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    Thread: VR6-AFP Intake/Injector Question

    1. 03-02-2020 06:36 PM #1
      Hey;

      This will hopefully be easy for one of you Techy VR Geeks to answer.

      Stock 02 AFP intake and injectors. The injectors have two seals, and a "screened and vented" section between the o-rings where they plug into the manifold. The manifold has a hole at 6 o'clock that connects to a chamber that connects all 6 similar injector ports together. On the front of the manifold, there is a plastic 3/16" or so hose barb that connects this chamber to.... something, in the stock configuration.

      The application for this engine is a few million light years away from stock, but I have an interest in employing these injectors because of their compact size. Can anyone tell me what this vent/feed system in the intake may be for? Venting fuel vapors out, or back into the intake?

      Thanks in advance!

      - Redlineman

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    3. 03-02-2020 08:54 PM #2


      The hose barb that draws from this passage can be seen here on the lower left, which would be on the passenger side front of the engine, as transversely mounted.

      EDIT - The manifold in this pic is upside down. That would put it on the driver's side front.
      Last edited by Redlineman; 03-03-2020 at 08:47 AM.

    4. 03-02-2020 09:11 PM #3


      I found this pic of the hose that connects to that intake port, but I still do not know what it connects to. I erred in my previous statement that this was on the passenger side. It would be on the driver's side front.

      If you were curious, I have 4 of these engines, but none of the cars they came from.
      Last edited by Redlineman; 03-02-2020 at 09:14 PM.

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    6. Geriatric Member need_a_VR6's Avatar
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      03-02-2020 10:28 PM #4
      It is supposed to help atomization. Most high power cars use std injectors without it.
      -Paul
      1992 Corrado - ALL MOTOR Drag Project [email protected] and falling
      KPTuned - Official MegaSquirt: Sales - Repair - Installation - Tuning

    7. 03-03-2020 08:45 AM #5
      Thanks Paul;

      Does it see positive or negative (vacuum) pressure, and where does that hose go? I'd like to find an injector of similar physical size that didn't have that system. I wonder which years used it? Or, I wonder if not providing the port in the bore or any of the hookup would effect the performance of the injector? As usual, more questions than answers!

    8. Geriatric Member need_a_VR6's Avatar
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      03-03-2020 11:43 AM #6
      It is only on the mk4 afp so 99-01 model years. The line goes to manifold vac as far as I know but its worth checking the vac diagram.

      There are some small injectors but most are very high flow 750cc/min up to 2200cc/min I haven't seen ones that size that are smaller. Most are converting to a short runner anyway so its a non issue.
      -Paul
      1992 Corrado - ALL MOTOR Drag Project [email protected] and falling
      KPTuned - Official MegaSquirt: Sales - Repair - Installation - Tuning

    9. 03-03-2020 06:01 PM #7
      Actually, the AFP ran through 02, as that is what all four of mine are, I believe. I did some looking around. The standard 2.8V6 uses what looks to be a physically similar injector, but without that vented area and a single o-ring seal. They would probably be entirely sufficient for my needs. First criteria is compact size, then proper flow numbers.


    10. 03-06-2020 09:36 PM #8
      SRI -



      The front injector is the only one that is space restricted by the hood. I will probably create a remote feed of some sort for it, and run the return line off of a rail that picks up the other 5 injectors. Custom much?
      Last edited by Redlineman; 03-06-2020 at 09:42 PM.

    11. 03-21-2020 05:11 PM #9
      Another question;

      I hope someone is still listening.

      As I mentioned previously, I have a need for an extremely compact (short) injector. I have just returned from my research laboratory - the local Pick-A-Part - where I was investigating the types of injectors used in various VAG engines. I was interested in the 1.8/2.0T and 2.8V6 injectors, as they looked "normal" on the injection end and seemed smaller in profile. The research reveals that they are indeed a normal configuration on the injection end, but they are about a half inch longer than the VR injectors. These original '02 AFP VR injectors are the shortest I have seen, but they have that stupid large diameter vented hood on the end. I will be using an early cast primary intake which has smaller ports for a normal injector. I could bore out the ports in the intake and use the hooded VR injectors, but something tells me I don't want to do that for a style of injector that is uncommon and probably not upgradable in the future if they ever prove too small.

      So, the question is, does anyone have knowledge of injectors, and any thoughts on where I can find very short ones like the hooded AFP injectors, but with a normal pintle end on them? Or, does anyone know of a resource with lots of knowledge about injectors that might be able to size a set of injectors for me?

    12. Geriatric Member need_a_VR6's Avatar
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      03-21-2020 06:10 PM #10
      Dig around usrally team's site. You may find something physically small. It is likely to be higher flow rate than stock.
      -Paul
      1992 Corrado - ALL MOTOR Drag Project [email protected] and falling
      KPTuned - Official MegaSquirt: Sales - Repair - Installation - Tuning

    13. 03-22-2020 10:45 PM #11
      Thanks Paul;

      Those USRT guys look nuts enough to be useful!

      For the record, my research shows the stock AFP VR Weber/Magnetti Morelli injectors - IWP 022 (VW# 021 906 031 D) flow about 20.5lb/hr. The '01 2.8V6 injectors - VW# 078 133 551 BA (Bosch# 0 280 156 273) flow approximately 18 lb/hr. The 1.8T injectors - Bosch# 0 280 156 065 - flow 26.85 lb/hr. I don't find anything overly surprising here, except I'm a little surprised the 2.8 liter injectors are not closer in flow rate.

      What I'm seeing as the biggest problem is the lack of documentation or even interest in injectors that are near the output of the stock ones. By the looks of what is for sale, everybody seems to think they need to drown their fire in gallons of uncombusted fuel. In reality, there is no sense in exceeding by very far the output of the stock injectors without significant mods, and I'm not sure mods like that are really possible in an NA application. In any event, my modest hopes for around 200hp probably require little if anything more than the stock 20-25lb/hr. I'm more interested in the low profile 48mm normal pintle design, or even looking into 38mm squirters to see if there is anything applicable there.

    14. Geriatric Member need_a_VR6's Avatar
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      03-23-2020 11:54 AM #12
      Double the power double the fuel. Now you know why 42lb /hr are popular. With programmable efi you can use nearly any size, I use 160lb/hr in my 3.6.

      You may be best off with the 1.8t injectors. You may be able to also find a 2.5bar fpr which will lower the effective flow rate.
      -Paul
      1992 Corrado - ALL MOTOR Drag Project [email protected] and falling
      KPTuned - Official MegaSquirt: Sales - Repair - Installation - Tuning

    15. 03-25-2020 07:23 PM #13
      38mm Injectors;

      Oddly enough, One of the kings of modern performance - the LS series of Chevy V8s - uses 38mm injectors. Problem is the lowest flow rating is about double the stock VR injectors. Well, not quite (36lb/hr), but I'd rather go smaller and turn up the pressure than go big and loose atomization. Still searching and studying.....waiting folr people to respond to requests for info.....................


    16. Geriatric Member need_a_VR6's Avatar
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      03-25-2020 10:29 PM #14
      Finding anything around 20lb/hr in that small format will be tough
      -Paul
      1992 Corrado - ALL MOTOR Drag Project [email protected] and falling
      KPTuned - Official MegaSquirt: Sales - Repair - Installation - Tuning

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