Fuel injector pintle caps

[twoqu]

I have the pleasure of replacing a cracked pintle cap on an RS2 injector. Have searched and there appears to be quite a few variants. Its difficult to get an accurate measurement from a cracked one but as far as I can tell it has the following dims:
2.0mm ID nozzle exit straight.
7.5mm ID cap at the top, 7.80mm at the bottom. There is a ridge inside.
It's brown in colour!
The ABY/AAN one is quite different. For a start its green and it has a trumpet exit, flaring from @2mm to @3.5mm. Not sure of the ID as I don't want to break that as well!
No doubt Bosch colour coded the various pintle caps to aid identification although I am a bit surprised that the RS2 cap is not identical to the ABY one which presumably is a trumpet shape to allow a different spray pattern from the multihole discharge rather than a pencil flow from a single discharge.
I will have to find a 3B injector but I seem to remember that also having a brown pintle cap.
So can anybody confirm those dimensions and have a UK source of the correct pintle caps.

[twoqu]

The other important dimension is of course the height of the cap which is @6.75mm!
I spotted a similiar looking brown cap on a side feed injector from a T4 but it was not till I had levered it off that I realised it was half the height! It did however have identical dimensions otherwise. Just goes to shop what a potential minefield it is.

[twoqu]

Where is the tumbleweed icon?
Found the injectors under a pile of other stuff and realised I had not solved this perplexing question!
Unfortunately the pic is not the greatest but it should illustrate the differences in the two types of pintle cap. The brown being the ADU and the green AAN/ABY. You should be able to see that the ADU one is a straight hole and the AAN/ABY one is flared. I thought that they might have used the 3B pintle cap on the ADU but that looks different again. I measured the ADU one at 1.92mm and there does seem to be a pintle cap that size. The base of the brown cap is @1mm wider in diameter for some reason.
With a magnifying glass I could see that the top of the ADU injector where the orrifice holes are had 814 on it whilst the AAN/ABY one had 781. Perhaps thats the size of the orrifice. There were some other numbers on the injector body which are normally obscured by the plastic spacer and O ring. On the ADU were 8294 and 060 4078 and then a space and either 5 or S. On the AAN/ABY they were 2782 and then 060 2837. If that extra letter/numeral was an S, I wonder if they implies that the original origin of the RS2 injector was the fabled 968 Turbo S which I believe was 2V thereby explaining the narrow stream pintle as opposed to the the flared pintle for a 4V. As the AAN/ABY was already using that injector prior to the development of the ADU you would have expected it to have used that style of pintle cap as the induction was not significantly changed. Or Porsche just chucked in whatever they had kicking about that done the job!

[bluequattro]

I need to sort one of my rs injectors the same when I get round to it
I'll save this post!

[twoqu]

It does seem counter intutitive. You would think that the flare on the AAN/ABY cap would allow for the spray to be divided into 2X2 streams, one for each port whereas the straight one would produce 4 straight streams aimed at the central divider. Can't really see the logic of it to be honest. Perhaps its not as different as you would expect.
Not sure what would happen if the straight one was replaced with the flared one!

[UrS4boy]

Just pulled my RS2 injectors this afternoon to do the injector inserts. Green top, black body and, yes, brown pintle cap. Hmmm...

[twoqu]

Would be interesting to see what if any difference these pintle caps have. If the spray of both injectors is the same then perhaps there is nothing in it. Not even sure whether the flow is just 4 straight streams in both either. If there was any angle on the flow then the straight ADU one would act like a pipe whereas the AAN/ABY one would allow some divergence.

[mcandmar]

There is one way to test the spray pattern, not that i would advocate doing something so irresponsible

[UrS4boy]

Just pulled my RS2 injectors this afternoon to do the injector inserts. Green top, black body and, yes, brown pintle cap. Hmmm...

Just got my RS2 injectors back from Precision Injector (they have an ANSU machine to test the injectors). I had them cleaned and refurbed.

Before:

1 Spray Pattern Good 432 cc/min at 4 Bar
2 Spray Pattern Fair 420 cc/min at 4 Bar
3 Spray Pattern Good 436 cc/min at 4 Bar
4 Spray Pattern Fair 432 cc/min at 4 Bar
5 Spray Pattern Fair 420 cc/min at 4 Bar

After cleaning and refurbing:

1 Spray Pattern Good 440 cc/min at 4 Bar
2 Spray Pattern Good 440 cc/min at 4 Bar
3 Spray Pattern Good 440 cc/min at 4 Bar
4 Spray Pattern Good 440 cc/min at 4 Bar
5 Spray Pattern Good 440 cc/min at 4 Bar

This is the after appearance (the O-ring on top is brown now (!?)) The old tip was brown, the new one is green.



The new green cap tip, seems quite straight, not much flare at all. (??)

[twoqu]

Apart from the colour it does look like the pintle caps have the same design as the original brown ones but not the AAN/ABY ones. Quite like the matching collar and cuffs look.
Dave can you get a p/n or cross reference for those? At a guess the original colour of the pintle caps was probably indicative of something, at least to Bosch! Perhaps it has little or no effect on the injector stream but why then all the different ones?
Would be quite happy to source some replacements. Once split (through damage or intentionally) they are easy to remove. Replacement can be performed by using a small socket to hold the cap whilst pressing down on the injector. So that well within the scope of anyone who can wield a Stanley knife. You would be unluck if a cracked cap somhow made its way into the engine but why take the risk for a few £ ($)!

[Avantus]

anyone that knows where to get a correct RS2 one?

I've got one cracked pintle cap, and finding the correct one seems a nightmare!