The i stands for intelligent : i-VTEC is intelligent-VTEC. Honda introduced many new innovations in i-VTEC, but the most significant one is the addition of a variable valve opening overlap mechanism to the VTEC system. Named VTC for Variable Timing Control, the current (initial) implementation is on the intake camshaft and allows the valve opening overlap between the intake and exhaust valves to be continously varied during engine operation. This allows for a further refinement to the power delivery characteristics of VTEC, permitting fine-tuning of the mid-band power delivery of the engine.
At the moment, i-VTEC is only implemented in the relatively low specific power output engine of the new JDM Honda STREAM van. Used in the 2.0l DOHC i-VTEC engine, it allows Honda to boost low-end and mid-range power of that engine, a characteristic very desirable for that model. In my opinion, VTC is the most significant innovation that Honda introduced to i-VTEC. Other important innovations includes the changing of the engine orientation (as well as its rotation direction). i-VTEC engines are mounted such that the intake valves faces the front of the vehicle and the exhaust valves the rear, just like the Japanese Grand-Touring Championship racing cars. Other improvements are in the important areas of fuel economy and emissions.
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