Loading ...
TDI technology explained
In a previous post, I raised the subject of how a diesel engine basically works, considering just the basic principles. Today, I would like to show you the specifics inherent to TDI technology, with a focus on the latest generation of these engines. You could learn some interesting things.
TDI for dummies
For those whose technical knowledge of cars is limited (hello Normand!), TDI technology can be summarized as such: they are diesel engines on which a turbo-compressor has been transplanted and whose fuel injection system works on the principle of direct injection into the cylinders. The turbo-compressor significantly increases the torque produced without threatening the longevity of an engine, because diesels are built naturally sturdy. The direct injection reduces noise and the amount pollutants in addition to increasing efficiency and driving pleasure.
It’s as simple as that. For the long version, read on.
First generation TDI
First of all, note that Volkswagen is in its third generation of TDI engines since 1993. The first TDI generated 90 hp and used direct injection technology via a distributor pump. The injectors were able to produce two injections of fuel per cycle, and it used a variable-geometry turbo-compressor, like those of subsequent generations. The fuel injection pressure was in the vicinity of 220 bars. The antipollution system used an exhaust gas recirculation device and a catalytic convertor. At the time, these first TDIs already offered more power and torque than traditional indirect injection engines, and the two injections per cycle reduced the noise produced and minimised polluting emissions.
Second generation TDI
The second generation engines, available from 2004 to 2007, used Pumpe Duse unit injector technology and generated 100 hp. A more powerful version (136 hp) of this engine was also available for the Passat. Here, the injectors could produce an injection pressure of 1920 bars, producing power and torque while still reducing pollutants even more. In addition, these electronically commanded injectors were more precise than those of the preceding generation, which favoured better combustion and a reduction in noise. The exhaust gas recirculation was now water cooled for greater efficiency and reliability.
Third generation TDI
The latest evolution of TDI technology relies on a common rail direct injection system. Here, the fuel pressures are variable and can reach 1800 bars. The piezoelectric injectors are ultra-rapid and allow multiple injections, up to 5 injections per cycle. This mode of multiple-jet injection reduces noise and exhaust smoke and ensures more complete combustion and the regeneration of pollutants.
The common rail TDI also uses pressure sensors in each cylinder. They are combined with glow plugs, and these sensors enable a calculator to refine the injection parameters depending on the quality of the fuel and the wear of the engine. This permits a cleaner operation over the lifespan of the engine. Other systems have also been redone, like the ultra-efficient glow plugs which make starting as quick as gasoline engines, in temperatures as cold as -24 C.
Finally, the antipollution system of this latest version uses three catalytic convertors and a particulate filter, making the TDI 2009 the cleanest diesel engine of its generation.
If you have any questions on the new TDI engine, let’s talk!
0 Comments