The water pump is the crucial component of the engine cooling system. It is usually designed considering as rated conditions the ones evaluated when the engine delivers its maximum power. This results in an overdesign of the pump, considering that almost never the engine delivers the maximum power, in usual operation. At these conditions, in fact, flow rate and pressure delivered reach the maximum values, which are not needed to cool the engine in most probable operating conditions. In fact, considering the real operating conditions during a typical driving mission or a homologation cycle, the mechanical power is far away from the maximum datum, as well as the cooling flow rate and pressure delivered by the pump. To a so unbalanced design for the pump corresponds a low efficiency of it, being the technology oriented to use a centrifugal type, whose efficiency is quite dependent on speed of revolution and flow rate delivered. Hence, modifying the design point of the pump causes a

Di Battista, Davide, Deriszadeh, Ali, Di Prospero, Federico, Di Giovine, Giammarco, Di Bartolomeo, Marco, Fatigati, Fabio, Cipollone, Roberto

Methodology of Minimum Energy Starting for SI Engine

2025-32-0090

11/03/2025

In general-purpose small SI engines, it is necessary to reduce fuel consumption under operating conditions involving repeated starts and stops. In other words, the energy distribution during the transition from 0 rpm to idling speed is a crucial factor. At startup, the SI engine must be driven by a motor, and the electrical energy required should be minimized. However, the engine must accelerate during this process, and the required electrical energy is influenced by factors such as compression, friction, and moments of inertia. The purpose of this research is to experimentally clarify the conditions for minimum energy starting in SI engines. Specifically, the effect of the moment of inertia was eliminated by using a motor to maintain a constant engine speed, thereby enabling the isolation and measurement of electrical energy consumed by friction. The electrical energy required to overcome the moment of inertia can be determined by comparing it with the energy consumed when

Matsuura, Yusuke, Tanaka, Junya

Traction Voltage Level in Two-Wheeler: Considerations on E-Motor Performance

2025-32-0093

11/03/2025

The electric power of most electric two-wheelers on the market ranges between 2 and 12 kW. For this power range, the traction voltage level is mostly between 48V and 96V. There appears to be no strong correlation between electric power and traction voltage, suggesting that the current voltage choice is rather arbitrary. This paper briefly describes the e-motor model used in this study and introduces variations of four design parameters: DC voltage, maximum phase current, e-motor active length, and the number of turns in the e-motor winding. The consequences of these variations on peak performance, continuous performance, and efficiency maps are presented. Specific cases of parameter combinations are also studied. Two e-motors designed for 48V and 96V systems will be compared, showing that size, cost, and performance (power and losses) are equivalent. Additionally, the paper discusses how increasing the maximum phase current rating of the inverter can improve e-motor power in a 48V

Albert, Laurent

Knock Sensors for Two Wheelers Applications

2025-32-0079

11/03/2025

This paper describes the design and characteristics of the knock sensor. The sensor is already used as a commodity product for automotive applications and used by all automotive OEMs for spark ignited combustion engines. With the arrival of the electronic fuel injection on the two wheelers, further optimization of the combustion can be obtained. Although there are many publications on the engine knock strategy, little is known publicly about the sensor itself. The knock sensor is an accelerometer based on a piezoelectric component; it provides an analog signal of the engine vibration. The Electronic Control Unit will filter the signal according to a specific strategy and defines the presence and intensity of the engine knock. The ECU will act accordingly on the ignition timing. The inner structure as well as the mechanical and electrical interface are described in this article.

van Est, Jeroen, Prieu, Corentin

Vehicle to Vehicle Recharge and Power Sharing for Modular Public Transportation Systems: Design and Testing of the UNIFI fleet at ENEA CASACCIA Research Center

2025-32-0095

11/03/2025

The synergistic adoption of automated driving technologies and the electrification of the vehicle power train offers the possibility of proposing new and innovative solutions for public transportation systems. In particular, an interesting solution is represented by modular systems in which multiple autonomous vehicles/transportation modules can be aggregated to form reconfigurable compositions according to desired transportation demand. In this work, a configurable connection between vehicles is adopted, as convoying ensures the possibility of power sharing between vehicles, allowing coordinated power management throughout the composition. Connected vehicles can also share power between batteries for battery recharge that is performed using a custom solution from a tram-like catenary. In this work, the authors design a demonstrator to investigate the feasibility of the proposed solution. Once designed, the proposed system has been assembled and tested at the ENEA Casaccia Research

Alessandrini, Adriano, Berzi, Lorenzo, Fabbri, Marco, Franci, Michael, Gulino, Michelangelo Santo, Pugi, Luca, Ortenzi, Fernando, Vitiello, Francesco

Computational Investigation on a Boosted Uniflow Scavenged Direct-Injection Combustion Engine (BUSDICE) with Alcohol Fuels

2025-32-0027

11/03/2025

Alcohol fuels, produced from renewable energy sources, are considered a crucial solution for achieving life-cycle carbon neutrality in internal combustion engines. The Boosted Uniflow Scavenged Direct-Injection Combustion Engine (BUSDICE) exhibits significant potential for high thermal efficiency with an aggressive downsizing design. In this study, a computational investigation was carried out to assess the spray mixing and combustion characteristics of BUSDICE fuelled with methanol and ethanol, compared with gasoline, under a high-load condition. The injection duration of methanol and ethanol is significantly longer than that of iso-octane, leading to incomplete evaporation. The mixture exhibits an “outer-rich, central-lean” stratification pattern due to the short mixing time and swirl flow transportation for all three fuels. However, the prolonged injection of methanol induces stronger turbulence, which can enhance the local mixing. The spatial mixture stratification, particularly

Feng, Yizhuo, Lu, Enshen, Dong, Shuo, Keshtkar, Hossein, Wang, Xinyan, Zhao, Hua

Experimental Analysis of Wheel Bearing Friction Losses Under Realistic Driving Cycles on a Component and Roller Test Bench

2025-32-0100

11/03/2025

The ongoing electrification of vehicle powertrains brings attention to components with a minor contribution to overall friction losses in research and development. To optimize the overall energy efficiency, it is essential to analyze and reduce the losses in these components. Wheel bearings are of particular interest in this context, as their friction losses affect both the driving and recuperation phases. These losses are dependent on temperature, mechanical loads and the bearing mounting situation into the vehicle. The analysis of friction losses and their dependency on the factors mentioned above is usually conducted by measurements on component test benches to allow an isolated analysis. In contrast, the friction losses of the complete drive system are measured on powertrain or roller test benches. In this context, the factors affecting the losses in wheel bearings deviate from the measurements obtained on component test benches. The purpose of this paper is to analyses the effect

Hartmann, Lukas, Erxleben, Lars, Rebesberger, Ron, Henze, Roman, Sturm, Axel

Forward-Looking SiL-Based Fuel Consumption Simulation for Dual-Clutch Transmission Software Evaluation

2025-32-0070

11/03/2025

Evaluating the impact of software changes on fuel consumption and emissions is a critical aspect of transmission development. To evaluate the trade-offs between performance improvements and potential negative effects on efficiency, a forward-looking Software-in-the-Loop (SiL) simulation has been developed. Unlike backward calculations that derive fuel consumption based solely on cycle speed and engine speed, this approach executes complete driving cycles as the Worldwide Harmonized Light-Duty Vehicle Test Cycle (WLTC) within a detailed SiL environment. By considering all relevant influencing factors in a dynamic simulation, the method provides a more accurate assessment of fuel consumption and emission differences between two versions of the transmission software. The significant contribution of this work lies in the high-fidelity integration of a real virtual Transmission Control Unit (vTCU) software within a comprehensive, validated forward-looking SiL environment. This approach

Kengne Dzegou, Thierry Junior, Schober, Florian, Rebesberger, Ron, Henze, Roman

Impact of Water Injection on Emission Formation in an HVO-Fuelled NRMM Engine

2025-32-0067

11/03/2025

Water injection in diesel engines is a well-known method of lowering combustion temperatures and thus reducing nitrogen oxide (NOx) emissions. In this study, the influence of water injection in hydrogenated vegetable oil (HVO) operation on NOx formation, particulate emissions and ignition delay is analyzed in comparison to diesel operation on a John Deere JD4045 tractor engine. Both the fuel (HVO) and the water injection system were designed as ‘drop-in’ solutions that enable rapid implementation to reduce emissions, even in existing vehicle fleets. The standard engine control unit of the JD4045 engine was therefore used for the tests. A single water nozzle was installed downstream the charge air cooler to integrate a water injection system. The three operating points of interest were: (1) low speed and high load without exhaust gas recirculation (EGR), (2) high EGR rates at low speed and medium load and (3) the engine's ‘sweet spot’ regarding the emission-tradeoff at high speed and

Fuhrmeister, Jonas, Mayer, Sebastian, Günthner, Michael

RDE Testing of Small Motorcycle in Indian Road Conditions and Study the Impact of Instrumentation on Emission and Fuel Economy

2025-32-0075

11/03/2025

This paper presents measurement results of emissions and fuel economy on real-world driving of two-wheelers in India using a state-of-the-art FTIR PEMS technology. The study aimed to characterize the emissions profiles of a small motorcycle under typical Indian driving conditions, including congested urban traffic and highway driving. This is the continuation of the study conducted previously on bigger motorcycle using gas analyzer [1], with necessary adaptations to suit the specific conditions of Indian roads and traffic. Key parameters such as NOx, CO, CO2 and Fuel consumption were measured during real-world driving cycles and comparison is done with standard WMTC emission testing cycle. The findings of this study provide valuable insights into the actual on-road emissions of two-wheelers in India, which can be used to develop more accurate emission models and guide the development of cleaner and more efficient two-wheeler technologies. Key Considerations: Specifics of Indian Driving

Agrawal, Rahul, Jaswal, Rahul, Yadav, Sachin

Application of MAN Loop Scavenging in a 125 cm ³ Two-Stroke Racing Engine

2025-32-0029

11/03/2025

The use of MAN-type loop scavenging port arrangements in a 125 cc two-stroke racing engine is being investigated. These make it possible to provide larger cross-sections for the transfer ports, but at the expense of the exhaust port cross-section. The investigation is carried out using 1D calculations with GT-Suite. It is shown that significantly higher maximum outputs are possible in this way. However, this requires large exhaust widths, as otherwise the exhaust port is too small and the advantage of the larger transfer cross-section is overcompensated. Mixed forms between the original MAN loop scavenging and Schnürle loop scavenging can represent a good compromise. To improve the power characteristic vs. speed, which is influenced negatively by the higher maximum outputs, optimizations of port heights and exhaust pipe dimensions are carried out. A configuration with the same maximum output as the basis but a wider power band is also shown. One open point is the quality of the

Eilts, Peter

Design and Development of a Novel Automatic Powershift Transmission for Battery-Electric Vehicles

2025-32-0096

11/03/2025

The increasing adoption of battery-electric propulsion in two- and 3-wheelers, small cars, and four-wheeled delivery vehicles has created a growing demand for technological advancements to improve their autonomy. Due to cost and weight constraints, these vehicles cannot incorporate highly sophisticated electric motors, as seen in the premium car sector. Therefore, achieving the best possible efficiency in urban and extra-urban commuting requires innovative solutions. One promising approach is the integration of a two-speed transmission into the drivetrain, which allows for load point shifting within the electric motor’s operating map. This strategy significantly reduces energy consumption while maintaining optimal performance. The presented research focuses on the design and development of a simple, cost-efficient two-speed transmission that provides a viable alternative to direct drive systems. While direct drive configurations are highly efficient, they often lack flexibility in

Tromayer, Juergen, Stückler, David, Kirchberger, Roland

Torque Transfer Response Enhancement on the DCT with Estimated Hydraulic Pressure in the Clutch Piston Chamber

2025-32-0083

11/03/2025

The torque transfer response to rider throttle operation contributes to vehicle control in motorcycles equipped with a DCT (Dual Clutch Transmission). The clutch response is a key parameter to enhance torque transfer response. We have developed three new ECU (Electric Control Unit) control methods to enhance the clutch response on the DCT. The DCT clutch transfers torque by controlling the contact force between the clutch discs and the clutch plates. It is desirable to measure the hydraulic pressure value directly from the clutch piston chamber to control the contact force. However, since the clutch piston is a rotating body, it is impractical to place a hydraulic pressure sensor on it. Therefore, the hydraulic pressure sensor is placed along the clutch control oil line at the existing DCT system. Consequently, when oil flows in the oil line, pressure loss in the oil line causes a deviation between the hydraulic pressure sensor value and the clutch piston chamber pressure value, which

Takahashi, Kosaku

Transient Helium Jet Evolution Using High Speed Schlieren Imaging

2025-32-0057

11/03/2025

The accelerating global shift towards decarbonised energy systems has positioned hydrogen as a highly promising carbon-free fuel. This study comprehensively investigates the macroscopic characteristics and temporal evolution of vortex ring trailing helium jets, serving as a surrogate for hydrogen, injected into a quiescent ambient environment using high-speed Schlieren imaging. This research addresses critical insights into fuel-air mixing dynamics essential for optimising hydrogen direct injection (DI) internal combustion engines. Analysis of helium jet tip’s topology revealed a three-stage evolution from an initial pressure-insensitive phase, dominated by pressure wave structures, to a momentum-driven, vortex-dependent growth stage, then to a fully developed stage. Specifically, the lower-pressure cases showed increased Kelvin-Helmholtz instability and distinct head vortex pinch-off at the final stage. Jet tip velocities transitioned from initial high, rapid pressure wave development

Dong, Shuo, Shi, Hao, Zhang, Gengxin, Feng, Yizhuo, Lu, Enshen, Wang, Xinyan, Zhao, Hua

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