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Diesel centre box and back pressure

Discussion in 'A4/S4 forum(B5 Chassis)' started by tdia4, Feb 25, 2011.

  1. tdia4
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    tdia4 TDIPOWARRR

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    [Feb 25, 2011]
    Thought i would post in here as nobodys seems to use the diesel section.

    The baffles in my centre box have collapsed and instead on replaceing the box im planning on having it removed because its about half the price, its only the centre box that will be removed and that cat and rear box will still be there.

    Now I was thinking am I going to loose performance from doing this? Due to not as much back pressure or will that cat and the rear box provide enough back pressure still?

    The cars a a4 b5 1.9tdi 110, chipped to 140-145bhp with egr blanked off.
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  3. Jason.s
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    Jason.s Active Member

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    [Feb 25, 2011]
    It may be a diesel but its still turbo so really you dont need backpressure. The milltek systems for the fabias and ibiza diesels dont have centre boxes so it gives them a better sound.
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  4. tdia4
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    tdia4 TDIPOWARRR

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    [Feb 25, 2011]
    Ok cheers, think i'll go for it then.
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  5. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Feb 25, 2011]
    ditch the cat while your there.

    After the turbo you want as little back pressure as possible.

    Removing the cat will allow the engine to spool up quicker and should flow a bit more air too.
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  6. ScottD3
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    ScottD3 I want your faulty electronics

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    [Feb 26, 2011]
    Jack,
    After the chip hows the MPG doing?
    was it worth it?
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  7. fARQUARE
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    fARQUARE Member

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    [Feb 26, 2011]
    I have an afn, also chipped and even through the winter i'm getting 55mpg plus on biodiesel and 200k worn injectors.
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  8. ScottD3
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    ScottD3 I want your faulty electronics

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    [Feb 26, 2011]
    Thats bloody good.
    I thought I was getting good MPG with a standard AFN engine with 118k.

    Is it running ok on Biofuel?
    I've put 40 litres through with 20litres of normal diesel and it seems ok.

    what was the MPG before the chip?

    Sorry to hijack the thread jack. :)
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  9. tdia4
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    tdia4 TDIPOWARRR

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    [Feb 26, 2011]
    My current average is around 54mpg, not sure what it was before.

    Transforms the car completely though, when I got the car I thought it was pretty sluggish, not sure if there was something wrong with it as alot of people say the 110 is quite nippy standard, maybe I didnt feel it as i've has some pretty quick cars in the past, anyway the power was all between 2-3k rpm then it would just trail off, after the chip was done it starts pulling at around 1.5k rpm and pulls well to like 4k rpm, noticeable difference and well worth it, yeah its not going to win any awards for the fastest 0-60 or anything but i've been suprised at what ive been able to see off in it, 2.0L petrol laguna, 2.0L td Volvo-newish one.
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  10. ScottD3
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    ScottD3 I want your faulty electronics

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    [Feb 26, 2011]
    That's amazing.
    In getting between 40 and 47 but mine is an auto, so I would not expect much more from it.
    Be nice if I could though.

    Any one got any ideas if it would cause any damage to the gear box?
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  11. fARQUARE
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    fARQUARE Member

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    [Feb 26, 2011]
    i wouldn't have thought re-mapping would have any effect on your gearbox although i'm now expert on autos.

    mpg before my remap was in the same ball park, although i'd caveat that by saying when i got the car the n75 didn't work (no turbo), all vacuum lines were shot, the inlet mannifold was about 95% clogged up and the whole thing was in need of a bit of love. The most noticable difference was it was slow as a dog.

    After sorting all of the above and re-mapping i'm pretty happy with the performance and economy balance. As mentioned above the point to point perfornamce won't win any awards but once on the move it pulls like a good-un.

    I've said it before but i think 70-100 in the tdi would be quicker than in my previous re-mapped 1.8t (in 5th).

    Car runs fine on bio, only issue was it freezing up in the -15 we had here for 3 weeks before x-mas. Change the fuel filter every 7k miles (along with oil, air and oil filter - today's task!) and the only difference is and extra £20 in your pocket every week (assuming a full tank) and a pleasant smell occasionally at lights.
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  12. ScottD3
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    ScottD3 I want your faulty electronics

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    [Feb 26, 2011]
    Thats cool.
    Remap seems the way to go for extra MPG.

    You running to much palm oil in your mix?
    we run about 30% palm in our mix and its been fine over the winter. I only just started using it in the Audi, Use to run the land rover on it.
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  13. fARQUARE
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    fARQUARE Member

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    [Feb 26, 2011]
    no palm oil but did use a few litres of petrol on a full tank to as a poor attempt to stop it waxing
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