All anniversarry golf TDi's are 150bhp and PD = Pumpe Duse and translates as 'unit injector' - a device that supplants the old distribution pump as the source of back-pressure at the injector nozzle. In effect, PD injectors each have their own little cam-operated pump to produce even higher pressure (30,000 psi) than a common rail system, which uses a thin, tubular reservoir to contain pressurised fuel for feeding on demand to each of the injectors in turn.
The higher the pressure, the more effective and leaner becomes the upper-cylinder burn. Consequently unit injectors (PD) produce more power and torque for a given measure of fuel without cost to fuel consumption and CO2 emissions. As an example, the 130 bhp TDi PD engine in the test car, for the same 1.9 litres as the TDi unit it replaces, generates 13 per cent more power (130 bhp) and nine percent more torque yet returns an identical 52.3 mpg on the combined cycle.
So there
