated and staff-saving process is required. It must be able to react and supervise all the test benches in real time. File formats must be identical, irrespective of their source. In some centers, each device has a different file format, which affects the center’s productivity. In addition, safety is a prime concern with batteries. Great attention must be paid to extreme conditions, in which the internal chemistry in the battery can go out of control. Severe battery tests are necessary, including fire tests, overvoltage tests, crash tests or tests in which the battery goes completely discharged. While the battery is the most sensitive element to be tested, testing electric motors also presents technological issues. Upcoming motors can reach up to 25,000 rpm. In some phases, the temperature suddenly rises, to the detriment of the motor’s longevity. In this case too, the optimization of the global Energy Management System (EMS) will allow critical cases to be managed, increasing the life span of the e-motor.

FEV summarizes the keys to e-mobility test center and system development by highlighting three points: the automated management and global supervision of the processes and the test benches, using the FEVFLEX™ and MORPHEE® software suites. The standardisation of test bench solutions, or Test Cell Products. And, the calibration of the controllers and the optimization of energy management, which demands the extended use of simulation. This vision is the result of more than ten years of experience, with two test centers in Munich and Saint Quentinen-Yvelines (France), equipped with 22 test benches to test batteries, and numerous e-motor and e-axle cells.

Fevflex und Morphee testing process for e-mobility

Fully automated process
A fully automated process is a key factor in any modern test center, but it is particularly important in battery test centers. This is done through software, such as FEVFLEX™ and MORPHEE®. FEVFLEX™ is a modular software suite dedicated to manage and monitor the entire test field. (For more information on using FEVFLEX™ in an e-mobility and battery test center, see article “Expertise and capacity for e-testing projects”, pages 40). All the information sent to FEVFLEX™ is produced by MORPHEE®, FEV’s automation system. The electric revolution is only just starting. Batteries, electric motors and general vehicle architectures are set to evolve even further. In this respect, FEVFLEX™ and MORPHEE®’s upgradeability and applicability makes it a complete must. These open tools can be easily configured by the user, at no additional development cost. MORPHEE can be connected to all types of devices using the same programming interface. It produces and synchronises result files in an identical format, irrespective of the equipment used.

FEV Osiris Powermeter

Test cell products: standard solutions
2019 will be a very special year for ­FEV Software and Testing Solutions , with the launch of the test cell products and standard test bench solutions. Over the years, many benches have been built, both on FEV’s own sites and on customer sites in Europe, Asia and America, ranging from complete engineering projects, to simple automation. FEV has built on this experience to develop standard test bench solutions, or test cell products, that use FEV’s products and products from approved suppliers. Thanks to this standardization, FEV can control costs and propose shorter deployment cycles. This offer covers all the necessary dimensions of the field of electric vehicles, and the safety-related aspects in particular.

FEV proposes battery test benches covering every test case: cell benches with up to 24 cells per climate-controlled chamber, module benches with up to six modules and integrated pack benches, either in walk-in chambers, or in king-sized climate-controlled chambers.

FEV also proposes standard e-motor test benches that can be used to characterise electric motors. The key aspect of this type of test bench is its ability to test at very high speeds and in a highly-dynamic process where vibrations are taken into consideration. FEV produces state-of-the-art e-motor test benches, including dynamometers. It offers e-motor test bench solutions enabling rotational speeds of 25,000. The MORPHEE® solution used to control the bench replaces the bench controller, offering very easy connectivity with the calculators. The e-powertrain is optimized by taking several use cases (motorways, urban environments or rural areas) and several factors (voltage and current signals, frequency versus angular position and speed, transient torque management etc.) into consideration. In this case, FEV’s OSIRIS® Powermeter serves to analyse the efficiency of the e-powertrain system by measuring the power before and after the inverter and before and after the e-motor.

FEV offers unique solutions facilitating not only the optimization, but also the validation of the complete driveline. Durability tests simulating mechanical cycles (vibrations, reducer, differential) and thermal shocks (cooling, rotor thermal management) must also be conducted. In this configuration, a good solution is to test not only the e-motor, but also the complete drive chain. On the so-called e-axle test bench it is possible to test the entire system in the downstream steps of the development process and involves using both MORPHEE® and OSIRIS®, as well as FEV dynamometers and conditioning units for fluid cooling – the so-called eCoolCon™.

FEV e-CoolCon

Energy Management System optimization
The final key factor of success of an e-mobility test center is its capacity to optimize the calibration of the various calculators and the EMS (Energy Management System) of the drivetrain. This was already one of FEV’s strengths in the field of conventional engines, and it is still the case with electric or hybrid motors. FEV has achieved this by developing tools with two characteristic features: a very high level of performance and complete compatibility with one another. In the initial development phases, xMOD™, a virtual experimentation and co-simulation platform, creates a system that was complex to develop by co-simulating the different models that describe it: the electric motor, battery, driver, complete vehicle, etc. Consequently, virtual experiments can be made on the same platform in order to prevalidate the control laws. In the following step, the bench controlled by MORPHEE® – in this case the battery and BMS bench or the e-powertrain bench – is used to integrate the previously validated models by replacing the battery or e-motor model by the physical part, and by keeping all the other parts to produce the most accurate representation possible of the drivetrain in its environment. Since xMOD™ and MORPHEE® share the same DNA, the interfaces, tests and models all follow the same process, from the beginning to the end, in what FEV calls the Collaborative Framework. It should also be noted, that the exceptional simulation performances of these tools, which are 10 to 40 times faster than any other solution on the market, enable highly complex models to run on the test bench in real time.

Morphee Desk and Simulation Screenshot

FEV Group continues strategic path of growth

Turnkey Vehicle Development

29. November 2018 | Corporate

Turnkey Vehicle Development

FEV recently expanded its expertise significantly in several areas at once. With its acquisition of B&W Vehicle Development, the corporate group is widening its expertise and capacities in the turnkey vehicle development segment. With more than three hundred employees at international locations, B&W offers its customers solutions in the fields of body shells, interior, exterior, surfacing, model construction, testing, and electricity/electronics. With the fully owned B&W subsidiary EDL Rethschulte GmbH, expertise in the field of lighting technology is also expanding.

B&W Vehicle Development GmbH is already a force to be reckoned with in the European automotive industry. The company provides its automotive customers worldwide with everything from a single source – from the development of individual modules to entire bodies. With the integration of B&W, the FEV Group can expand its capacities in important fields and also gain employees with engineering expertise in all aspects of vehicle development. At a time of increasingly complex project specifications that aim for holistic vehicle expertise, this step also reinforces FEV’s claim to be a reliable partner in turnkey vehicle development.

Production- and process-optimized product development and construction
The FEV Group also fully acquired Swabian engineering service provider, Suarez & Bewarder GmbH & Co. KG, supplementing its resources and expertise in the fields of interior and exterior automobile development, as well as module and platform strategies for trucks and vans. In the increasingly significant fields of production-ready development, validation, and construction of exterior and interior vehicle components in the context of design and packaging, integrating the two companies allows us to gain new expertise.

Software developer UniPlot creates synergies
Another new member of the corporate group is UniPlot Software GmbH. This company, founded in the 1990s by brothers Samuel and Roman Brüggenkoch, develops software used for the analysis and visual representation of measurement data for a worldwide client base – including well-known companies in the automotive industry. FEV too has been making effective use of UniPlot as an established solution for several years, meaning that absorbing the company is a logical step from which positive synergies are expected.

Stefan Pischinger and Haraldo Brandenburg
From left: Haraldo Brandenburg, Managing Director of B&W Fahrzeug­entwicklung GmbH and Professor Stefan Pischinger, President and CEO of the FEV Group

The new Blackwing 4.2 liter twin turbo V8 engine from General Motors

Blackwing 4.2 liter twin turbo DOHC engine

29. November 2018 | Engineering Service

Blackwing 4.2 liter twin turbo DOHC engine

General Motors has a storied history with V8 architecture engines that are renowned for their performance, durability and refinement. Furthering GMs expertise in V8s, this article describes an all-new 4.2 liter twin turbo, direct injected DOHC engine which is exclusive for use in the Cadillac CT6 V. The engine produces high power at top-end speed but was designed to provide an effortless driving feel by generating best-in-class torque at low and middle engine speeds. The result is an engine capable of meeting the needs of a high power performance sedan while simultaneously providing the crisp throttle response of a luxury automobile. This article provides details of the new engine as well as highlights of individual technologies that support the balanced performance of this engine.

Modern vehicles have experienced a rapid expansion in feature content as the price of computing power drops and consumer expectations increase. This added feature content requires even more packaging space throughout the vehicle. The vehicle under hood area is not immune from these advancements. Added packaging space is required for advanced braking systems, all-wheel-drive transaxles, noise abatement insulation and resonance volumes, and advanced passenger comfort systems taking away space traditionally available for the powertrain. As such, new and innovative designs are needed to create a more compact engine to fit in the space available.

One concept which has become more common in the luxury vehicle market is a turbocharged V8 engine featuring valley mounted turbochargers. This concept provides the benefits of a low volume exhaust system that reduces turbo lag as well as compact packaging to fit in the ever smaller under hood space. With the design freedom of a completely new engine architecture available to the team, it was decided early in the program to adopt the valley mounted turbocharger concept. This enabled the development team to simultaneously meet the transient response, peak torque and peak power targets. In addition, every aspect of the engine, from block height to the connecting rod bearing diameter, was scrutinized for maximum density without sacrificing the engine’s performance or durability and robustness.

Engine performance achievements
Fig. 2: Engine performance achievements

Engine concept
The engine is an entirely new 90° V8 intended for the Cadillac CT6 V, GM’s top-of-range sedan. The main focus of the engine is to develop high torque at low-speeds in order to provide an effortless driving feel. Key performance targets for the engine are shown in Figure 2.
The CT6 V vehicle that the engine is custom designed for was developed to offer an inline 4-cylinder and a 60° V6 as the primary propulsion systems. This made packaging of a DOHC turbocharged V8 a challenge in both width and height. The engine is only available in an all-wheel drive drivetrain further limiting the under hood space for the engine. As a result, the only 90° V8 twin-turbo engine concept that would fit in the vehicle was one where the exhaust and turbochargers were located in the center of the valley with the intake ports on the outside of the cylinder head.

Key specifications of the 4.2 liter twin turbo engine
Fig. 3: Key specifications of the 4.2 liter twin turbo engine

Technical specification
Cylinder block: The cylinder block is a precision sand cast, deep skirt construction from A319 aluminum with a T7 heat treat. The cylinders feature pressed in iron liners while the 4-bolt nodular iron main bearing caps have an additional cross bolting to the skirt to make a stable structure capable of handling the 25.4 bar BMEP.
Given the space available for the engine and AWD differential, every subsystem within the engine was scrutinized for packaging space. For a cylinder block using iron liners, a relatively narrow 96 mm bore spacing and an optimized deck height of 215 mm was achieved. To make the reduced deck height of the cylinder block possible, the outer fasteners for the main bearing cap were angled. This enabled the proper thread engagement for the fastener without encroaching into the piston and hone over travel clearance reliefs as shown in Figure 4.

Transparent view of angled outboard main bearing cap fasteners
Fig 4: Transparent view of angled outboard main bearing cap fasteners

With uneven cylinder filling as an inherent trait of cross-plane crankshaft V8’s, it was critical that the cooling of the combustion chamber be optimized in order to minimize the knock tendencies of the engine and ensure engine durability. With respect to cooling the top of the cylinder bores, a stepped drill was used to flow coolant between the cylinders as shown in Figure 5. This drill directed the coolant from the cooling jacket in the cylinder block to the cylinder head cooling jacket. A metering hole in the head gasket is used to regulate the coolant flow enabling the coolant flow in each cylinder to be metered individually with a unique orifice size based on the temperatures of each cylinder.

CFD results of the flowrate through the inter-bore cooling passage
Fig. 5: CFD results of the flowrate through the inter-bore cooling passage

Cranktrain and powercell: The space available for the cranktrain and powercell was limited by the location of the AWD transfer housing, available packaging space for the starter, and low deck height of the cylinder block. As such, the cranktrain had to be optimized to fit within the given package. To achieve these packaging constraints, the rod bearing diameter was reduced as much as possible to make a small rod path while the main bearing diameter was increased to recapture the required overlap for crankshaft stiffness and strength. The sizes of the bearings plotted on the FEV scatterband in Figure 6 shows how the crankshaft was tailored to fit the packaging constraints of the application.

Main and rod bearing diameter (FEV database)
Fig. 6: Main and rod bearing diameter (FEV database)

The deck height of the engine is also minimized to reduce the overall width of the engine and meet manufacturing clearance requirements when the engine is assembled in the vehicle. To achieve this aggressive target with a relatively long stroke and DOHC architecture, the powercell was scrutinized for minimal length at top dead center. Optimizing the powercell overall length resulted in a short connecting rod that gave an L/R ratio of 3.89. To illustrate how compact this package is, the rod length vs engine stroke for the new V8 engine is plotted on FEV’s scatterband in Figure 7.

Connecting rod length vs. engine stroke (FEV database)
Fig. 7: Connecting rod length vs. engine stroke (FEV database)

The connecting rod is guided by the piston instead of the crankshaft. By reducing the size and relative speed of the bearing area guiding the connecting rod, a reduction in overall friction has been achieved.

Cylinder head: The cylinder heads are Rotocast® from A356 aluminum with a T6 heat treat. This process was selected by the team as it enables superior mechanical properties which are beneficial on a high BMEP engine such as this.

The combustion system was carried over, in part, from the previously released 3.0 L twin turbo V6 LGW engine. The combustion system required several modifications for incorporation into this engine with its valley mounted exhaust. The most prominent was the entrance angle of the intake port which had to be curved upward to facilitate the outboard mounted intake manifold. This upward turned entry drove intake flow to the floor of the port. Significant CFD development was used to ensure the proper amount of tumble was generated with the new design. A comparison between the 4.2L TT and LGW porting is shown in Figure 8.

Comparison between LGW and 4.2L twin turbo porting
Fig. 8: Comparison between LGW and 4.2L twin turbo porting

Extensive work was done to facilitate the cooling of the cylinder head with a single piece cooling jacket. While single piece cooling jackets are relatively conventional, the inboard mounted exhaust ports required a unique coolant flow circuit. In order to achieve a high coolant flow rate through the exhaust valve bridge area, the majority of the coolant is directed from the block into the cylinder head under the exhaust ports, as is the case for most conventional engine arrangements. However, in order for the cooling jacket to degas during coolant fill and in operation, the coolant also exits the cylinder head on the exhaust side of the engine as that is the highest point in the cooling circuit. Thus, the coolant path is designed to enter under the exhaust ports, flow across the combustion chamber, then turn 180° to flow over the exhaust ports where it is collected and returned to the radiator at the front of the engine. Significant CFD development was invested during the development process to ensure that all areas of the head received adequate cooling with a conventional volume coolant flowrate.

Valvetrain and timing drive: The valvetrain was conceptually carried over from the LGW V6 engine with key changes to fit the packaging requirements of the 4.2L TT engine and implement an 8 to 4 cylinder deactivation strategy. The collapsing roller finger followers are actuated via hydraulic pressure that is controlled by cam cover mounted solenoid valves. The development team implemented a cam carrier system to simultaneously reduce friction and provide packaging space for the switching roller finger followers required for cylinder deactivation. This die-cast carrier is complex and houses the camshafts, high pressure fuel pump, and provides worm trail lubrication passages for the cylinder deactivation switching mechanisms.

Intake system and charge air cooling: In order to achieve an extremely crisp throttle response and fast time to torque, the intake volume was minimized by locating the water to air charge air coolers over the cam covers. The intake manifolds are fed directly out of the charge air coolers and cascade over the intake cam side of the cylinder heads into the intake ports. This compact packaging of the intake system, in combination with the low volume exhaust system achieved with a valley mounted turbochargers, was critical to achieving the throttle response targets of the engine without sacrificing the high power targets which requires relatively large turbochargers.
Particular attention was paid to the design of the intake tract such that the charge air coolers were well utilized without the need for restrictive features such as turning vanes. Due to the bank offset of the engine and unique packaging constraints on each side, the charge air coolers were not located in the same position. This required the development of two unique intake tracts with both paths optimized for cooler utilization while maintaining similar volumes. The resulting charge air cooler utilization was above 90 percent for both banks ensuring a balanced charge air temperature for each manifold.

With the charge air coolers being prominently located on the top of the engine, styling cues were included in the housings of each cooler including a “hand crafted with pride” plaque customized and installed by the engine builder on the right charge air cooler. The coolers, accompanied by the aluminum top cover, gives a striking engine appearance when the hood is raised.

Cooling system flow path
Fig. 9: Cooling system flow path

Turbocharging and exhaust system: The engine features two twin-scroll turbochargers that are controlled by electric wastegate actuators. The twin scroll turbochargers feature integral exhaust manifolds for minimum exhaust volume. The turbochargers are mounted to each bank in the valley such that, when combined with the compact intake system previously discussed, an extremely low volume airflow path was realized. Even though the cross-plane V8 does not supply the turbochargers with evenly spaced combustion pulses, the twin scroll turbochargers combined with a low volume exhaust system provides significant transient response and full load benefits without sacrificing classic V8 NVH characteristics.
The valley mounted exhaust manifolds, turbochargers, and catalysts lead to significant thermal challenges under hood. As thermal management was a top concern during the development in order to achieve superior robustness, several heat shielding and valley cooling strategies were tested with multiple strategies implemented. These include direct thermal protection of sensitive components, targeted airflow and heat flow paths, as well as various heat shields. The exhaust manifolds and integrated turbine housings are insulated with contact heat shields. It was found that the contact heat shields with fiber insulation and metallic outer shell provided the best thermal management and required the least packaging space. In addition, because the turbo and manifold heat shields are pre-attached to the parts, assembly sequencing of the hardware in the valley was simplified.

Fuel system: A 350 bar direct injection fuel system was selected to minimize particulate emissions and enable fast combustion at high injection quantities. This system features two intake cam driven fuel pumps with side mounted injectors outside of the valley. Each intake cam features 3 lobes to drive the pumps. A significant amount of multi-body analysis of the camshaft and drive system as well as fuel pressure simulation of the fuel system were conducted to ensure durable operation in combination with optimal engine performance. To meet program targets, the three lobe camshafts were found to better time the fuel pump pulses between the valve events to reduce the peak loading on the timing drive while still providing a consistent fuel delivery.

Lubrication and crankcase ventilation System: At the heart of the lubrication system is a continuously variable vane oil pump. The pump is driven by the nose of the crankshaft and features a PWM controlled solenoid valve that is used to control the eccentricity of the oil pump. The crankcase ventilation system features a valley mounted two-stage oil separator that has dedicated drains at the rear of the engine for the coarse separator and at front of the engine for the fine separator where the separated oil is returned to the oil pan. These drains end below the oil level in the oil pan to prevent crankcase gasses from short circuiting the separator.

The fine separator oil drain is located in a relatively shallow portion at the front of the oil pan. In order to prevent the drain from being uncovered during hard acceleration or cornering, a unique, patent pending design was developed. This design incorporates a reservoir locally around the exit of the drain. The design of this feature was implemented in a cost efficient manner by using one drill for the oil drain and one drill creating the reservoir as can be seen in Figure 10.

Front ventilation separator oil drain reservoir
Fig. 10: Front ventilation separator oil drain reservoir

Engine performance: The engine exhibits class leading performance as can be seen by the power and torque charts shown below. The peak torque of 850 Nm (627 ft-lbs) is available from 2,800 rpm through 4,200 rpm where power peaks at 410 kW (550 hp). The high low-end torque combined with the wide peak torque range offers the Cadillac owner the effortless driving feel that the program targeted from the start of the development.

The torque density of the engine is particularly impressive and matching the best engines on the market even with the breathing dynamics inherent in a cross-plane crankshaft V8 engine. When the scatterband is adjusted to show only V8 engines, the performance is even more impressive.
The results illustrate that this engine is capable of meeting the needs of a high power performance sedan while simultaneously providing the crisp throttle response of a luxury automobile. The engine will fill a critical role for General Motors as it will see exclusive use in the Cadillac CT6 V, GM’s top-of-range sedan.


From engine and powertrain solutions to overall vehicle development

Location Italy

28. November 2018 | Corporate

Location Italy

FEV Italy was founded fourteen years ago in order to position FEV closer to local customers to provide optimal support. Since then, close partnerships have been established with Italian universities, such as the Politecnico di Torino and the Università di Bologna, as well as with other research companies. Two FEV Competence Centers were subsequently opened on this basis, in which, among other things, projects for engine development, engine and vehicle calibration, and benchmarking are being implemented. Earlier this year, FEV opened the Energy Center in Turin.

Thanks to the Italian company STEA, which belongs to the FEV Group, there is an additional focal point on overall vehicle development. At the Italian locations of Turin and Modena, STEA develops extensive mechanical and engineering solutions with a focus on packaging, ergonomics, and layouts. Thus, with growing user expectations regarding functionality and design, FEV is now able to provide its customers with designs for the interior and the exterior from a single source.

FEV Italy employs 160 people and houses three dynamic engine test benches for performance and emission testing for engines with power up to 350 kW, three chassis dynamometers (two and four wheel, 160/250 kW), and a powertrain test bench (for engine, transmission, and hybrid drives).


Immer informiert und auf dem Laufenden bleiben

Engineering Newsletter Subscription

11. January 2018 | Engineering Service

Engineering Newsletter Subscription

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Benchmarking for Competing Technology Strategies

Powertrain Strategies for CO2 Emission Reduction

7. October 2015 | Engineering Service

Powertrain Strategies for CO2 Emission Reduction

The continuous tightening in the regulations and the resulting CO2 emission targets represent a particular challenge for automobile manufacturers in the 2025 timeframe and beyond. While addressing these challenges, carmakers will still need to find cost-efficient technical approaches that don’t compromise customer expectations. In overcoming this trade-off, it is useful to identify the promising concepts and then analyze their relative sensitivity to changing boundary conditions. Typically, more than one “optimum” solution exists. FEV Consulting has developed a comprehensive, structured toolkit to analyze competing technology strategies in terms of CO2 savings potential and cost effects.


Benefits for your business


Powertrain Technology Strategy – Finding the Optimum Solution

The powertrain is characterized by the attributes of its main components, the internal combustion engine (ICE) and transmission. With hybridization concepts, this scope is extended by the powertrain topology and additional electrical components. Powertrain efficiency is the primary factor influencing CO2 emissions, along with the driver behavior and vehicle characteristics. This suggests the existence of multiple paths for compliance with tightened CO2 emission targets. “Identifying the most advantageous path highly depends on the carmaker‘s existing technology portfolio and competencies,” explains Dr. Michael Wittler, Manager at FEV Consulting. FEV Consulting uses an approach that leads to robust powertrain and electrification strategies, considering the individual and regional boundary conditions. The modeling of manufacturer-specific vehicle fleet CO2 emissions makes possible the identification of target values for vehicle segments and drive types. The resulting technology packages are described in detail and assessed with respect to their benefit in terms of the CO2 reduction vs. additional cost trade-off.


An integrated approach is applied for the evaluation of ICE technologies, transmissions and vehicles. Expert knowledge is leveraged within an automated and intuitive procedural approach. New technologies are continually implemented and evaluated. The results of this process support identification of the most beneficial automaker-specific technology configurations. In addition, this method allows analysis and comparison of technology trends and helps to find answers to challenging questions. For example, will downsizing be the right approach if the EU implements the WLTP as the standard drive cycle, replacing the NEDC?

CO2 Emission Fleet Strategy – Understanding the Industry Dynamics

FEV Consulting has developed a comprehensive method for estimating and modelling OEM-specific future strategies to support achieving their individual targets by 2025. The vehicle segment portfolios for each automaker are described on the basis of the type of powertrain, considering the specific type of fuel (e.g., gasoline, diesel), the type of hybridization (e.g., mild hybrid, plug-in hybrid), or the vehicle’s market share in that segment in the case of pure electric vehicles. Based on the latest registration data, the future vehicle segment portfolio and powertrain type distribution are forecast for each auto-maker. Improvements in efficiency are applied to the powertrain types in each specific segment, including the transmission. The improvements gained by vehicle measures are also considered. The results take all regionally-specific legislation into account, e.g., for counting super credits or eco innovations. “Finally, various scenarios can be simulated and the resulting strategy analysis identifies how efficiency technologies can best be leveraged with regard to the targeted achievements,” concludes Dr. Wittler.



Reducing the number of cylinders of commercial engines

1. October 2015 | Engineering Service

Reducing the number of cylinders of commercial engines

Downsizing is an effective measure to reduce fuel consumption in passenger car engines. However, this trend cannot be readily transferred from passenger cars to commercial vehicles. Here the focus is on “rightsizing” with the aim to better adapt the displacement of the engines to the power target. Savings – particularly in view of the cost of production – can also be achieved by reducing the number of cylinders at constant displacement, as FEV studies have shown.

Commercial vehicle engines must comply with harsh exhaust emission limits even under full load. In addition, a comparatively low nominal speed and high expectations for the durability of the maximum specific power represent limitations. While automotive engines already reach values of more than 70 kW per liter, heavy commercial vehicle engines have not yet gone beyond a maximum of about 35 kW per liter.

Decreased number of cylinders, identical power, equivalent displacement

“A trend is developing with regard to rightsizing in commercial vehicle applications,” explains Dr. Peter Heuser, Group Vice President, Commercial Vehicles, Industrial and Heavy-Duty Engines. “In recent years, all of the major commercial vehicle manufacturers engines have introduced 10L class engines into the market and, thus, the gap between the conventional 7L medium-duty and the 12L heavy-duty engine has been closed.”


Investigations by FEV indicate that the production cost of an engine with a predetermined performance can be effectively reduced by reducing the number of cylinders and then increasing the displacement of the remaining cylinders, accordingly.

This can be achieved by replacing a six cylinder engine with a four cylinder engine that has a 1.5 times larger single-cylinder displacement. In addition to the reduced cost, the required installation space and the weight can be reduced while, at the same time, achieving higher efficiency. The deterioration of NVH performance due to the greater ignition interval and the free second order inertia forces can be almost fully offset with a dual-mass flywheel and mass balancing shafts. These additional components were included in the review in terms of cost, size, weight and fuel consumption.

Cost savings through modularity

Four cylinder engines with a cylinder displacement of about two liters, which is standard for heavy-duty-engines open up more than just the potential cost savings of reducing the number of cylinders. The fact that a larger power range can be covered with a common cylinder diameter allows modularity and parts commonality that leads to improvements across the entire engine family.

Rightsizing - Comparison of a 4-cylinder engine with a 6-cylinder

Comparison of a 4-cylinder engine with a 6-cylinder with equal displacement

Rightsizing - MD and HD Engine Family

MD and HD Engine Family