i-VTEC (intelligent-VTEC)  introduced continuously variable camshaft phasing on the intake cam of DOHC VTEC engines. The technology first appeared on Honda’s K-series four cylinder engine family in 2001 (2002 in the U.S.). In the United States, Honda first debuted the technology on the 2003 Honda Civic Si EP3 with the economy version.

Valve lift and duration are still limited to distinct low- and high-RPM profiles, but the intake camshaft is now capable of advancing between 25 and 50 degrees (depending upon engine configuration) during operation. Phase changes are implemented by a computer controlled, oil driven adjustable cam gear. Phasing is determined by a combination of engine load and rpm, ranging from fully retarded at idle to somewhat advanced at full throttle and low rpm. The effect is further optimization of torque output, especially at low and midrange RPM.

i-VTEC is VTEC with VTC added. K20A uses a combination of VTEC-E and power-VTEC that switches between 12-valve economy mode and a 16-valve mode with a separate wild intake cam. VTC complements this VTEC variation. For the K20A engine however, outright power is not the sole objective of iVTEC, the other important parameters of fuel economy and emissions has been given equally important footing, a direction that Honda has always promoted in the past. This impossible balance of power and economy has previously only been realizeable in Honda’s D15B 3-stage VTEC first used on the previous generation EK3 (and the D17A on the current Civic).

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