I-DSI

The L-series is a compact 4-cylinder engine created by Honda, introduced in 2001 with the Honda Fit. It has 1.2, 1.3 and 1.5 litre displacement variants, which utilize the names L12A, L13A, and L15A. Depending on the region, these engines are sold throughout the world in the 5-door Honda Brio Fit/Jazz hatchback Honda Civic and the 4-door Fit Aria/City sedan (also known as Fit Saloon). They are also sold in the Japanese-only Airwave wagon and Mobilio MPV.

Two different valvetrains are present on this engine series. The L12A, L13A, and L15A use (Japanese: ), or “intelligent Dual & Sequential Ignition”. i-DSI utilizes two spark plugs per cylinder which fire at different intervals during the combustion process to achieve a more complete burn of the gasoline. This process allows the engine to have more power while keeping fuel consumption low, thanks to the better gasoline utilization. Emissions are also reduced. The i-DSI engines have two to five valves per cylinder and a modest redline of only 6,000 rpm, but reach maximum torque at mid-range rpm, allowing for better performance without having to rev the engine at high speeds.

The other valvetrain in use is the VTEC on one of the two varieties of the L15A. This engine is aimed more at performance than efficiency with a slightly higher redline with 4 valves per cylinder, which reaches peak torque at higher rpm. However, it still offers a good combination of both performance and fuel efficiency. Both the i-DSI and VTEC have relatively high compression ratios at 10.8:1 and 10.4:1, respectively.

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Wikipedia