NISSAN TECHNOLOGY MAGAZINE

Reducing is evolving: Downsized Engine Combines Low Fuel Consumption and Power.

Generally we tend to think an engine is evolving if its getting larger, but actually there is another approach. We call this downsizing. Downsizing is now a major trend in the industry.

In recent years, car-makers have been adopting multiple strategies to make fuel consumption more efficient. And yet, in truth, just to make gas mileage better is a simple matter. All you have to do is cut the number of cylinders and the displacement in the engine. For example you could change a four cylinder engine to three cylinders and say 1.5-liter displacement to 1.2-liter. If there are less cylinders and cylinder capacity, the engine becomes lighter, which directly leads to lower fuel consumption. Also if we consider that the engine is a reciprocating machine, reducing the cylinders also then reduces the friction. Thus, the movement of the engine becomes more efficient and gas mileage is better.

The technology behind Downsizing:

How to make an engine that is smaller but without losing its driver performance? A Supercharger does this. A Supercharger is an air compressor that pumps pressurized air into an engine. The latest superchargers have enhanced turbine design and lowering drag and are in fact a core piece of technology behind environmentally friendly and enjoyable driving. This kind of supercharger helps to pump 1.5 liters of air into 1.2 liters engine.

Direct gasoline injection is also an important of the downsized engine. In previous cylinders, fuel is injected near to the cylinder and then pumped in. On the other hand, with a directly injected gasoline system, fuel is injected straight into the combustion chamber inside the cylinder. The merit of this is that then the gasoline vaporization cools the temperature inside the cylinder. In supercharger or turbocharger engines, the intake temperature is prone to heating up due to the air that is pumped into the cylinder at high pressure. It would conventionally then have to control the temperature by lowering the engine compression ratio. . However in the gasoline engine more pressure leads to the combustion temperature become too high giving you abnormal combustion and engine knock. Gasoline direct injection, though, has a cooling effect, so the super charger can pump in lots of air and burn off the fuel while still keeping the temperature from going too high. This means we can increase the compression ratio without adverse effects, which enhances both fuel mileage and the pleasure in driving experience.

Engine evolve for high fuel economy while retaining driving pleasure

The “protagonists” of the eco car movement could be said to be hybrid and EVs. There can be no doubt about this in the long term, but the truth is that hybrid cars have complex mechanisms that make them expensive, while electric vehicles require specialist social infrastructures to be put in place before they become truly widespread. If we consider the actual situation in any country or region, surely it is realistic to say that for now, gasoline engine vehicles will be mainly on the rise.

Our environmental concern like global warming cannot only tackled by spread of hybrid vehicles and EVs. It is also essential that we enhance gasoline engines in order to improve fuel efficiency. Nissan’s downsize engine combining both low fuel mileage and driving comfort is just an example of the innovative concepts surely soon to appear in the near future.