Next Generation Environmental Engine
Simple Engine with Excellent Potential
In February 2010 we announced a plan to develop a next generation environmental engine for commuters by 2015, with the goal of 50% percent reduction in fuel consumption compared to 2008 levels. The "Nozza Grande" launched in Vietnam in August this year was the first model fitted with this engine.
We asked Mr. Suzuki from the 1st Engine Development Division, who has been with this project from its inception, to tell us the story of the development of this engine.
The development theme of 50% increase in fuel efficiency was something of a scale unheard of before this project. With this in mind, in addition to MC department, technicians were assembled from the Automotive, Marine and Technology departments along with analysis specialists, to make a start on this new independent project.
The team decided on "A no-frills engine not reliant on devices" as their basic development concept. It was also decided that the development process would be undertaken with an unwavering dedication to the highest principles. For example, when something is designed with a certain purpose it doesn't always perform as expected when tested. In these cases, rather than just say "Well the results are what they are" and carry on regardless, we decided to follow our key principle of thoroughly analyzing the cause of why the result was different to what we expected, even if it took extra time to do so.
We also focused on a higher benchmark than ever before. The normal approach would be based on the chassis, conducting performance research comparing competitors' products. However, this time we undertook a comprehensive analysis, removing the engine to look at how the fuel-air mixture was burning in the combustion chamber, and how much out-put was affected by mechanical loss leading up to final output.
In this way, our development process was a completely different approach but as we were making an engine for a commuter based vehicle, there were budget limitations as well. Early on, we set a detailed budget allocated to every 1% of fuel efficiency improvement.
Combustion Improvement, Increased Cooling Capacity, Mechanical Loss Reduction
For the development of this engine, the key factor has been combustion improvement. Specifically, we have made the compression ratio (CR) significantly higher than usual. An air-cooled engine typically has a CR of 9 but we set the ratio at 11, around the same level as a water cooled engine. In fact this higher compression ratio allowed for high torque, giving a comfortable ride, optimum combustion and an improvement in fuel efficiency.
However, if the compression ratio gets too high, the temperature within the combustion chamber becomes too hot, causing the fuel-air mixture to burn spontaneously before igniting correctly, resulting in a knocking effect. To counter this, we devised ways to improve cooling capabilities wherever we could. One way was by increasing the number of fins, which are very important for cooling. But due to limited space, we had to make each fin extremely thin in order to fit them in. This required the cooperation of our manufacturing division who solved the problem for us using vacuum suction and die casting techniques. Also, in order to provide enough cool air, we tested fans and ducts (air pathways) in order to achieve their optimal configuration.
In terms of combustion speed, we could implement revisions by utilizing analytical techniques and simulations. Generally speaking, fuel efficiency increases the faster the combustion speed. However after a certain point, fuel efficiency decreases and the engine noise just gets louder.Analyzing the combustion speed for the optimum balance of fuel consumption and noise、we realized that our engine combustion to date had been too fast. Accordingly, we made modifications to port configurations and other areas in order to adjust the combustion speed. As a result, fuel efficiency improved and the noise problem was solved.
Further to improving fuel efficiency, we also channeled our efforts into the important matter of reducing mechanical loss. To achieve optimum power from the combustion in the chamber, we carefully scrutinized any loss coming from metal joints. For example, we checked if we had the ideal piston ring tension. If it was too loose, oil consumption increased, but if it was too tight then friction increased. We also took time to verify if each item such as belt tension, oil seal fastening method, and bearing size were at their optimum capacity.
Making a higher dimension of tuning possible with one base engine
As a result of these efforts, we were able to create a no-frills engine with the highest level fuel efficiency in its class. "No-frills" means that it has high potential to evolve. For example, with this engine as the base, by just changing three things such as the air intake, muffler, and camshaft design, it is possible to achieve a higher dimension of tuning for performance, fuel efficiency, and a cleaner environment. Normally building an engine with different characteristics requires making a wide range of new parts, so being able to make a multiple of variations from one base engine allowed for considerable cost savings. I believe that such an engine is in fact the ideal platform.
The Nozza Grande model launched in Vietnam in August this year was fitted with this engine. This engine represents the ideology of Blue Core which "strives to take riding enjoyment, fuel efficiency and environmental performance to all-new levels".
With this project, I have confirmed my feeling that it is extremely important to have a high level of principles and integrity in simple engine development. Particularly when we consider the necessity to meet new environmental standards, it is essential to have simple engines with high potential. This is because without this ability we would need more manpower and money to be able to meet each change in standards.
Regarding our development staff, we not only gathered experienced veterans but purposely included young technicians as well. Because of this, we have been able to create an excellent engine and at the same time, grow the abilities of our younger technicians. I feel that this blend of youth and experience will become a model for future development teams.