Vacum Brake Booster

Uses the differential of engine vacuum (negative pressure) and atmospheric pressure (positive pressure) to multiply force from the driver’s leg. This applies increased force to the pushrod of the master cylinder, generating more pressure from the master cylinder than from use of the driver’s leg alone.

Valvetronic

Varies the power output via the quantity of air fed into the cylinders, making for particularly efficient combustion and optimum utilisation of power. It is complemented by the fully-variable intake manifold plus the double-Vanos variable camshaft system, which allows large amounts of torque to be delivered even at low revs.

VANOS

VAriable NOckenwellen Steuerung (German) - A combined hydraulic and mechanical camshaft control device managed by the car's DME engine management system. The VANOS system is based on a discrete adjustment mechanism that can modify the position of the intake camshaft versus the crankshaft.

Variable Back Pressure Exhaust

More supercars now employ variable back-pressure exhaust. It is somewhat like the variable intake manifold, which is located at the exhaust. Normal exhaust pipes for sports cars collect exhaust pulse from individual cylinders and combine them to a larger pulse, with a corresponding lower pressure behind the pulse. This low pressure actually helps drawing more air / fuel mixture into the cylinder from intake manifolds. This is so-called "reverse supercharging".

Variable Intake Manifold

Increasingly more popular since the mid-90s. It is employed to boost low to medium speed torque without any drawback in fuel consumption or high speed power, thus improve flexibility of the engine. An ordinary fixed intake manifold has its geometry optimized for high speed power, or low speed torque, or a compromise between them. Variable intake manifolds introduce one or two more stages to deal with different engine speeds. The result sounds like variable valve timing, but variable intake manifold benefits more low-speed torque than high-end power. Therefore it is very useful for sedans, which are heavier and heavier these days. For better derivability, there are also increasingly more sports cars feature variable intake manifold alongside VVT, these including Ferrari 360 M and 550M.

VDIM

Vehicle Dynamics Integrated Management - Acquires data from a host of sensors strategically placed throughout the car. Information picked up includes wheel rotation, brake pressure and movement of the car's body. Thus informed, VDIM will apply various stability and safety systems - such as Anti-Lock brakes (ABS), Electronic Brakeforce Distribution (EBD), Traction Control (TRC), Vehicle Stability Control (VSC) and Electric Power Steering (EPS) - to varying degrees. This achieves an optimum that could not be found if each application worked independently.

Vehicle Dynamics - Behaviors

Friction circle: This is basically a vehicles performance envelope. It's expressed in lateral G’s, accelerating and braking G’s. When graphed, the friction circle looks like an egg with the X axis lateral G’s and the Y access braking and accelerating G’s.

VGRS

Variable Gear Ratio Steering - When driving at speed in a straight line, we don't want the car to change direction with every tiny movement of the steering wheel. Around town and when parking, we demand the opposite - quick changes of direction from small steering inputs.

VIN

Vehicle Identification Number(s) are standardized. They all contain 17 characters. VIN characters may be capital letters A through Z and numbers 1 through 0; however, the letters I, O and Q are never used in order to avoid mistakes of misreading. No signs or spaces are allowed in the VIN.

VLIM

Variable Length Intake Manifold - As the name implies, VLIM can vary the length of the intake tract in order to optimize power and torque, as well as provide better fuel efficiency. There are two main effects of variable intake geometry:

Voice Control System

Activated by pressing a key on the multifunction steering wheel, and provides a safer, more convenient way of controlling a vehicles cabin features. The system recognizes up to 500 preset terms (varies from model to model), depending on the features with which the vehicle is equipped. The simple verbal commands are picked up by a special hands-free microphone that filters out background noise.

Voltage Regulator

The voltage regulator controls the field current applied to the Alternator. When there is no current applied to the field, there is no voltage produced from the alternator. When voltage drops below 13.5 the regulator will apply current to the field and the alternator will start charging. When the voltage exceeds 14.5 the regulator will stop supplying voltage to the field and the alternator will stop charging. This is how voltage output from the alternator is regulated. Amperage or current is regulated by the state of charge of the battery. When the battery is weak, the electromotive force (voltage) is not strong enough to hold back the current from the alternator trying to recharge the battery.

Volumetric Efficiency

The variation in torque with RPM is strongly influenced by the volumetric efficiency, or “breathing efficiency.” Volumetric efficiency actually describes how well the engine functions as an air pump, drawing air and fuel into the various cylinders. It depends on various engine design parameters such as piston size, piston stroke, and number of cylinders.

VRIS

Variable Resonance Induction System - Another variant of "Variable Length Intake Manifold"

VSA

Vehicle Stability Assist - Honda’s version of vehicle stability technology. See also VSC

VSC

Vehicle Stability Control - Even the best drivers can get caught out by a bend that tightens unexpectedly - or the need to brake suddenly in mid-corner. Either action can unsettle the balance of the car. That's when VSC steps in to help the driver regain control quickly. Sensors continuously monitor and cross-reference speed, steering angle, yaw rate and deceleration. The instant the system detects a loss of control, VSC steps in and momentarily dictates the individual braking force sent to each wheel. It also moderates the throttle until the tendency of the front to run wide (understeer), or the rear to break away (oversteer), is corrected.

VTG

Variable Turbine Geometry - Turbochargers with variable turbine geometry, change the output of the turbine as a function of engine load. In this way the optimum boost pressure can be maintained and optimum use can be made of the energy in the exhaust gas. Cross-sectional changes are made by resetting the turbine blades (smaller contact surface at low speeds, larger contact surface at high speeds).

VVEL

Variable Valve Event and Lift (Nissan's newly (2007) developed) - While conventional engines control air intake using a throttle valve, VVEL-equipped engines do this directly at the intake valves, continuously controlling their valve events and lifts. 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. The new engine offers the following advantages depending on driving range:

VVL

Variable Valve Lift + Timing is an automobile variable valve timing technology developed by Nissan. VVL varies the timing, duration, and lift of valves by using hydraulic pressure switch between two different sets of camshaft lobes. It functions similarly to Honda's VTEC system.

VVT

Variable Valve Timing: After multi-valve technology became standard in engine design, Variable Valve Timing becomes the next step to enhance engine output, no matter power or torque.