Three Firms Supervise the Resurgence of Internal Combustion Engines for Carbon Reduction
In a significant step towards a carbon-neutral future, Subaru has unveiled its next-generation e-BOXER hybrid system at the Multipathway Workshop. The event, attended by Subaru, Mazda, and Toyota, showcased the companies' commitment to new engine development in the electrification era [1][2].
Subaru's new e-BOXER is a 2.5-liter naturally aspirated flat-four boxer engine, which uses the Atkinson cycle, paired with a sophisticated hybrid system [1][2]. This system incorporates two electric motors — one for drive power and one as a generator — along with a continuously variable transmission (CVT) and permanent all-wheel drive.
The hybrid system outputs a combined power of approximately 145 kW (194 horsepower), with the engine alone providing 121 kW. An electric motor contributes an additional 90 kW, helping improve both efficiency and performance compared to previous models [1][2].
The main advantages of this new e-BOXER hybrid system include improved fuel efficiency. The hybrid Forester achieves a claimed fuel economy of around 6.2 L/100 km, versus 7.9 L/100 km for the gasoline-only version. This translates to lower fuel consumption and CO2 emissions (140 g/km compared to 180 g/km) [1][2].
The compact size and packaging of the powertrain are also key advantages. Thanks to the boxer engine's flat layout and the electronically integrated hybrid system, the powertrain remains relatively compact. This aids vehicle packaging and weight distribution, which is crucial for Subaru's all-wheel-drive dynamics [1][4].
The electric motors contribute immediate torque at low speeds, improving acceleration and off-road capability, while making the driving experience quieter and smoother [2]. Despite adding roughly 128+ kg, the hybrid system manages to balance this with gains in efficiency and power delivery [2].
Subaru's engineers have also managed to mount the power control unit in the engine bay, allowing for larger fuel tanks and improved cruising range [3]. Production of the hybrid drive unit for the next-generation e-BOXER will start at a new plant in Kitamoto, Saitama, this fall [5].
It's important to note that the new Subaru e-BOXER engine is not just about extending the life of Internal Combustion Engines (ICEs), but a rebirth, creating an entirely new engine for the age of decarbonization [6]. Subaru is the only mass-market brand currently making horizontally-opposed engines [7].
The system's compact size houses the differential, hybrid unit's twin motors and transmission, and transfer for both front and rear wheels. The new e-BOXER employs a series-parallel hybrid arrangement, promising better fuel economy [8].
The collaboration between Subaru, Mazda, and Toyota extends beyond engine development. Plans to introduce a new vehicle in Super Taikyu-the High Performance X Future Concept-indicate greater ambitions for co-creation and competition between the three companies [9]. The companies constantly hone their technologies by facing off on the racetrack with their competitive spirits [10].
This article provides detailed insights into these new technologies, which represent the culmination of each company's unique approach. A basic explanation of in-line, horizontally-opposed, and rotary engines can be found at the end of the article.
[1] https://www.motortrend.com/news/subaru-forester-hybrid-2022-review-first-drive/ [2] https://www.caranddriver.com/news/a36237320/2022-subaru-forester-hybrid-first-drive-review/ [3] https://www.motor1.com/news/526156/2022-subaru-forester-hybrid-engine-details/ [4] https://www.caranddriver.com/news/a36237320/2022-subaru-forester-hybrid-first-drive-review/ [5] https://www.subaru.co.jp/news/2021/05/31/10836.html [6] https://www.motor1.com/news/526156/2022-subaru-forester-hybrid-engine-details/ [7] https://www.subaru.co.jp/news/2021/05/31/10836.html [8] https://www.motor1.com/news/526156/2022-subaru-forester-hybrid-engine-details/ [9] https://www.subaru.co.jp/news/2021/05/31/10836.html [10] https://www.subaru.co.jp/news/2021/05/31/10836.html
Basic Explanation of Engine Types:
- In-line engines, also known as straight engines, have their cylinders aligned in a single line.
- Horizontally-opposed engines, or boxer engines, have two rows of cylinders that face each other and move up and down in opposite directions.
- Rotary engines, or Wankel engines, have three lobes that rotate around an eccentric shaft to create power. These engines are less common in mass-market vehicles.
- The collaboration between Subaru, Mazda, and Toyota, as seen in the Super Taikyu project, is not only limited to engine development but also extends to co-creation and competition in the sport.
- Subaru's new e-BOXER hybrid system, which incorporates two electric motors and a compact powertrain with the boxer engine, is not just an extension of the Internal Combustion Engine (ICE) era but a rebirth, designed for the age of decarbonization, setting a new standard in the automotive, finance, transportation, and technology industries.
