While the rest of the world moved on to Common Rail engines, the VAG (Volkswagen Auto Group) preferred instead to develop on their very successful TDi Direct Injection diesels.
Thus PD or Pump Duese (spelling may be incorrect, I dont speak German) was born - it was an improvement on the Direct Injection diesels (that you see in the original Skodas, for example) it featured individual injectors AND miniature individual fuel pumps PER CYLINDER.
PD is therefore considered a derivative of the TDi or Turbo Direct Injection engines that VW produced - it isnt common rail technology.
Common Rail diesels, on the other hand, relied on a high pressure common rail to provide the fuel delivery.
PD is also more expensive to produce because it features one pump per cylinder. And as it turns out, these engines are also noisier (ask Fabia owners!) than Common Rail engines and havent managed to pull out as many horses from the engine as common rail engines. For example, the 2 litre PD engine found in our Lauras and Superbs also features in a higher state of tune on the Passats and Audis. Consider this:
- The 2.0 PD from VW produces 140 bhp of peak output and 32.5 kgm of torque in its highest state of tune.
- The new 'R' series 2.0 CRDi from Hyundai, on the other hand, produces 185bhp and 392nm of raw torque.
This is why VW have finally decided to join the Common Rail club, moving away from their PD engines to Common Rail engines in all their diesel cars. Hopefully this will be the end of the not-so-successful PD experiment.
 Keep those wheels turning!
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