VTEC is one of Honda's greatest invention.

Thus Honda invented VTEC which allows it to extract turbo level specific output from its engines without having to suffer from the disadvantages of turbocharging (though VTEC introduces disadvantages of its own).

History

The first experimentation with variable valve timing and lift was performed by General Motors. GM was actually interested in throttling the intake valves in order to reduce emissions. This was done by minimizing the amount of lift at low load to keep the intake velocity higher, thereby atomizing the intake charge. GM encountered problems running at very low lift, and abandoned the project.

The first functional variable valve timing system, including variable lift, was developed at Fiat. Developed by Giovanni Torazza in the 1970s, the system used hydraulic pressure to vary the fulcrum of the cam followers. The hydraulic pressure changed according to engine speed and intake pressure. The typical opening variation was 37%.

The next big step was taken by Honda in the late 1980s and 90s, where Honda began by experimenting with variable valve lift. Pleased with the results, engineers took the knowledge and applied it to the B16A engine, fitted to the 1989 EF9 Honda Civic. From there it has been used in a variety of applications, from sport to utility, by many different auto makers.

In the year 1992, BMW introduced VANOS, their version of a variable valve timing system, on the BMW M50 engine used in the 3 Series. VANOS significantly enhances emission management, increases output and torque, and offers better idling quality and fuel economy. The latest version of VANOS is double-VANOS, used in the new M3. Double-VANOS adds an adjustment of the intake and outlet camshafts.

One thing that separates the BMW variable timing from what Honda developed is that VANOS provides stepless adjustments to the valve timing throughout a rpm regime to provide optimum timing at all engine speeds within that regime. Honda's VTEC triggers a single step change at in the timing when the engine speed reaches a preset rpm (this rpm occurs near high rpm ranges).

Variable valve timing was the sole domain of overhead cam engines until 2005, when General Motors began offering the LZE and LZ4, pushrod V6 engines with VVT. For the 2006 model year, General Motors will introduce the Vortec 6200, the first mass-produced pushrod engine with variable valve timing.