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Prawn and BigAls A3 Track Car

Discussion in 'A3/S3 Forum (8L Chassis)' started by Prawn, Dec 29, 2010.

  1. eddieantifreeze
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    eddieantifreeze Member

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    cheers buddy, allthough its quite likely ill be in spain 'working'....

    plus the RS4 is spending a week in the garage having loads of work done under warranty - but either way let me know!
  2. AGU-TURBO
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    AGU-TURBO Audi a3 1.8t AGU

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  3. Paradox1
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    Paradox1 Active Member

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    He has a 3 inch maf from a vr6 and 440 injectors I believe.

    Prawn I need an update lol
  4. AGU-TURBO
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    AGU-TURBO Audi a3 1.8t AGU

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    Yeh thats why i was asking as the vr6 maf is 2.75" which is good for 310cc injectors. i thought on the agu the bigger injectors you have the the bigger maf. Somthing like this:

    (Taken from another forum Nick at R-tech had posted)

    Stock is 2.44" inner diameter good for 240cc

    Vr6 maf is 2.75" inner diameter good for 310cc yellows

    3" inner diameter good for 360cc

    3.25" inner diameter good for 440cc
  5. beachbuggy
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    beachbuggy Well-Known Member

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    All that happens is the bigger injector you have the more power the engine can make, but to make more power you need more air flow through the maf. The stock AGU maf has a limit Of around 185g/s at this flow the maf sensor gives aprox 4.98volts which is its max voltage. Now if you put that sensor in a larger housing 185g/s now may only be 4volts and the max 4.98volts might 235g/s so confusing the ecu as it thinks less is going through the maf than actually is. In order to over come this you need to rescale the maf to accommodate this air flow. In theory you could put a big maf diameter on small injectors and scale but if say you only run 175g/s but the maf can flow 250g/s then you'll loose accuracy as its like trying to measure 1 pint in a swimming pool compared to 1 pint in a 1 pint measuring jug. For the best results you need to match the max airflow with the capability of the maf housing. Bigger isn't always best. Not sure if this has any relevance to your post or what you where enquiring about but hope it helps
    666markyboy likes this.
  6. AGU-TURBO
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    AGU-TURBO Audi a3 1.8t AGU

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  7. Prawn
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    Prawn My other car is a MINI!!!!

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    Yo folks!

    Agu dude: those figures you've posted sound more like BHP values than injector sizes, standard maf will see 240bhp, VR6 maf just over 310bhp etc etc.....

    Either way, I'd just go with exactly what Niki says, if he's the one mapping it, then he knows what's going to work best with how he writes his software, so just keep him happy :p


    As Paradox said I'm running a Vr6 80mm MAF (not sure on internal size) with bosch 440cc injectors.

    Sadly no big updates folks, it seems that my O2 sensor location has caused a few issues and the car started doing funny things on Friday. It's start off fuelling perfectly, then over a few runs lean itself off from 12.4 to 12.8-13:1 AFR's. Seems like this is an issue with the sensor either being faulty or badly placed by me.

    WIll be investigatesd further tomorrow apparnetly, once Niki has fixed the bloody water leak it decided to spring!
  8. badger5
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    badger5 RIP S3dave Site Sponsor

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    hows your fuel pump nick?
    pressure holding ok?
  9. Prawn
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    Prawn My other car is a MINI!!!!

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    As far as I know it's doing just fine Bill, Nick said the problem seems to be after the adaptations have taken place that the LTFT's seem to lean it off a tad.

    Fuel pump is a low mileage LCR unit, so providing it's in good shape it should be fine for my needs. Especially as I'm on low boost so not asking it to supply LOADS of pressure.

    Just want to drive it now! Will add more when I get an update from nick :)
  10. superkarl
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    superkarl MAN OF STEEL

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    prawn how do you have your car set up geometry wise?
    just wondering how extreme you have it for the track, and whether you've given it much thought.
  11. Prawn
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    Prawn My other car is a MINI!!!!

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    To be honest dude, there isn't that much that's adjustable on the LCR running gear, so it's nowhere near as aggressive as I'd like!

    The front camber is pulled as wide as it will go on the ball joint adjustment, which gives me about 1.6 degrees negative on each side, the front subrfame is centred and pushed as car forward as it can go to give maximum castor. Ride height is set fairly sensible with about a 40mm drop to keep wishbone angles sensible, and the rear end is fixed!

    Rear wheels are sat at around 1.4 degrees negative naturally at my ride height, and it's got slight rear toe in, which I'd like to erradicate with shims at some point, but for now that can wait.

    At the front I'd like to be able to add some more castor, but not sure if I should go about this with USRT style adjustable lower arms, or adjustable top mounts.

    For now though, it feels good, and very stable, so I'll keep it as it is whilst we get used to the extra power :)
  12. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    Nick, what do you reckon to the oz's? Ive been offered a set for £150 delivered. Would you recommend them?
  13. S3 Paul
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    S3 Paul Active Member

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    Which ones??
    What size?
  14. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    super turismo's, 17x8, so ideal size.
  15. Dani_B19
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    Dani_B19 Audi-sports own special child.

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    Didnt mean to dislike your post mate, bloody computer.
  16. Prawn
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    Prawn My other car is a MINI!!!!

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    at that price you can't go wrong mate! That's crazy cheap.

    they're not the lightest wheel around by any means, I think they're about 10kg per rim, but they're still over 2kg per rim lighter than the standard rims, and they look brilliant.

    I was surprised to find that mine looked much better on the car in the flesh than they do in pics. they sit really nicely i the arch, and look really purposeful :)

    If you don't buy them, let me know where they are and I will!
  17. moredoor
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    moredoor Member

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    Any more news on the odd fueling issues? I see that you're using the old green top 440cc injectors, these have a single spray type pattern for single valve heads not multi valve heads. check link shows greens spray pattern

    Injectors : USRT, Usually Sideways Rally Team
  18. Prawn
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    Prawn My other car is a MINI!!!!

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    Yup, I'm aware of that dude, but a compromise has to be made somewhere, so where do you make it?

    If I use genesus / bosch 550's with the correct spray pattern, the injector drivers in my old me3.8 ECU are wrong, and you get latency issues leading to ruch running off boost, and poor idle which makes it sluggish and delays spool up, as well as effecting economy.

    If I use the older 440's, they work perfectly with the ME3.8 injector drivers, and nick is able to tune the AFR perfectly across the whole range, both on and off boost.

    I know that technically the spray pattern is incorrect, but it still achives a nice clean burn with perfect AFR's across the range, and to date it's making more power than any other similar hybrid out there at a given boost level, so surely it's not a huge deal.

    lesser of the two evils is the way I see it :) Thanks for pointing it out though :)

    the ME3.8 ECU is so massively different to the ME7.5 to tune :(

    It sounds like my fuelling issues have been down to a strange MAF. nick tried my MAF on another car yesterday, and within minutes the LTFT's went out of whack just like they do on mine. That coupled with my schoolboy error of mounting the o2 sensor about 4' from the turbo isn't helping matters!
  19. sportstractor
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    sportstractor Chugger

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    Quote from r tech niki on sams Facebook page

    "it's more like tuning a gt28 at the top end"

    That just tells you it's going to be wild when it gets unleashed after rods
  20. badger5
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    badger5 RIP S3dave Site Sponsor

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    the 2283 comp wheel is comparible flow wise... so thats expected
  21. R-Tech-Nick
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    R-Tech-Nick Member

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    The AGU & M3.* ECU has huge scope to tune, just takes a lot longer than the Me7 ecus.

    The issues with scaling on the m3.8 ecu is that every thing is based around MAF and injection ms, The min injection, start injection and voltage latency offset is easy to setup, but then recaling the main ecu constant for injection all the load map axis scale wrong which means timing and load maps are a mile out. It not as easy of setting a 1x1 injector constant and pasting a vr6 maf scale in the map then carry on mapping.
    Me7.5 is easy and has enough scope for huge injectors and maf with only a few map changes and all the load map scales just need the upper limit changing and job done.
    The best way to tune the m3.8 is try to do as little correction as you can with the software, get the maf size scales close to injector size increase % which then allows for minor % correction to the part throttle maps and main constant injector map based from log on the current fuel a fuel trims, then less work on the map scales, just bringing the timing map back into check then start tuning

    I have tuned the same engine, ecu injectors and MAF to 411bhp on a £150 T304e. Its now running 630cc at 424bhp and 480bhp with NOS and has left me no more scope on the ECU scales, so next mission is a 3.75" maf to unlock the map a little more.

    Run with 17psi with stock rod and 440cc Bosch 2.75" maf back in 2010

    [​IMG]
    [​IMG]

    Run with 440cc Bosch 2.75" MAF 411bhp 27psi
    [​IMG]
  22. beachbuggy
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    beachbuggy Well-Known Member

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    Stock rods. Wholly cow! Well there's an advert for stock rods doing big power. Although if one let go at 424bhp NASA would be picking bits of the engine up off the moon on their next visit!
  23. Jason.s
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    Jason.s Active Member

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    That manifold is epiiiic
  24. badger5
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    badger5 RIP S3dave Site Sponsor

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    nice 1000rpm power band.. hehe
  25. R-Tech-Nick
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    R-Tech-Nick Member

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    #

    Thats as much as we can run with the 440cc we could not hold the power and longer, with the 630cc we had 424bhp at 7100rpm.


    It a budget 1/4 mile sprint setup with the 440cc injectors it was running 12.3s @ 121mph, In the real world its a quick car and ended up 27th out of 145 in the Santa pod street cup 2011, and took fastest car in class on the VAG Pod shows 2011.
  26. R-Tech-Nick
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    R-Tech-Nick Member

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    lol another moon landing.

    What power have you tested stock rods to? I have tested AGU rods to 350bhp, and happy to tune them to 300-320bhp with toque under 300lbft.

    The 400+bhp runs are alll with uprated rods.
  27. Prawn
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    Prawn My other car is a MINI!!!!

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    300 will be more than enough for me! Can't wait to drive it :)
  28. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Its cylinder pressure and the associated boost spikes that tend to do the damage Nick... so boost and timing advance plus pot luck tbh...

    This has been debated quite a few times on this forum and generally leads to a bun fight (so I will remove any such debate from this thread as its about Prawns car...) so many factors but these cars are old and generally high mileage so its all a matter of when rather than if...

    As long as the torque is brought in smoothly rather than with a bang and timing wise there is nothing to shock the rods when boost kicks in then they should survive... for now! ;P

    <tuffty/>
  29. badger5
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    badger5 RIP S3dave Site Sponsor

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    good for what its been built for I suppose

    horrible for a road car.... such narrow power band
  30. badger5
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    badger5 RIP S3dave Site Sponsor

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    thing is Nick.. No fixed figure will account for wear and tear and more importantly fatigue.
    you are brave if you fix a figure on stock rods being safe... There is'nt one imho
  31. slepy
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    slepy Well-Known Member

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    Is it normal for T304e to have such a narrow power band?
  32. Jason.s
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    Jason.s Active Member

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    As Nick said the injectors were limiting the power band and when upped in size more power was available.
  33. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Its a fairly huge "old school" turbo, so i wouldnt expect it to spool much earlier than it does.

    Most people using a turbo that size would tend to have it hold the power to 8k+ instead of tailing off where that plot shows, presumably due to the injectors!
  34. slepy
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    slepy Well-Known Member

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    Probably that's why it's cheaper than a GT2871...
  35. Prawn
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    Prawn My other car is a MINI!!!!

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    Just had a call from Rob at R-tech, and apparently it's ready!!!!!

    More to come later :)
  36. Westy
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    Westy Double Dark Side! Diesel & 8P

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    I bet you feel like a teenager about to get laid for the first time :)
  37. moredoor
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    moredoor Member

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    Cool! can't wait to read/see the results
  38. Prawn
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    Prawn My other car is a MINI!!!!

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    I'm not completely sure I'm going to be able to wait until saturday to go and get it, it's going to kill me!!!
  39. Westy
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    Westy Double Dark Side! Diesel & 8P

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    Can you not collect it during the week? Try and wangle a half day from work.
  40. Prawn
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    Prawn My other car is a MINI!!!!

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    I could do yea, but Tori and I are going up that way on Saturday anyway, and will be just 20 mins from Rtech, so it seems kind of silly to make the same journey twice!

    if I wangled a half day off work I'd need a mate to drive me up too! So a bit of a logistical nightmare.

    I could go after work and be there by 9, but obviously Niki wouldn't be there himself! So that's no use.

    I think waiting now it's done will be even harder than waiting whilst he was mapping it!

    So excited!!! argh......!

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