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Variable valve lift (VVL) is an automotive piston engine technology which varies the height a valve opens in order to improve performance, fuel economy or emissions. There are two main types of VVL: discrete, which employs fixed valve lift amounts, and continuous, which is able to vary the amount of lift.
The timing, duration and lift of these valve events has a significant impact on engine performance. Without variable valve timing or variable valve lift, the valve timing is the same for all engine speeds and conditions, therefore compromises are necessary to achieve the desired result in intake and exhaust efficiency . This has been described ...
Nissan Variable Valve Event and Lift (commonly abbreviated as VVEL) is an automobile variable valve timing technology developed by Nissan.. Nissan VK50VE Engine. Nissan VVEL was first introduced to the US market in late-2007 on the 2008 Infiniti G37 Coupe sporting the new "VVEL" VQ37VHR engine (VQ37VHR motor specs: 11.0:1 CR, 95.5mm bore, 86mm stroke, 7500rpm redline).
The Valvetronic system is a BMW variable valve lift system [1] which, in combination with VANOS, allows infinite adjustment of the intake valve timing and lift. [2] [3] The system claims to improve fuel economy and emissions, and negates the need for a throttle body in regular use. [4]
VVTL-i (Variable Valve Timing and Lift intelligent system) (also sometimes denoted as VVT-iL or Variable Valve Timing and Intelligence with Lift) is an enhanced version of VVT-i that can alter valve lift (and duration) as well as valve timing. It was introduced with the 16-valve 2ZZ-GE engine found in the 1999 Toyota Celica.
For variable valve lift, competing technologies (e.g., Honda's VTEC and BMW's Valvetronic) use electromechanical concepts, achieving valve lift variation via dedicated mechanisms; it can also be combined with camshaft phasers to allow control of both valve lift and phase. In contrast, MultiAir uses managed hydraulic fluid to provide variable ...
Porsche's more recent VarioCam Plus combines variable valve timing with two-stage lift on the intake side. The two-stage valve-lift function is performed by electro-hydraulically operated switchable tappets. Each of these 12 tappets consists of concentric lifters which can be locked together by means of a pin.
The inlet camshaft position is advanced 25 degrees, thus increasing valve overlap. It remains in this advanced state until about 5000 rpm when the solenoid switches off, and the variator piston returns the valve timing to its natural state. The variable timing increases the engine's mid-range flexibility and reduces emissions.