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Which injectors for big turbo set-up ?

Discussion in 'A3/S3 Forum (8L Chassis)' started by Nyteryda, Nov 28, 2012.

  1. Nyteryda
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    Nyteryda Nyteryda

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    Hello, have recently completed a big turbo build (just finished running in engine on base map) and we are now, before the custom mapping, a little confused as to which injectors would be best for this set-up.. the spec of the build is below...

    GT2871R Turbo
    Hiflow T25 Cast Manifold
    82.5mm Wossner Pistons 8.5:1
    RMR Inlet Manifold
    AGU Head
    ECS Stage 3 Clutch
    Fidanza LW Flywheel
    Uprated Rods
    Simota Induction Kit
    FMIC
    Phenolic IM Spacer
    3" Downpipe
    Full Exhaust
    3bar FPR
    Standard N75 Valve
    N249 Bypass

    Any advice or opinions welcome ...
    #1
  2. Prawn
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    Prawn My other car is a MINI!!!!

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    hmmmmmmmmmmmm, I'd have said 630's for a 2871, you may get away with 550's, but they'd be right on the limit I would have thought.

    One of those two though :p I am making 350bhp on 440's, which many would say isn't possible, so perhaps the 550's would do. 630's would have more headroom though
    Last edited: Nov 28, 2012
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  3. superkarl
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    superkarl MAN OF STEEL

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    and let us know what it makes! im intrigued
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  4. Prawn
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    Prawn My other car is a MINI!!!!

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    shame about the low CR ;)
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  5. Andrew@A.L.D
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    Andrew@A.L.D Cylinder Head Master

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    630cc i would say? I take it your planning for 350/380bhp?

    Welly had them in his car and that was at 450 bhp so they do well

    Not sure how well 550cc would cope?
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  6. Nyteryda
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    Nyteryda Nyteryda

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    hi prawn, thanks for the advice.. so would you say your 440s are at their max at 350bhp ?

    In all honesty I have had the custom mapping done already, i just thought it would be easier to step back in time to before the custom mapping was done to get some opinions/advice on the best way forward rather than this being a 'slag-off-a-tuner' thread.

    On the day of the map, 450cc Green Giants were sold to me by the tuner as the correct choice for my set-up and the custom map came in at 341bhp which I was pretty disappointed with tbh.. From 6krpm it seriously leans out which is very unnerving and I now also have rough starting, jerky 1st gear, rev-hang & exhaust pops/bangs between gear changes and a slight fuel smell in the vehicle at times (none of which were present during the running in stage)
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  7. Prawn
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    Prawn My other car is a MINI!!!!

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    sounds very odd to me mate, I am running 353bhp from bosch 440's at 3 bar, and it very happily runs mid 11's AFR to 7400rpm with no leaning out at all, on a stock LCR fuel pump too.

    341bhp also sounds pretty low given the spec!

    I assume all this is in an S3?
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  8. Nyteryda
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    Nyteryda Nyteryda

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    hi Andrew, yes was hoping to get nearer the 380 mark, that was the target from the start of the build. After all the labour expense, high quality parts and time invested in the car I feel a bit let down by the tuner. They actually said before the custom map that I had standard injectors and needed to upgrade, I trusted their word and recommendation on the day (i'm no expert) and went with the 450s. When I eventually managed to get the old injectors back off them i looked up the part number and they were bosch ev4 470ccs which has confused me even more, why put in smaller ones ??
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  9. Nyteryda
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    Nyteryda Nyteryda

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    Hi Prawn, yes its in a 2001 S3.. The a/r goes as high as 17 (!) towards the red-line (from around 6krpms)
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  10. Prawn
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    Prawn My other car is a MINI!!!!

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    standard injectors are 380's mate, so god knows what yours were.
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  11. Prawn
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    Prawn My other car is a MINI!!!!

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    I'd be taking my foot off pretty bloody quickly if I were you! that's not safe to drive at all.
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  12. badger5
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    badger5 RIP S3dave Site Sponsor

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    440's too small, 550's a little on the edge on 3bar fpr, 620's would be my choice.. remap change required to rescale them when you change.
    I hope you're not revving it to get that lean... it wont end well as you know.

    what spec a/r turbo? what boost has it been "mapped" to run? got any datalogs and dyno plots to look see?

    sounds a little like some "pup" advise has been given along the way sadly.
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  13. Nyteryda
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    Nyteryda Nyteryda

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    I'm too scared to take it over 5k as I obviously dont want to damage anything .. I am stunned that the 450s they sold me are, by general consensus, nowhere near whats needed.

    I believe the a/r of the turbo is 0.60.. unsure of which boost level it has been mapped to atm, i have a dyno sheet which i will upload later this evening
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  14. Prawn
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    Prawn My other car is a MINI!!!!

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    It seems to vary so much, but generally, 440's on ME7.5 seem to max out around 300-320bhp.

    Oddly, on my me3.8, they are fuelling much much more, and seemingly happy doing so, where on ME7.5 cars they start to go lean when pushed this far, but on mine they just keep on giving :S
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  15. Nyteryda
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    Nyteryda Nyteryda

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    DSCF0285.jpg
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  16. Prawn
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    Prawn My other car is a MINI!!!!

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    Interesting, so they KNEW it was going lean when they mapped it.....
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  17. Lewis583
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    Lewis583 Active Member

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    Holy lean Batman.

    I'm surprised they did more than one dyno run with it going as lean as that
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  18. Nyteryda
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    Nyteryda Nyteryda

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    After the first two lean top-end runs they decided to take it all the way to the redline on the last one with the a/r ratio still climbing

    He told me on the day that it was best to use injectors that can flow just a bit more than the application requires, in my case he said 450 green giants were the best choice. I did have concerns about this at the time as I had read a lot of conflicting information but he reassured me these were the correct ones to install
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  19. Lewis583
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    Lewis583 Active Member

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    Did the tuning company even attempt to adjust fueling to rid of the lean-ness at the top end? Or did they mention the injectors were at max duty cycle?

    I amazed they would send a customers car out running >stoich above 6000rpm
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  20. s3dave
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    s3dave TFSI Hybrid

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    Yeah 550cc to be safe for a gt28

    it looks like jabba the hut mapped that....:whistle2:
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  21. superkarl
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    superkarl MAN OF STEEL

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    id put the fact prawns isnt leaning out and yours is, down to A. the tuner. or B. your fuel pump isnt supporting the top end. unlike prawns which clearly does.

    id put 630s in and see a more reputable tuner tbh and get it fixed so you can actually enjoy what you've built!

    there are a new range of injectors out called genesis II 600s, try them. its what i want to try
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  22. Nyteryda
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    Nyteryda Nyteryda

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    Yea the guy did say that I needed to increase the fuel supply which I am looking into at the moment, however, I dont think that changes the fact that the injectors they sold me are, by all accounts, too small for the application
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  23. superkarl
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    superkarl MAN OF STEEL

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    but judging by prawns experience that may not be the case. HOWEVER, even if there was a fuel supply issue rather than too small injectors, they should never have let a customer leave with AFR's like that. for that reason, dont use them again.
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  24. Prawn
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    Prawn My other car is a MINI!!!!

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    it's hard to say which it is for sure though, it COULD be the stock fuel pump not able to supply enough fuel, the the injectors are OK. or it could be the injectors. without logging fuel pressure at the rail, it's hard to say.

    at 340bhp, the 440's should be able to cope still, as mine are, and they're clearly not.
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  25. Nyteryda
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    Nyteryda Nyteryda

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    Even if the fuel supply is causing the lean issue, it still doesnt seem likely that i would get 360-380bhp from these 450cc injectors going by what I have been told. The guy who built the car said 440s were too small for his 300bhp motor and he had to put in 550s.. Really starting to get depressed about it all :-( especially with another potential big bill ahead for more injectors and mapping
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  26. Lewis583
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    Lewis583 Active Member

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    Ideally we would need to know what duty cycle the injectors are currently running. If they are maxed then the injectors are insufficient and require upgrading. However if they aren't maxed out then either the map is turd or you have a fuel supply issue.

    A 4bar FPR could be used to squeeze some more cc's out of the injectors but if your fuel pump is on it's last legs, the 4bar FPR will more than likely finish it off all together.
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  27. Nyteryda
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    Nyteryda Nyteryda

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    ok, i guess i need something like vagcom to log the injectors duty cycle ?
    #27
  28. badger5
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    badger5 RIP S3dave Site Sponsor

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    vcds/vagcom yes..

    when you do, log 001,002,031 so overall fueling can be seen.

    see what adaptions are being attempted by ecu... Fuel pressure may be dipping as well as high duty cycles... although duty cycles may well be max'd....
    #28
  29. Prawn
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    Prawn My other car is a MINI!!!!

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    I'd say this is most likely correct. There is every suggestion that your 450's SHOULD be able to fuel the 341bhp you have currently, but certainly not the 360-380 you were hoping for.

    I must admit though, given the prices charged by most tuners are now very similar, and the reputation of a few good people on this board, it does still surprise me to see people going elsewhere, this isn't the first problem is this nature that's been brought up recently either....
    #29
  30. Nyteryda
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    Nyteryda Nyteryda

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    I went to this particular tuner as it was recommended to me by my (engine) builder, he regrets suggesting it now but hadnt had any problems before so he wasnt to know .. It was a bad experience right from the start as I was booked in for 9am, got there at 08:50am after leaving home at 05:30am and they didnt even touch my car until 10:45am
    #30
  31. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    So was the tuner jabbasport then?
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  32. Prawn
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    Prawn My other car is a MINI!!!!

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    I think that's pretty clear from the dyno graph Dani ;)

    Old school tuning, they need to move with the times, or they're going to get left behind....
    #32
  33. Sam_
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    Sam_ Down under

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    How do you mean old skool tuning? Surely fitting injectors too small and having the engine run lean has always been bad (or jets too small for carbs - now that's old skool ;) )
    #33
  34. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    My bad haha, didnt study it. Well it says it all doesnt it then, jabba need to do everyone a favour and stop bloody trading, their useless, every thread ive read, be it in here or elsewhere that involve jabba is juat issue after issue.
    #34
  35. Nyteryda
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    Nyteryda Nyteryda

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    Another query for you guys .. When the s3 went for the base map the guy didnt want the n75j on the car and asked me to replace it with a standard valve for the custom map, he then electrically disconnected the valve in the meantime while i ran the engine in. I of course replaced the valve as requested, and due to a temporary lack of a port it couldn't be connected to the intake (post-maf?) with only the diverter valve and post-turbo pipes connected up. My questions are what effect does it have running without the n75 connected to the intake, and can it be mapped properly in this state ? I assume there is a loss of metered air .. ?
    #35
  36. badger5
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    badger5 RIP S3dave Site Sponsor

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    N75 J is a "spikey" valve, so not the first choice... but it could be mappable with it.. Maybe they cant control the spike howeve.... *cough*

    Short term, N75 venting to air as opposed TIP makes no odds to its function so long as the other 2 ports are connected correctly.
    why does your tip not have a suitable port??
    #36
  37. slappy_dunbar
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    slappy_dunbar Let's Do This

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    I'd say your first step is a stronger fuel pump system.
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