"Adrian" <toomany2cvs@gmail.com> wrote in message
news:Xns967B67066745Eadrianachapmanfreeis@204.153.244.170...
> Ian Rawlings (news05@tarcus.org.uk) gurgled happily, sounding much like
> they were saying :
>
>>> due to the TD5 being direct-injection rather than common-rail which
>>> basically means every injector is its own injector pump.
>
>> Hmm are you sure about that? I think you're confusing two different
>> buzzwords, direct injection and common rail deal with different parts
>> of the fuelling system as I understand it.
>
> He's also confusing common-rail with VW's pumpe-duse.
>
> Direct Injection injects directly into the combustion chamber not into a
> pre-chamber or manifold.
>
> Common Rail uses fuel at very (25,000psi+) very very high pressure in the
> fuel rail fed by a second pump, the main one being used to get the fuel
> from tank to rail pump.
>
> PD uses fuel pressurised to that very high pressure at the injector by one
> combined pump/injector per cylinder, in addition to the "normal" pump.
I'm a bit late reading this but I have news for both of you. The TD5 is NOT
a common-rail as you know it. It is an unit injector system similar to the
Isuzu Trooper 3.0 unit in some ways. Paul Brown has confused the use of the
term 'direct injection' which means injecting the fuel directly into the
main combustion chamber formed in the piston crown, but otherwise he is
correct in that the TD5 uses unit pump/injectors with a low pressure feed.
This type of fuel system was pioneered by Caterpillar and is used commonly
in heavy trucks and plant.
From
http://www.discoverytd5.co.uk/td5.htm
Central to the Td5 concept was the adoption of EUI technology. This has
already proved very successful over many millions of miles in large diesels,
such as those used in premium trucks, delivering enhanced driveability and
economy as well as providing a high-confidence route to meeting increasingly
tough emissions regulations. EUI uses an individual camshaft-driven plunger
pump for each cylinder's injector, with ultra-precise electronic control of
the injection period and timing.
Huw