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custom Made Exhaust System

Discussion in 'A4/S4 forum(B5 Chassis)' started by Nez, Aug 19, 2009.

  1. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Lol, i just get pissed off with people trying to claim huge performance advantages from some random youtube video. Post a dyno plot, a quarter mile time or even a FATS time then i'll take heed.

    To satisfy your query, 305hp would give around 12.75 secs and 350hp would give around 11 secs

    I never claimed the calculations were going to be accurate, they're simply a guide, but a reasonable one at that. Website is here: http://www.letstorquebhp.com/calculator.asp

    I would suggest that pushing 350hp from some K03's would require more than just a remap and a boost controller (cant the ecu do that job?). Perhaps with some very shiney intercoolers, sport cats and a excellent exhaust system you might manage somewhere close, but for how long?
    #81
  2. Lee Goodall
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    Lee Goodall ..got my head together!

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    Well my exhaust definitely might have given me at least nearly 40HP probably.
    #82
  3. s4marsh
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    s4marsh Member

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    thanks bluethunder. all i said was,that i thought the custom map i've had seems pretty good compared to what i've seen on other vids with remapped cars not making bizarre statements that i have the best remapped s4 in the world.my time for 0-120 is just shy of 15 seconds changing gear at no more than 6500rpm and when using a friends vagcom + manual timing recorded an average fats time of 4.1 seconds and max air flow recorded was about 258g/s and 370lbft torque if i remember correctly i could be slightly out. so please dont get all annoyed at me just because you think i'm pulling random figures out of the air are you the gospel on audi's?? my boost management system certainly has benefits like being able to choose my own wastegate pressure and being able to change it when i feel like it increasing torque and plotting my own boost curve to suit my style by running different boost in different gears and at set rpm's so just chill with the agro when you know nothing of exactly what set up i'm running or what temperature it was when filming my times or anything only your experience,...it seems i have a good strong engine but it has been serviced every 4500 mile and meticulously looked after and may have had work done i dont know about like a flowed head or even bored out bigger injectors anything.. although i do have every bill from new
    Last edited: Aug 26, 2009
    #83
  4. s4marsh
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    s4marsh Member

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    another thing to take into consideration is i weigh next to nothing i carry no spare wheel or junk and always light on fuel those 3 factors alone could make half a second difference to 60 let alone 120
    #84
  5. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    As i said, i just dont like random claims based on youtube videos. Facts are good, pub talk is not.

    You've now posted some real numbers, and we see from your MAF figures that your running about 322hp (using the 0.8 multiplier), which is perfectly reasonable for a custom map on K03's

    The FATS time does seem a bit low when comparing it with the figures here though:
    http://fats.audi-quattro.org/

    Most times around 4.1 seem to be from K04'd cars running stage 2 or 3, although there are a few 4.6's from people on K03's with the spare etc removed.

    I've never heard of the boost control system you mention, but i'd have thaught the ECU would start getting pissed if it wanted, for example, 18psi, and your controller was set to 15 (or 20)?
    #85
  6. Dan Gliballs
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    Dan Gliballs Active Member

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    Indeed.

    My S4 hits 190 in a very low specific time for sure I think.

    No need to doubt me as my sundial never lies.
    #86
  7. Blue_Thunder
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    Blue_Thunder Active Member

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    My best FATS times in my K04'd S4 is 3.8, so 4.1 is truly quick for a K03 car.

    One thing to bear in mind is that BHP is not really that important in the grand scheme of things, it's the torque that's important. FATS is a much better measure of how quick an S4 is than max power.

    An example is on a RR day I organised last year I got 415bhp and another guy got 430bhp. Doesn't sound like there would be much in it on the road from those figures, but from driving his car I knew that his would absolutely spank mine if they were put side by side.

    The reason??? My peak torque figure was 440lb-ft, his was 530lb-ft!!!

    It's all about that area under the curve. The benefit of running something like the Turbosmart is that you can increase the boost and therefore the torque above and beyond the map's pre-defined levels. It probably pushes the turbos harder than a tuner is willing to take responsibility for (after all, who would go to a tuner if all the cars they mapped exploded?), but it's the car owner's choice if they want to wind the boost up. Tuners have to err on the side of caution for reliability purposes, manufacturers even more so.
    #87
  8. Dan Gliballs
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    Dan Gliballs Active Member

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    I gave up revving my S4 that high yonks ago.

    Very little extra happens above say 5800rpm IIRC.
    #88
  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Blue: While he may have a higher peak torque and a larger area under the graph overall, wouldnt you agree that its the area under the graph in the zone where your actually accellerating that matters?

    In a "race" your going to be up around 5-7krpm, and in that region i really dont think there would be much difference in the area under the graph on both cars (because if there was his peak power would be much higher). I suspect he has a really large boost spike in the midrange giving this inflated torque figure, but the engines clearly not holding onto it because its power figure isnt much better than yours.

    People go on about torque, but in reality, in a race, power is which matters. The reason for this is simple, if you take two steady state torque figures, 1000lbft @ 2000rpm and 500lbft @ 4000rpm, if only torque mattered then the first figure would be twice as good, but its not, becuase the engines doing half the RPM. They're both producing the same power, and as such the accelleration would be identical (at that particular point in the rev range).

    Derv motors make HUGE torque figures, but again its all at the lower end of the rev range. When you factor RPM into account you find that while its making much less torque at 3000 rpm than 2000rpm, its making more power, and therefore will accellerate quicker at 3k than it will at 2k, becuase the engine is producing more energy at 3k.

    Dan: While it may not feel like it, the S4 doesnt make max power untill quite a way past 5800rpm, and if your not reaching max power your not extracting the max from the car.
    #89
  10. Dan Gliballs
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    Dan Gliballs Active Member

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    Say what?

    [​IMG]
    #90
  11. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    Interesting, but you need to consider how much the RPM's drop on a shift to optimise the area under the graph.

    If you shift at for instance 5750, and the revs dropped 1500rpm (this is a guess) you'll be down at 4250 for the next gear. If you instead revved it out to 6250, then it would only drop to 4750, and the average power delivered (area under the graph between the two points) would increase?
    #91
  12. Dan Gliballs
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    Dan Gliballs Active Member

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    I DO!!!

    Why do you assume that people don't know anything? lol

    After three years I have a fair idea of the fastest way to accelerate from the M6 Toll barrier ;)

    I've heard plenty of talk about it being pointless to hang on to the revs in an S4 in drag situations etc. Slightly different matter on K04's though.
    #92
  13. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    You've just said you shift at 5800, and looking at the graph you posted, thats quite likely to mean your RPM's will drop far enough for it no longer to be in the optimal zone?

    The peak between 5250 and 6250 is surely where you want to be, as the average power in that area is higher than the average power found between 4800 and 5800.

    I'm not saying you dont know anything. I'm simply analysing the data you've provided and telling you what i think.
    #93
  14. Dan Gliballs
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    Dan Gliballs Active Member

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    I don't stare at my rev counter waiting for 5800rpm no, it was off the top of my head earlier, and after I dug that graph out it confirmed that I wouldn't really NEED to go beyond that. Most of the optimum gearchange stuff is done by 'feel' with most people. My main point still stands that I certainly wouldn't rev MY S4 to 6500rpm.

    It also confirms that you were incorrect on the peak-power point on an S4. I'm simply analysing the data I provided ;)
    #94
  15. jcb
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    jcb Active Member

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    depends if I am in a hurry but I usually know I have just missed the optimal shift point when the limiter cuts in!
    #95
  16. s4marsh
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    s4marsh Member

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    this has now turned into a proper discussion now which i appreciate, aragorn have a look at these boost management devices "Turbosmart Eboost2" its not just a basic controller. i agree with you 100% that my recorded fats time when compared to the rs246 chart seems out of sync like you say stage 2+ territory when i'm just a remap+vpower and tweaking to the ic shrouds and foglight removal which puzzled me too and i cant explain it other than possibly an above average remap or a strong engine but 67k is pretty low and well looked after or not even run in yet for an audi depeding how you see it. my peak boost is set to around 17.4psi at the moment and it hits that @ 3000 ish rpm and last time i checked it doesnt really drop off that much like i thought it did, this might not be very good for the turbo's at all and severly reduce there lifespan i dont know, but garanteed to find out its all fun...some turbo/engine software i have from the rayhall turbo site claims i should be making around 330bhp at that psi i think but more than happy to accept your conversion result of 322bhp download the instruction manual pdf for the new eboost2 controller from their website its got tons of options which i'm sure you'll understand better than i do, i think this unit plays a part in making my car quicker than it should be for whats been done to it and as i'm the only person i have heard of on any audi forum with this fitted to an s4 its very difficult to compare or predict outputs and specs like for like
    #96
  17. Nez
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    Nez Member

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    Man whats wrong with guys look what you guys did to my thread :( couldn't you guys opened another thread to talk about this things and why on my theard this not fair :(

    :sign_ot::sign_ot::sign_ot::sign_ot::sign_ot:
    #97
  18. s4marsh
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    s4marsh Member

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    ha ha ha ha ha ha thats whats happens man i love it ,but dont complain nez your reading absolute gold dust here from people who understand s4's and tuning in general way more than me or you so sit tight and you might learn a thing or 2 that'll be useful to you in the future and you might end up with more than 249.1 bhp if your a good boy
    #98
  19. Nez
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    Nez Member

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    My S4 isn't running well at the monent but keep your eye on that 249.1 bhp :hubbahubba:
    #99
  20. dieselfitter251
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    dieselfitter251 Blow ma own trumpet?

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    Love it!
    :grabs a beer: Wish I was reading this last night instead of Italian Job americano stylee......
  21. Nez
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    Nez Member

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    Lol :)
  22. s4marsh
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    s4marsh Member

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    somewhere near the original topic an rs4 exhaust has just sold for £72 on ebay giving an s4 probably the same benefits as a aftermarket system would i reckon?? i'm in the process of doing a deal on a 2nd hand rs4 full turbo back standard system to gut the precats and fit if i can sort some money out soon
  23. Nez
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    Nez Member

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    RS4 has 200 cell cats in the downpipes as standard :)
  24. s4marsh
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    s4marsh Member

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    well done, see you did learn something didnt you....lol

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