Turbocharging is a common and simple method to utilize the exhaust heat of an internal combustion engine. However, conventional turbocharging exhibits the drawback of exhaust gas backpressure and thus increased residual gas mass in the cylinder. A promising concept to increase optimum efficiency is found in the TwinAV concept, which assigns divided exhaust valve cam timing and exhaust manifold configuration. This concept is hypothesized to reduce the static backpressure in the gas exchange loop and the residual exhaust gas amount in the gas exchange phase. In this article, a 1D simulation model was adapted to an existing 4-cylinder gasoline TC engine. Subsequently, the engine concept was applied to this engine model, whereas the focus was to achieve an engine layout for the entire engine speed range applicable for use in passenger vehicles. The results were compared at the full RPM range. Also, a load variation was conducted and benchmarked. The found results show an additional

Gotter, Andreas, Gotter, Alexander

Increasing the Efficiency of Hydrogen Direct Injection Internal Combustion Engines through the Use of Miller Cycles and Water Injection

03-19-01-0001

1/31/2026

Hydrogen-fueled reciprocating engines typically feature reasonable efficiencies and low engine-out emissions but low power density, compromising their utility and economics. Previous hydrogen engine research has found efficiency and anti-knock benefits when using either Miller cycles or water injection. This article therefore studies, for the first time, a directly injected (DI), spark-ignited, heavy-duty, turbocharged and hydrogen-fueled engine operated with both Miller cycles and water injection. Miller cycles, with either early or late intake valve closure, and water injection combine to achieve high engine efficiencies approaching 50%, which is significantly higher than the same engine with standard valve timing. The increased susceptibility of hydrogen autoignition in these Miller cycles is overcome by water injection, which simultaneously increases the charge density, counteracting both lean-burn hydrogen’s and Miller cycles’ commonly observed power loss. This demonstrates that

Mortimer, Joel, Poursadegh, Farzad, Brear, Michael, Yang, Yi

Evaluation of Intercooler Effectiveness with No Fan, Single Fan, and Dual Fan: A Simulation and Experimental Study

2026-26-0579

1/16/2026

Turbochargers play a crucial role in modern engines by increasing power output and fuel efficiency through intake air compression, thereby improving volumetric efficiency by allowing more air mass into the combustion chamber. However, this process also raises the intake air temperature, which can reduce charge density, lead to detonation, and create emissions challenges—such as smoke limits in diesel engines and knock in gasoline spark-ignited (GSL) engines. To mitigate this, intercoolers are used to cool the compressed air. Due to packaging constraints, intercoolers are typically long and boxy, limiting their effectiveness, especially at low vehicle speeds where ram air flow is minimal. This study investigates the use of auxiliary fans to enhance intercooler performance. Two methodologies were adopted: 1D simulation using GT-Suite and experimental testing on a vehicle under different fan configurations—no fan, single fan, and dual fans (positioned near the intercooler inlet and outlet

Patra, Somnath, Hibare, Nikhil, Ganesan, Thanigaivel, Gharte, Jignesh Rajendra

Experimental Evaluation of Energy and Exergy of Hydrogen, CNG and Gasoline Fuelled High-Speed Spark Ignition Engine

2026-26-0258

1/16/2026

The maximum power is recorded with Gasoline than CNG and Hydrogen fuel. The maximum exergy and energy efficiency is with Hydrogen, followed by CNG and then Gasoline. Hydrogen fuel has a maximum potential to convert into energy. The maximum energy destruction of 48.7kW for gasoline fuel at 3000 rpm and followed by CNG and hydrogen. The maximum entropy generation of 85.5 W/K with Gasoline and 60.72 W/K and 29.39W/K for CNG and hydrogen engine respectively at 10000 rpm. The entropy generation rate increase with engine speed. The highest rate of heat release is from hydrogen fuel, followed by Gasoline and CNG.

Shinde, Apurwa Balasaheb, Kadam, Tushar, karunamurthy, K, SHINDE, DR BALU

Development of an Oxy-Hydrogen Engine for Power Generation Application Using Simulation and Experiment

2026-26-0260

1/16/2026

Hydrogen is a zero-carbon fuel suitable for the de-carbonization of power generation and the industrial sector. Green hydrogen produced via the electrolysis of water is the most sustainable fuel to achieve a net-zero carbon economy. Oxy-hydrogen (hydrogen and oxygen) generated onsite from the electrolyzer can be fed to engine with the intake air to enhance power and combustion efficiency with near-zero exhaust emissions. In this study, a 15 kVA two-cylinder natural gas spark-ignition generator set was used. The engine was retrofitted to operate on an oxy-hydrogen-air mixture. A maximum of 43% of rated engine load was achieved during the preliminary experiments. GT-Power software was used to calibrate the 1D model using experiment data and generate the burn profile of oxy-hydrogen-air mixture. The calibrated and validated 1D model was used for further predictive simulations. The power limiting factors were identified via simulations for flow and power improvement. The simulations

Marwaha, Akshey, Tule, Shubham, Mishrikotkar, Prasad, Aghav, Yogesh

Performance and Emission Characteristics of a Lean-Boosted Direct Injection Hydrogen Combustion System for Retrofitting Heavy Duty Diesel Engines

2026-26-0268

1/16/2026

To address the imperative for decarbonizing the heavy-duty transport sector and advancing sustainable energy solutions, this paper presents a novel lean-boosted Direct Injection (DI) Hydrogen Internal Combustion Engine (H2 ICE) combustion system. This system is developed to retrofit existing flat-deck Diesel engines, offering a viable pathway towards drastically reduced emissions. Building on consolidated expertise from prior production-oriented Port Fuel Injection H2 engine development (DUMAREY 6.6ℓ V8), this research focuses on leveraging the distinct advantages of DI for hydrogen. An experimental assessment, supported by 1D and 3D-CFD analyses, demonstrates the system's capability to achieve highly efficient operation in Spark Ignition (SI) mode under ultra-lean and EGR-diluted conditions. The study confirms the elimination of combustion anomalies such as backfiring, pre-ignition, and knock, while achieving ultra-low engine-out NOx emissions and near-zero CO2, HC, CO, and PM. The

Gessaroli, Davide, Golisano, Roberto, Pesce, Francesco, Boretto, Gianmarco, Accurso, Francesco

3D CFD Combustion Evaluation of Hydrotreated Vegetable Oil (HVO) as a Potential Alternate Fuel for the Future CI Engines

2026-26-0113

1/16/2026

Transportation industry is facing a growing challenge to reduce its carbon footprint and utilize the carbon neutral, more environmentally sustainable fuels to comply with the goal of carbon neutrality. Implementation of carbon free fuels such as Hydrogen, Ammonia and low carbon fuels such as Methanol, Ethanol can significantly reduce the greenhouse gas emissions, but these fuels are suitable for SI engine architecture due to their high-octane ratings. Hydrotreated Vegetable Oil (HVO) is one of the few fuel solutions available today with a high Cetane rating (70-80), that can be used as a drop-in fuel in the existing CI engines, with minimal modifications. The main constituent of HVO is pure alkane and it can be produced from feedstocks such as vegetable oils, animal fats, various wastes and by-products. A closed cycle 3-D CFD combustion simulation using a detailed chemistry-based solver has been conducted with the HVO, on a three cylinder, naturally aspirated water-cooled CI engine at

Tripathi, Ayush, Mukherjee, Nalini, Nene, Devendra

Development of High BMEP Natural Gas Engine with Knock Mitigation

2026-26-0121

1/16/2026

The stringent emission norms over the past few years have driven the need to use low-carbon fuels and after treatment technology. Natural gas is a suitable alternative to diesel heavy-duty engines for power generation and transportation sectors. Stoichiometric combustion offers the advantages of complete combustion and low carbon dioxide emissions. Turbocharging and cooled exhaust gas recirculation (EGR) technology enhances the power density along with reduced exhaust emissions. However, there are several constraints in the operation of natural gas spark ignition engine such as exhaust gas temperature limit of 780 °C, sufficient before turbine pressure for EGR drivability, boost pressure, peak cylinder pressure limit and knocking. These limits coulld restrict the engine BMEP (brake mean effective pressure). In the present study, tests were conducted on a V12, 24 liters, heavy duty natural gas fuelled spark ignition engine (600 HP) with different EGR and turbocharger configurations to

Khaladkar, Omkar, Marwaha, Akshey

Combustion Chamber Geometry Comparison in Natural Gas Engines under Conventional and Dethrottled Operation

2025-36-0217

12/18/2025

Growing interest in cleaner energy has spurred progress in engine technology, focusing on greater efficiency and lower emissions. Methane-based fuels, like compressed natural gas (CNG), have become an alternative for spark-ignition engines, especially in Brazil. Among performance strategies, dethrottled operation stands out by reducing intake restrictions and minimizing pumping losses, a major inefficiency in conventional spark ignition engines. This improves thermal efficiency and reduces both fuel consumption and emissions. This study experimentally examines the performance and combustion of a CNG-powered Hyundai HR 2.5 16V engine, converted from diesel to spark ignition with natural gas, comparing factory (omega) and custom (reentrant) piston geometries under both conventional and dethrottled modes. The research evaluates how piston design affects combustion stability, efficiency, and emissions across different load strategies. Tests were conducted at 7, 8, and 9 bar loads, as well

Silva, Cristian Douglas Rosa da, Garlet, Roberto Antonio, Dapper, Jackson Mayer, Fagundez, Jean Lucca Souza, Lanzanova, Thompson Diórdinis Metzka, Martins, Mario Eduardo Santos

Development of a Graphic Interface to Evaluate the Performance of a Hydrogen-Fueled Spark Ignition Engine

2025-36-0165

12/18/2025

In recent decades, interest in alternative fuels has grown exponentially. Hydrogen has been researched as total or partial substitutes for gasoline in light vehicles, showing great potential. However, this fuel has unique characteristics and properties that can bring improvements or limitations in engine performance. Therefore, a quick analysis of the pressure and HRR curve can highlight changes in combustion and performance. To this end, the aim of this work is to develop a visual interface generated by MATLAB capable of showing the performance parameters of a spark ignition engine when using hydrogen as fuel, initially. This graphic interface is supported with a zero-dimensional model based on the Wiebe function and Woschni correlation to estimating the pressure and HRR values. The interface is designed to receive operating conditions and geometry of the engine, as well as combustion angles. From the information entered, it is possible to visualize mass fraction burned, heat transfer

Rincon, Alvaro Ferney Algarra, Alvarez, Carlos Eduardo Castilla, Oliveira Notório Ribeiro, Jéssica

Combustion Chamber Pressure and Temperature Analysis Based on Heat Release Rate Parameters of a Spark Ignition Engine

2025-36-0082

12/18/2025

Internal combustion engines have been developed and widely used since the last century, and they continue to be extensively employed today. Engine development has progressed significantly, and due to the environmental impacts caused by their use, new technologies are being developed to reduce pollutant formation after the combustion process and to increase thermal efficiency. Computational modeling is a tool that has supported this development and can be categorized into three types: zero-dimensional, quasi-dimensional, and three-dimensional models. The 0D and 1D models offer a good balance between computational processing time and result uncertainty when compared to three-dimensional models. The Wiebe function is a simple analytical approach capable of describing the fuel burn rate in combustion engines. Previous studies have shown that applying this function yields results that accurately describe the apparent heat release rate in PFI engines.The present study aims to determine the

Souza Pereira, Felipe Augusto de, Araújo Moreira, Thiago Augusto de, Filho, Fernando Antônio Rodrigues

Effect of Ultra-High Fuel Injection Pressure on Combustion Characteristics, Engine Performance and Pollutant Emissions of a Multi-Cylinder Engine

2025-36-0212

12/18/2025

Antolini, Jácson, Zabeu, Clayton Barcelos, Pires, Gustavo Cassares, Polizio, Yuri

Optimization of Biogas Combustion in SI Engines Applied to the Pre-Chamber Ignition System

2025-36-0209

12/18/2025

Siqueira, Caio Henrique Moreira, Ázara, Luiz Eduardo Martins, Ribeiro, José Vitor Puttini, Soares, Gabriel Faria, Silva, Fábio Moreira, Alvarez, Carlos Eduardo Castilla

Letter from the Guest Editors

04-19-01-0001

12/10/2025

Letter from the Guest Editors

Assanis, Dimitris, Cho, Seokwon, Lawler, Benjamin, Pintor, Dario Lopez

A Review of the Application and Research Progress of Turbulent Jet Ignition Technology

03-18-08-0047

12/3/2025

For the sustainable development of human society, energy saving, emission reduction, and carbon reduction are urgent challenges to be addressed in the energy industry. As a power device for energy conversion in the transportation sector, the internal combustion engine also needs to enhance its thermal efficiency while cutting pollutant emissions. To meet the current stringent requirements, lean combustion has been widely studied as an effective strategy. However, the ignition difficulty resulting from lean burn needs to be addressed. As a high-energy ignition system, the prechamber turbulent jet ignition can accelerate in-cylinder combustion, thereby enhancing engine efficiency and reducing emissions. Thus, it is considered a promising technology. This review reveals efforts to apply prechamber ignition systems to optimize combustion in the engine characterized by low-carbon fuels and low-emission features. First, this article briefly introduces the evolution of the prechamber

Bai, Xiujuan, Zheng, Dayuan

Visualization of Ammonia Engine by Pre-Chamber Igniter

2025-01-0530

11/25/2025

Ammonia is considered more and more as a promising carbon-free fuel for internal combustion engines to contribute to the decarbonization of several sectors where replacing conventional engines with batteries or fuel cells remains unsuitable. However, ammonia properties can induce some challenges for efficient and stable combustion. This study investigates the use of an active pre-chamber ignition system fueled with hydrogen and compares it to conventional spark ignition, with a focus on lean limit operation and early flame development. Experiments were conducted on a single cylinder optical engine with a compression ratio of 9.5, equipped with a quartz window in the piston for natural flame luminosity imaging using a high-speed camera. The engine was fueled with a mixture of 95% ammonia and 5% hydrogen by volume. Ammonia was injected and mixed with air in the intake port while hydrogen was directly injected into the prechamber. As a function of the intake pressure (1.0, 0.9, 0.8, and

Rousselle, Christine Mounaim, Brequigny, Pierre, Gelé, Raphaël, Moreau, Bruno

Knock Phenomenon Investigation in SI Engine Fuelled with Ammonia-Hydrogen Mixture

2025-01-0532

11/25/2025

Ammonia has emerged as a compelling carbon-free alternative fuel for applications in sectors such as power generation and heavy-duty transportation, where thermal energy conversion plays a dominant role. Its potential lies in its high hydrogen content, carbon-free combustion, and the feasibility of large-scale storage and transport. However, ammonia’s combustion behavior poses significant challenges due to its low reactivity, characterized by a low laminar burning velocity, high autoignition temperature, and narrow flammability range. These properties hinder stable and efficient operation in conventional internal combustion engines. A common strategy to mitigate these limitations involves blending ammonia with hydrogen—often generated via on-board catalytic cracking of ammonia—which improves ignition and flame speed. Despite these benefits, the presence of hydrogen increases the risk of knock, particularly in high-compression-ratio engines designed to improve thermal efficiency. This

Hurault, Florian, Brequigny, Pierre, Foucher, Fabrice, Rousselle, Christine

Feasibility of Ammonia as a Spark-Ignition Engine Fuel: Strategies for Combustion Stability and Engine Efficiency

2025-01-0531

11/25/2025

Ammonia (NH3) is a promising energy carrier and a potentially alternative fuel to selected sectors due to its carbon-free nature and its relatively high energy density. However, its low reactivity and slow flame propagation pose significant challenges for a direct use in an internal combustion engine, and stable operation at all engine’s conditions. This study investigates three combustion strategies for utilizing NH3 in an adapted four-cylinder 2 L turbocharged, compression-ignition engine, adapted for spark-ignition (SI) operation. Initially, the engine was tested using pure ammonia as fuel, obtaining high efficiencies and acceptable stability at medium/high loads. Nevertheless, intense combustion instabilities could not be avoided below a minimum load level (which increases with engine speed), making engine operation unfeasible in approximately 30 % of its operating map. To address these limitations, two enhancement strategies are explored: Firstly, hydrogen (H2) doping pre-mixed

Karageorgiou, Dimitrios, Myslivecek, Matej, Gaillard, Patrick, Gomez-Soriano, Josep, González-Domínguez, David, Lujan, Jose, Alcarria Laserna, Gerardo

Development of a Comprehensive Predictive QD Knock Simulation Model for Hydrogen, Methanol, and an Ammonia–Hydrogen Blend

2025-01-0528

11/25/2025

To support the transition toward climate-neutral mobility and power generation, internal combustion engines (ICEs) must operate efficiently on renewable, carbon-neutral fuels. Hydrogen, methanol, and ammonia-hydrogen blends are promising candidates due to their favorable production pathways and combustion properties. However, their knock behavior differs significantly from conventional fuels, requiring dedicated simulation tools. This work presents a modeling framework based on quasi-dimensional (QD) engine simulation, including two separate knock prediction models. The first model predicts the knock boundary of a given operating point and combines an auto-ignition model with a knock criterion. The overall methodology was originally developed for gasoline and is here adapted to hydrogen, methanol, and ammonia-hydrogen blends. For this purpose, the relevant fuel properties were incorporated into the auto-ignition model, and a suitable knock criterion was identified that applies to all

Benzinger, Steffen, Yang, Qirui, Grill, Michael, Kulzer, Andre Casal, Plum, Lukas, Hermsen, Philipp, Günther, Marco, Pischinger, Stefan, Hurault, Florian, Foucher, Fabrice, Rousselle, Christine

Engine Power Test Code - Spark Ignition and Compression Ignition - As Installed Net Power and Torque Rating

J1349_202511 (Current)

11/19/2025

This SAE Standard is intended to provide a method to obtain repeatable measurements that accurately reflect true engine performance in customer service. Whenever there is an opportunity for interpretation of the standard, a good faith effort shall be made to obtain the engine’s typical in-service performance and avoid finding the best possible performance under the best possible conditions. Intentional biasing of engine component or assembly tolerances to optimize performance for this test is prohibited.

Engine Power Test Code Committee

Experimental Investigations on Lean Burn Spark-Ignition Engine Using Alcohol-Gasoline Blends

2025-28-0213

11/6/2025

Alcohol fuels are regarded as a feasible approach to address rising energy demands and reduce the dependency on fossil fuels, with ethanol and methanol emerging as a promising renewable fuel for spark-ignition engines. In this research work, tests were performed on a spark ignition engine altered from a diesel engine that employs ethanol/methanol-gasoline blend as fuel operating under lean conditions. The experiments were conducted at 10.5:1 compression ratio and 1500 rpm under full throttle condition with three fuel blends namely M10 (10% of methanol+ 90% gasoline), E10 (10% of ethanol+ 90% gasoline), E5M5 (5% of each ethanol and methanol+ 90% gasoline). Investigational results reveals that alcohol-gasoline blends displayed low COV of IMEP. Furthermore, the alcohol-gasoline mixtures enhanced the peak in-cylinder pressure owing to improved flame speed and flammability limits. Adopting lean-burn operation and high compression ratio can efficiently improve combustion attributes in an

Devunuri, Suresh, Porpatham, Dr. E

Measurement of the Liquid Fuel Film on the Combustion Chamber Wall of a Gasoline Engine using a Novel Capacitive Sensor

2025-32-0018

11/3/2025

The reduction of exhaust emissions and particulate matter from internal combustion engines remains a critical challenge, particularly under cold start and warm-up conditions, where a significant portion of total emissions is generated. In spark-ignition (SI) gasoline engines, the formation of liquid fuel films on intake ports wall, piston and cylinder wall surface significantly contributes to unburned hydrocarbon and particulate emissions. Also, the fuel film adhering to the wall can be a cause of the lubricating oil dilution. To address these issues, a novel capacitive sensor, fabricated using MEMS technology, was developed and applied to investigate the behavior of liquid fuel films formed inside the combustion chamber of a single-cylinder engine. The sensor detects changes in capacitance caused by fuel film adhesion to the sensor surface. The sensor was installed in a single-cylinder test engine along with a direct fuel injector allowing for the controlled formation of fuel films on

Kuboyama, Tatsuya, Nakajima, Takeru, Moriyoshi, Yasuo, Takayama, Satoshi, Nakabeppu, Osamu

Performance Prediction of a Two-Stroke Aviation S.I. Engine by Means 0D/1D Thermo-Fluid Dynamic Simulation Code

2025-32-0026

11/3/2025

Two-stroke engines represent an attractive solution for aviation industry applications (UAVs, VTOL aircraft, and ultralight aircraft) due to their compact size, high power-to-weight ratio, reduced number of moving parts, and the ability to operate with different fuels. This work presents a 0D/1D methodology for simulating the gas exchange, combustion, and unsteady flow of a two-stroke aviation engine. The scavenging and combustion processes, as well as the unsteady flow within the induction and exhaust systems, are investigated using a 0D/1D modeling approach. This study is motivated by the need to assess the accuracy of such models in predicting engine performance. For this purpose, the thermo-fluid dynamic code GASDYN has been applied and enhanced. The proposed 0D model is embedded into a 1D fluid-dynamic code for simulating the entire engine system. To characterize the baseline configuration, which includes tangential ports that facilitate a loop-scavenging process, computed results

Cerri, Tarcisio, Giussani, Alessandro, Lucchini, Tommaso, Marinoni, Andrea, Montenegro, Gianluca, Onorati, Angelo

Ca Additive and In-Cylinder Condition on Promotion of Abnormal Combustion in Supercharged SI Engine

2025-32-0004

11/3/2025

Recently, global warming is becoming seriously. In the field of internal combustion engine, the thermal efficiency has to improve in the practical use. One of the current trends with spark ignition engine (SI engine) is “downsizing” which is equipped supercharger with the downsized displacement. The downsizing engine is popular in the field of the SI engine. However, one of the problems is the abnormal combustion so called Low Speed Pre-Ignition (LSPI) [1]. The LSPI occurs the engine operation which is low speed and high load condition. It has to be avoided, because the SI engine is broken and the improvement of thermal efficiency is obstructed. A lot of researchers have been reported about the mechanism of LSPI [2, 3]. One of the sources of LSPI would be the lubricating oil droplets in cylinder. One of the methods to avoid LSPI, it has been adjusted the ingredients of oil additive in lubricating oil. The state of the art of lubricating oil standard has been established anti-LSPI

kitano, Kaito, Tanaka, Junya

Experimental Study of hCNG on Single Cylinder 395cc Spark Ignition Engine for Performance and Exhaust Emission

2025-32-0050

11/3/2025

There is growing demand for energy utilization due to stricter environmental emission norms to reduce greenhouse gases and other threats posed due to the emissions are major motivation factors for researchers to adopt on strategic plans to decrease the usage of energy and reduce the carbon contents of fuels, the usage of hydrogen or blend of hydrogen with CNG as a fuel in internal combustion engines is the best option. As hydrogen has lower volumetric energy density and higher combustion temperature, pure hydrogen-fueled engines produce lower power output and much higher NOx emissions than gasoline-fueled engine at stoichiometric air-fuel ratio. Blending of hydrogen with CNG provides a blended gas termed as hydrogen-enriched natural gas (hCNG). hCNG stands for hydrogen enriched compressed natural gas and it combines the advantages of both hydrogen and methane. The addition of Hydrogen to CNG has potential to even lower the CNG emissions and is the first step towards promotion of a

Syed, Kaleemuddin, Chaudhari, Sandip, Khairnar, Girish, Sajjan lng, Suresh

Study on Combustion Detection of a Spark-Ignition Engine with Fuel Variation Using Various Sensors

2025-32-0052

11/3/2025

The use of alternative fuels, such as biofuels and synthetic fuels in small mobility engines has become more common these days. Although these fuels contribute to the carbon neutrality, it is known that they do not have a certain fuel composition, which significantly affects the combustion characteristics of an engine, such as knocking and combustion duration. Therefore, to get the most out of these sustainable fuels, it is necessary to develop engine systems that are highly robust to variations in fuel composition. To achieve this goal, a method to sense fuel characteristics onboard using sensors already widespread in use or can be installed inexpensively is required. Although in-cylinder piezoelectric pressure sensors are useful for research in the laboratory, it is not suitable for the use in commercial engines because of its high cost. Therefore, the use of other sensors should be considered. The purpose of this study is to experimentally analyze what information related to

Hayashi, Kohei, Kim, Jihoon, Yamasaki, Yudai

Methodology of Minimum Energy Starting for SI Engine

2025-32-0090

11/3/2025

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

Study of Combustion Characteristics of a Two-Stroke Opposed Piston Engine using Low-Octane Fuels

2025-32-0028

11/3/2025

Various fuels are being considered as the next generation of carbon neutral fuels, including methanol, ethanol, and SAF. These have widely different ignition properties. Methanol and ethanol are high-octane fuels, so there are no major problems with their use in gasoline engines. However, SAF is a hydrocarbon with a large molecular weight, so it has a fundamentally low octane rating and is not easy to use in SI engines. In order to put carbon-neutral fuels of various properties into practical use, it is effective to develop a technology that allows fuels with low octane to be operated in SI engines. Therefore, in this study, basic research was conducted on the combustion of fuels with low octane using PRF fuel in opposed-piston engines. Opposed piston engines are characterized by their light weight due to the absence of a cylinder head, low S/V ratio due to the ultra-long stroke, reduced cooling loss due to the long stroke, and reduced vibration due to the offsetting of the

Yamazaki, Yoshiaki, Okawara, Ikumi, Liu, Jinru, Iijima, Akira

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