Japanese carmakers are looking to further improve gasoline engine efficiency and output to enable conventional automobiles compete with electric and eco-friendly powered vehicles, reports Nikkei Asian Review.
Mazda is reported to be adding variable displacement and mild hybrid systems to its current engines at the end of 2017. The variable displacement technology idles some of the engines cylinders when they are not needed and will be applied to larger engines found in Mazda’s CX-5 sport utility vehicle and other models. Mild hybrid systems incorporate a small electric motor to support the gasoline engine, decreasing engine load, and will be employed in a variety of models. The addition of these systems is reported to improve fuel economy by around 10%.
Nissan has reported plans to install variable-compression turbo engines in its Infiniti brand in 2018, with a view to expanding the technology to cover the entire Nissan range in future. An engine typically has a fixed compression ratio of around 10-1 to compress the gasoline-air mix in cylinders. Nissan’s variable-compression engine can change the top dead centre of piston movements to result in ratios ranging between 8-1 and 14-1.
Higher compression ratios raise combustion efficiency but can also increase the likelihood of engine knock, in which abnormal combustion causes body vibrations. The variable-compression engine will select the optimal compression ratio while balancing fuel consumption and output. The company has stated that it expects to see a 27% rise in fuel efficiency as a result of the change.
Toyota Motors has also announced its plans to roll out a powertrain this year which will improve fuel economy by around 20%, through better combustion efficiency and reduced components. Toyota has said it expects to use this type of powertrain in over 60% of its products by 2021, and is considering supplying the system to other companies.
Despite the steady increase in electric and hybrid engine manufacture, a report by IHS Automotive has predicted that in 2028 gasoline engines will still account for 48% of automobile power sources, with diesel engines at 12%.