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Some Website said:Non-PD Vs PD
In a gasoline engine, a mixture of fuel and air is compressed and then ignited with an electrical spark. A diesel engine relies purely on compression to ignite the mixture. When air is compressed it heats up - ever notice how hot the pump and hose get when hand-pumping a bicycle tire or ball? The amount of compression required for ignition in a diesel engine is far greater than that used in a spark ignition engine. So upon ignition, a significantly greater force is applied to the crankshaft resulting in greater torque.
The previous 1.9 litre turbo diesel engine - in fact, in most modern diesels - used a system where the fuel air mixture was introduced via a common rail. These systems generate a swirling motion of the air around the intake valves through especially designed intake ports. This motion causes faster mixture with the fuel when it is introduced and thus more complete combustion. This, in turn leaves less unburned fuel and emissions.
Pumpe Duse is a new fuel management and delivery system that places a pump injector at each individual cylinder producing a finer spray for better and more efficient combustion. Instead of a pre-combustion chamber found in most diesels, fuel is injected directly into each individual combustion chamber under terrific pressure at precisely the right moment. The PD works like an overhead cam system, using cam lobes to determine the timing and amount of the spray into each cylinder. The new system reduces heat loss, results in a quieter, cleaner engine, faster cold weather starts and improved low-end torque.
slimjim said:I just found this little nugget. You guys have explained this to me ... But I thought this may help more newbies....
Only the fuel is introduced via the common rail ? Air comes via normal inlet valves.in most modern diesels - used a system where the fuel air mixture was introduced via a common rail.
Most car diesel engines abandoned the pre-combustion chamber ages ago, and have been direct-injection for quite some time, the quoted statement applies equally to common-rail engines and pre-PD TDIs, as well as PDs. The main difference is that the PD system achieves a much higher injection pressure than common rail.Instead of a pre-combustion chamber found in most diesels, fuel is injected directly into each individual combustion chamber under terrific pressure at precisely the right moment.
If my understanding is correct, the cam lobes do drive the pumps to build up pressure, but there's also electronic control of each injector too. The wires to each injector run internally through the cylinder head, laying in the oil. See this rather techy post for more in depth details of the PD pumps/injectors.The PD works like an overhead cam system, using cam lobes to determine the timing and amount of the spray into each cylinder.