Plunger/Injectors

[xud9te]

Hi,

Is there any benefit in increasing plunger size without an increase in injector nozzle size on the IDI engine?  

I would have guessed that there would be an increase up to a point before the restriction to flow at the injector was equal to the availiable fuel pressure at the injector, but that before this happened the injector would open faster, spray more fuel in a shorter time and atomise better?

However, if there is any fuel left over being supplied later, i.e. at the end of the stroke due to the injector being too small to supply the whole amount of fuel metered by the larger plunger in the correct time window, this will result in smoke, right?

I guess the question I am asking is how much is this a consideration?  The amount of restriction (or maximum flow) will all depend on the geometry of the nozzle itself, which I cant seem to find much dimensional info about.

I have bosch 219 (IDI) injectors at the moment and am moving to an 11mm plunger size from 9mm.  The injectors that came with the larger plunger engine are no good as they are from an older style 2L DI engine with VE pump.  What IDI injectors are a good upgrade from this size?  I am having some trouble finding cheap (i.e. scrapyard sourced! :roll: )  bigger injectors.  I dont suppose there is a datasheet with injectors vs application anyone can point me to?

Also, i have a plunger from a Right turn engine VE Pump to fit in a Left turn engine VE Pump, but assumed as the plunger itself was symmetrical that there should be no problem, is there anything else i need to consider? Springs?

Many questions but this has got to be the best place to ask!!

Cheers

[xud9te]

Thanks for the reply andrew,

Ill race you then see who gets it done first!!!  What injectors are you going to use?  What size is the plunger?

Greg

[xud9te]

Hi again,

Looks like I have the correct rotation pump after all, so no need for me to worry.

Back to the injectors, i am going to change the nozzles on a couple of test sets of injectors and see how we go.

The nozzles I have availiable to try are:

DNOSD289/ 0434250166  (Citroen 2.1 td)
DNOSD265/ 0434250128  (MB 300 etc)
DNOSD294/ 0434250155  (LT van, other VW's)

Ones I am not sure of are;

DNOSD293/ 0434250103
DNOSD306/ 0434250167

Any ideas waht these last two are?  Maybe tin-tin can tell us?

I am sure that the MB injectors are supposed to use a pre-injection stage so not sure if they will work without the double springs too well, have you looked into this Andrew?



Cheers
Greg