Fitting modern common rail diesel injection to a tdi engine

[dubwarrior2]

Soooo....this weeks musings.

I'm building a Vw t4 with a 2.5tdi engine.
These are good strong engines with decent bosch injectors and fuel pumps.
A lot of people seem to struggle with these engines as they cant seem to set the fuel pump timing correctly.

I was wondering if anybody had managed to get rid of this semi-mechanical injection system and retro-fit a common rail diesel injection system.

I'm sure it would be much more tunable.
You would of course need to change the injectors, fuel rail, pump, wiring and ECU but I don't forsee any major issues. Especially as the petrol boys have been doing if for so long.

[vitesseefi]

Why would you do that? The original system is pretty effective, reliable and tunable. The Audi AEL version is 140 bhp standard and chips to 170ish without mechanical mods.

Also used in the Volvo 850/V70 TDI (D5252T). With nozzle changes and bigger turbo they can make 240 bhp plus with huge torque. There is LOADS of info out there on tuning these with the original injection equipment.

There is a descendant of this engine used in later transporters that has common rail (factory versions up to 190 bhp IIRC) but don't know whether this is closely enough related to be interchangeable wholly or in part.

Nick

[dodgerover]

What he said ^^^ why would you? There's plenty of people who have reverted diesels back to fully mechanical injection to get away from that sort of thing....

[waveman1500]

The shape of the combustion chamber and piston tops is very important in optimising diesel injection, so it would be better to swap in a whole engine as an integrated system. For the cost of doing the injection swap, I would guess that buying the whole engine would be cheaper anyway.

[welshpug]

IF there's a commonrail variant of the same engine then yes it's possible, financially viable? not likely.

there are engines out there with roto pumped and commonrail variants, fords endura and puma engines.

I know the injectors in the tdi engines look much like commonrail units, just without the solenoid head.

[dubwarrior2]

Its all just hyperthetical guys.
Just wondering if it was possible and if it would be any more advantagous.

[welshpug]

you'd have a finer degree of control over fuelling and boost, emissions etc.

however as you already have an ecu controlling a VP pump and a solenoid controlled turbocharger (possibly even a vnt) theres loads of tuning potential out there already in the form of upgraded injectors larger intercoolers and custom ecu maps you're already well catered for.

yes getting the timing right can be quite a faff, but its not impossible and just takes time to get it right.

try it in an LT where the pump is right at the back by the bulkhead...

[vitesseefi]

The timing is very easy provided you have the necessary software (Vagcom/vcds - freeware version does NOT include the timing utility), but impossible to do properly without.

Nick