Glossary
Valves
VALVES
A valve is a device that regulates the flow of gases in and out of the cylinders of an internal combustion engine. Intake valves allow the air and fuel to enter the combustion chamber, while exhaust valves allow the burned gases to exit after combustion.
Viscous Coupling
VCU
Viscous Coupling (VCU) can act either as limited slip differential (LSD) or as a central differential in some all-wheel drive vehicles. The device itself consists of two sets of alternating and perforated metal plates mounted in a sealed drum, which are engulfed into a silicone or similar liquid.

Each set of plates is connected to a propshaft, and can transmit or limit the power between the two shafts depending on the speed of the plates, which heat up the aforementioned liquid, thus modifying its viscosity. In turn, more or less torque can be transmitted between two axles or two wheels according to the individual speed of the axles (or wheels.)
Vehicle Dynamic Control
VDC
Vehicle Dynamic Control (VDC) is Alfa Romeo's marketing name for the Electronic Stability Programme, and is used to counter understeering and oversteering, thus improving vehicle stability during high-speed turns or on low grip surfaces.
Variable Nozzle Turbine
VNT
Variable Nozzle Turbines (VNTs) have electrically adjustable guide vanes which can modify the boost pressure according to different engine speeds, thus counteracting the turbo-lag experienced by most turbocharged engines while increasing their power output and maximizing fuel economy.
Vortec
VORTEC
Vortec is General Motors' marketing name for a group of engines which are particularly used in most of their trucks and truck based SUVs.
Vehicle Stability Assist
VSA
Vehicle Stability Assist (VSA) is Honda's trademarked name for a version of the Electronic Stability Programme, which can assist vehicles from skidding (understeer and oversteer) and mantain control by individually braking each wheel and even reducing engine power to provide stability.
Vehicle Skid Control
VSC
Vehicle Skid Control (VSC) is Toyota's trademarked name for a version of the Electronic Stability Programme, which can assist vehicles from skidding (understeer and oversteer) and mantain control by individually braking each wheel and even reducing engine power to provide stability. Like all other similar systems, it uses the ABS sensors and a yaw sensor to detect if the vehicle is out of control and acts accordingly.