Motor Vehicle Terminology Explained in Layman’s Terms Prt Two

                     Motor Vehicle terminology explained in layman’s terms Part two

This is part two of my explanation of Motor vehicle technology terminology.  The motor trade sells to you through these abbreviations so its worth knowing what they actually mean.

VVTI  Means Variable Valve Timing with Fuel Injection. The valve timing on most engines is set as a compromise between economy and performance. Without getting too technical, variable valve timing can produce more power and better economy from your engine.  The amount of time the engine valves are open is dictated by the engine Camshaft which can be adjusted whilst the engine is running in a VVTI equipped car.

The I in VVTI relates to the engine being fuel injected rather than having a Carburettor to deliver fuel to the engine.  Most vehicles produced today have fuel injection so the vehicle can meet fuel emission regulations.  The terminology of Fuel Injection will soon not be used as a selling tool as all vehicles will be equipped with FI as standard.

Picture of a VVTI engine.

SUPERCHARGER.  The Supercharger is very similar to the Turbocharger as described in Part one of this article. This also is another name for a Compressor as advertised on Mercedes vehicles (Kompressor)  All these named devices compress air then force the air under pressure into the cylinders of the engine, which in turn creates a bigger explosion and therefore more power from your engine.

A slight difference between Turbochargers and Superchargers is, the Turbo is driven by exhaust gases, where as the Supercharger/compressor is driven by a belt or gears which by design takes some power from the engine.  A turbo is known as non-parasitic as in it takes no power from the engine to create more power.

A Supercharger.

TIPTRONIC or SEMI-AUTO GEARBOX.  This type of gearbox is a cross between a manual gearbox and an Automatic gearbox.  The driver can change gear by use of paddles around the steering column very much like a racing car.  One paddle changes the gears upwards I.e. 1st 2nd 3rd and the opposite paddle changes down gears.  The gearbox can also be selected into full auto mode where by the driver need not change gear himself.

This type of transmission is a compromise as in it isn’t as smooth as a fully automatic gearbox and it isn’t quite as strong as a full manual gearbox.  The technology is getting better and the teething troubles are dying away.

A Semi Auto Gearbox.

TRACTION CONTROL.  This is a way of preventing the driving wheels on a vehicle from spinning under harsh acceleration.  When tyres are spinning and burning rubber it may look spectacular but the vehicle isn’t under control and its acceleration is much slower than a wheel with full traction.

This system works like a reverse ABS system a control unit senses when a wheel is spinning due to severe power from the engine.  The control unit will limit fuel to some or all the engine cylinders until the wheels stop spinning and becomes under control.  Many drivers like to wheel spin their vehicles so manufacturers normally fit an override switch enabling the Traction control to be switched off.

EFI.   Stands for Electronic Fuel Injection. There are two types of Fuel Injection one is Mechanical Injection and the other is Electronic fuel Injection.  The EFI system has pretty much taken over from the mechanical system once again due to stringent emission controls. However manufacturers still use EFI as a selling point for their vehicles.

An EFI Manifold and Fuel Injectors.

The mechanical system was used on early Porsche’s and VW’s and it dates back to WWII as was used by Germany in their ME109E fighter aircraft.

If you are contemplating buying a new vehicle and are unsure of what all the letters after a vehicles name mean just ask?  You have a 50/50 chance the salesman may know the answer.  Part three to follow shortly.

Lord Banks