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Tuesday, October 9, 2007

VTEC vs. VVEL

Here we have a clip of the VTEC acceleration vs. the VVEL acceleration. Basically shows why those little Honda cars are more fun drive. They're lightweight, rev-happy and has a lot more "spunk" if you will.

While the Infiniti's are heavier, and provides a smoother, but obviously slower acceleration throughout the RPM range.

VTEC


VTEC (Variable Valve Timing and Lift Electronic Control) is a valvetrain system developed by Honda to improve the volumetric efficiency of a four-stroke internal combustion engine.

This system uses two camshaft profiles and electronically selects between the profiles. This was the first system of its kind. Different types of variable valve timing and lift control systems have also been produced by other manufacturers (MIVEC from Mitsubishi, VVTL-i from Toyota, VarioCam Plus from Porsche, VVL from Nissan, etc).

It was invented by Honda R&D engineer Ikuo Kajitani.[1] It can be said that VTEC, the original Honda variable valve control system, originated from REV (Revolution-modulated valve control) introduced on the CBR400 in 1983 known as HYPER VTEC.

VVEL



Nissan Variable Valve Event and Lift (commonly known as VVEL) is an automobile variable valve timing technology developed by Nissan.
Nissan VVEL was introduced with the Nissan_VQ_engine VQ37VHR in 2007 on the Infiniti_G37. VQ37VHR motor specs: 11.0:1 CR, 95.5mm bore, 86mm stroke, 7500rpm redline.

A rocker arm and two types of links close the intake-valves by transferring the rotational movement of a drive shaft with an eccentric cam to the output cam. The movement of the output cam can be varied by rotating the control shaft within the DC motor and changing the fulcrums of the links. This makes a continuous adjustment of the valve lift amount possible. C-VTC and VVEL together control the valve phases and its valve events and lifts, allowing free-control of the valve timing and lift. This results in more efficient airflow through the cylinder and significantly improves responsiveness, optimizing the balance between power and environmental performance.


It functions similarly to BMW's Valvetronic system. The BMW system has more mass & friction so maximum rpm is limited. VVEL responds 32% quicker than Valvetronic and is 20% smaller and uses 52% less parts per cylinder.
Similar functioning systems have been announced by Honda (Advanced VTEC or AVTEC) and Toyota (Valvematic). The latest Toyota_ZR_engine 3ZR-FAE uses valvematic but like the BMW, rpm is limited.