Manufacturers like to use the lot of acronyms on their cars. Variable valve lift ...
Manufacturers like to use the lot of acronyms on their cars. Variable valve lift (VVL) and the variable valve timing (VVT) are two of the most popular ones.
These systems sound pretty similar, and what do they actually do? Luckily, there’s the real engineer here to explain it to us.
Variable valve lift is mainly used to enhance performance. Well, instead of having one cam profile for the entire rev range, the VVL engine has two: low-lift and high-lift.
Under regular conditions, the engine will use a low-lift cam to operate the valves, but under higher load, the solenoid switches the engine over to the to the high-lift cam (or cams), increasing valve travel and therefore, performance.
Variable valve timing, on other hand, is used mainly for emissions control. Essentially, it allows the engine to advance or retard a valve timing using oil pressure.
This allows for more control over how much air-fuel mixture is in a cylinder (less under light-load driving, more when the power is needed), controlling temperature and emissions.
But that’s only the very basic explanation. Watch as Jason Fenske of Engineering Explained walks us through VVL and VVT in much more interesting detail.
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