VTEC in motorcycles

Apart from the Japanese market-only Honda CB400SF Super Four HYPER VTEC, introduced in 1999, the first worldwide implementation of VTEC technology in a motorcycle occurred with the introduction of Honda's VFR800 sportbike in 2002. Similar to the SOHC VTEC-E style, one intake valve remains closed until a threshold of 7000 rpm is reached, then the second valve is opened by an oil-pressure actuated pin. The dwell of the valves remains unchanged, as in the automobile VTEC-E, and little extra power is produced but with a smoothing-out of the torque curve. Critics maintain that VTEC adds little to the VFR experience while increasing the engine's complexity. Honda seemed to agree as their VFR1200, a model announced in October 2009, came to replace the VFR800; which abandons the V-TEC concept in favour of a large capacity narrow-vee "unicam" (i.e. sohc) motor.

AVTEC

The AVTEC (Advanced VTEC) engine was first announced in 2006. It combines continuously variable valve lift and timing control with continuously variable phase control. Honda originally planned to produce vehicles with AVTEC engines within next 3 years.

Although it was speculated that it would first be used in 2008 Honda Accord, the vehicle instead utilizes the existing i-VTEC system.

A related US patent (6,968,819) was filed in 2005-01-05.

i-VTEC i

It is a version of i-VTEC with direct injection.

It was first used in 2003 Honda Stream

i-VTEC with Variable Cylinder Management (VCM)

In 2003, Honda introduced an i-VTEC V6 (an update of the J-series) that includes Honda's cylinder deactivation technology which closes the valves on one bank of (3) cylinders during light load and low speed (below 80 km/h (50 mph)) operation. According to Honda "VCM technology works on the principle that a vehicle only requires a fraction of its power output at cruising speeds. The system electronically deactivates cylinders to reduce fuel consumption. The engine is able to run on 3,4, or all 6 cylinders based on the power requirement. Essentially getting the best of both worlds. V6 power when accelerating or climbing, as well as the efficiency of a smaller engine when cruising." The technology was originally introduced to the US on the Honda Odyssey minivan, and can now be found on the Honda Accord Hybrid, the 2006 Honda Pilot, and the 2008 Honda Accord. Example: EPA estimates for the 2011 (271hp SOHC 3.5L) V6 Accord are 24mpg combined vs. 27 in the two 4 cylinder equipped models.

i-VTEC VCM was also used in 1.3L 4-cylinder engines used in Honda Civic Hybrid.

K-series

The K-Series motors have two different types of i-VTEC systems implemented. The first is for the performance motors like in the RSX Type S or the Civic Si and the other is for economy motors found in the CR-V or Accord. The performance i-VTEC system is basically the same as the DOHC VTEC system of the B16A's; both intake and exhaust have 3 cam lobes per cylinder. However the valvetrain has the added benefit of roller rockers and continuously variable intake cam timing. Performance i-VTEC is a combination of conventional DOHC VTEC with VTC.

The economy i-VTEC is more like the SOHC VTEC-E in that the intake cam has only two lobes, one very small and one larger, as well as no VTEC on the exhaust cam. The two types of motor are easily distinguishable by the factory rated power output: the performance motors make around 200 hp (150 kW) or more in stock form and the economy motors do not make much more than 160 hp (120 kW) from the factory.

i-VTEC

(intelligent-VTEC)  has VTC (Variable Valve Timing Control) which introduced continuously variable timing of camshaft phasing on the intake camshaft 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 2002 Honda CR-V.

VTC controls the timing of valve lift and the timing of valve duration are still limited to distinct low- and high-RPM profiles, but the timing of the intake camshaft is now capable of advancing between 25 and 50 degrees (depending upon engine configuration) during operation. The timing of the VTC intake camshaft phasing 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. There are two types of i-VTEC K series engines which are explained in the next paragraph.

3-Stage VTEC

3-Stage VTEC is a version that employs 3 different cam profiles to control intake valve timing and lift. Due to this version of VTEC being designed around a SOHC valve head, space was limited and so VTEC can only modify the opening and closing of the intake valves. The low-end fuel economy improvements of VTEC-E and the performance of conventional VTEC are combined in this application. From idle to 2500-3000RPM, depending on load conditions, one intake valve fully opens while the other opens just slightly, enough to prevent pooling of fuel behind the valve, also called 12 valve mode. This 12 Valve mode results in swirl of the intake charge which increases combustion efficiency resulting in improved low end torque and better fuel economy. At 3000-5400 RPM, depending on load, one of the VTEC solenoids engages which causes the 2nd valve to lock onto the first valve's camshaft lobe. Also called 4 valve mode, this method resembles a normal engine operating mode and improves the mid-range power curve. At 5500-7000 RPM, the second VTEC solenoid engages (both solenoids now engaged) so that both intake valves are using a middle, third camshaft lobe. The third lobe is tuned for high performance and provides peak power at the top end of the RPM range.