Honda takes next steps in its downsizing strategy

Honda is working on a small displacement turbocharged engine based on its 1.5-litre gasoline direct-injection engine. The firm has not followed the downsizing trend but pressure to reduce fuel consumption is changing that.

The company has so far relied on variable valvetrains and mild hybrid systems to make its smaller gasoline engines more efficient but this may not be enough to meet Europe's increasingly stringent CO₂targets or CAFE regulations in the US. The 2.0-litre boosted engine in the next Civic Type R suggests that the company will eventually make downsized engines a mainstream product.

Honda's chief engineer for R&D, Akiyuki Yonekawa, said: “By adopting side direct-injection we can have use 28mm intake valves and 25mm exhaust valves. This combustion chamber specification has high output potential.”

The engine is based on the latest 1.5-litre VTEC four-cylinder twin-cam 16V unit used in the B-segment Jazz, known as the Fit in Japan and the US. The small 73mm bore has been retained to ensure maximum efficiency in production, while the 80mm stroke is the same as the 1.3-litre engine.

The high tumble intake ports were optimised to to reduce wall wetting, and therefore fuel consumption and emissions – this is usually more challenging with side-mounted injectors than with centrally-mounted injectors.

Honda has also looked at many different injector spray forms using optical engine analysis. The engine meets Euro 5 emissions regulations. Yonekawa said that it should also meet Euro 6b particulate number limits, although further development will be needed for Euro 6c.