PD vs common rail

I want to read on the difference between the common rail and PD pump. I want to refresh my memory how both pump works exactly. I did a search, but not much came up with real technical info. I remember Skypup did explain it, but can't find that post at all.

Is there a web site that explains the way both pumps works??

The FAQ doesn't say much either.

Thanks

I can give you a very basic description.

Common rail fuel delivery utilizes a pressurized "rail" in which all of the fuel travels. Injectors then tap directly into that rail. Pumpe-Düse uses what is called unit injection, that is the injectors each have intergrated fuel pumps, the injector and fuel pressurazation are combined in one unit. I think Ford's (Internation) PowerStroke engine uses similar technology if I am not mistaken.

VAG cars are the only passenger vehicles that I know of that use direct injection diesels with unit injection. Peugeot, Renault, Fiat, Mercedes and every other manufactuer of diesel cars use either common rail or rotary injection pumps like we have in our TDI here in the Americas as far as I know.

I am kind of in the dark on this too. What exactly is the TDI? Is it common rail direct injection? That is what I thought it was. Am I wrong?

AFAIK, all North American TDIs are rotary injection pump (like older diesels) but direct injection (unlike older diesels). Common rail is used by Mercedes on their CDI engines.