Getting air in and exhaust gases out of the combustion chamber under all speeds and driving conditions is essential for a car’s fuel efficiency and low emissions. That’s why virtually all Chevrolet ...

GM has announced that all V-8 powered Chevrolet and GMC trucks now feature variable valve timing (VVT) for the 2010 model year. A quick trip back to engineering 101 reminds us that VVT is a piston ...

The VVT system operates by advancing and retarding the cam timing to suit the speed and load of the engine. Generally speaking, advancing the cam (from 0) tends to improve low-speed power, while ...

But because today's near-ubiquitous OHCs, driving valves from above, enjoy inherent efficiency advantages over one in the block operating them from below through pushrods while enabling higher rpm for ...

It's springtime! Time to start working on your project car, learn a new wrenching skill, discover what everything is under the hood (and how it works), or just spruce up your daily driver. All month, ...

The tough guy in you says to stab that cam in retarded a few degrees for maximum top-end horsepower, while your more practical alter ego suggests advancing it a hair for improved low-end torque and ...

General Motors’ all-new 3.9L V6 has been honored with a Breakthrough Technology award by Popular Mechanics for its innovative use of variable valve timing in an overhead valve engine. For ages GM has ...

Variable valve timing (VVT) and variable valve lift (VVL) have very similar names, both referring to variable valve performance. Does that mean that they are basically the same thing? The are most ...

When it comes to the many variables of combustion inside an engine, engineers measure the timing of key events in degrees of crankshaft rotation, a relative frame of reference that remains constant ...

A variety of two-stage, or discrete, variable valve lift (DVVL) and continuously variable valve lift (CVVL) systems have recently been incorporated in production vehicles. Several systems that have ...