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tdi tuning questions

Discussion in 'A4/S4 forum(B5 Chassis)' started by tara_nta, Oct 26, 2011.

  1. tara_nta
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    tara_nta Member

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    [Oct 26, 2011]
    Hi,
    ive recently bought a 1999 a4 tdi, im pretty sure its the 110bhp model.
    Apparently its been 'chipped'. What else could i do/change to squeeze a few more horses out of it without damaging the bank balance too much? Lol

    i was thinking egr blank plate. . . . . . . . Worthwhile?
    De cat. . . . . . Much difference?
    More boost? Mbc?

    Thanks in advance
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  3. tonya4
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    tonya4 TDi Powerrrr

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    [Oct 26, 2011]
    egr blank and de-cat are both worth doing,I guess next would be a fmic or exhaust.May help if you give what engine code you have.

    tony
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  4. ScottD3
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    ScottD3 I want your faulty electronics Supporter

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    [Oct 26, 2011]
    EGR blank is worth it, if not for the any extra gain but it is for the fact it stops exhaust gasses back in to the engine.
    Plus they are only £5 off ebay.

    De-cat is next for me and then a remap I think.
    Not sure if the auto box will handle it though. :)
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  5. adamss24
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    adamss24 Well-Known Member

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    [Oct 26, 2011]
    I will get a set of bigger nozzles and have them pop ballanced and fitted to your injectors, that will give you up to 20 Bhp on a stock engine without a remap. Depending on the size of the nozzles you might need to adjust the IP quantity at iddle otherwise the engine might shudder- that will clear some smoke at WOT and transform the wasted fuel from smoke into useable power. There are many tuning options for the AFN/AVG 110 Bhp, aftermarket cam will unleash 15-20 Bhp, a bigger pump head will allow for more fuel and the obligatory upgraded turbocharger. GT1749Va from the PD 130 drops in and is good to up to 170Bhp with supporting fueling mods. Then there is the bv43 off the 2.0 Tdi 140 Bhp engine which is good for 200-210 bhp. Anything more and you'll need to port the head, upgrade the valves and fit a lift pump so the main pump does not get starved of fuel at high revs. Stock intercooler is good to about 170 Bhp so i would only upgrade if your target is beyond that... It looks cool as feck though !
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Oct 26, 2011]
    Given a diesel flows about 40-50% more air than a petrol for a given power output, theres no way the stock intercooler can happily cope with 170hp's worth of air on a derv.

    Its getting out of its depth at 180hp on a petrol engine and a derv is only making about 130hp with that airflow.

    The fact Audi fitted two intercoolers to the v6 models making 150hp somewhat supports that too!
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  7. diffas
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    diffas Member

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    [Oct 26, 2011]
    With stock head, dss ultime 2 nozzles, gtb1756v you get around 230hp/500nm. That sure includes fmic and clutch upgrade.
    After that serious mods needs to be done, better cam 260/9.5mm, bigger distribution head, ported head and maybe even add gridle.
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  8. adamss24
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    adamss24 Well-Known Member

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    [Oct 26, 2011]
    A stock turbo when it's working overtime will became effectively a heat pump so the EGT increase sharpish. With a larger inter cooler you maintain bhp not make them. The a4 v6 tdi has a twin inter cooler set-up because the engine bay is too small to have a decent FMIC and they have used parts from the same parts bin (as the s4) just to lower costs. The v6 also have a bigger/more efficient turbo compared to the 1.9 VE Tdi and the air volume ingested is much higher hence the stock twin intercoolers. With the a6 v6 tdi they have fitted a FMIC which is a litle more efficient but the oil/water temps are much higher compared to the a4 as it restricts air flow. As i said, the stock intercooler on 1.9 VE tdi is ok to 170 Bhp after that it became heat soaked and will need upgrading. I don't wanna start an argument but fmic are usually worse than the stock intercoolers and the turbo has to work harder to push the air trough the core and piping and keep the same PR as the engine requires... A more efficient turbo is often a better solution than a fancy inter cooler. As diffas said, head, turbo,injector nozzles, will take you beyond 200 Bhp after that you need a really good tune and rods, block girdle, lowered CR pistons and better head/rod bolts. Larger pump heads don't like high revs and expect decreased reliability. Doubling the factory power output is very hard on the engine especially if you drive it hard all the time... I have experienced engine shutdown on my a4 due to fuel starvation and that's with just race 520 nozzles 11mm pump and bv43. I will fit a lift pump just to keep the IP happy...and mine was ok with 180-200 Bhp on stock oil (90 Bhp have lower oil cooler than 110Bhp !) and charge cooler on previous a4 !
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  9. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Oct 26, 2011]
    my point is this.

    The 2.5TDI has a larger more efficient turbo than a 1.9tdi, yet even with that larger more efficient turbo, Audi fitted two intercoolers for 150hp.

    If the standard single cooler can cope with 170hp from a 1.9 with a smaller turbo running maxed out as you've claimed, then it can also cope with a larger more efficient turbo making less power, because that would require LESS cooling.

    The fact that Audi upgraded the cooler on the 150hp V6, (and also incidentally on PD150 golfs) indicates to me that its no longer able to cope at those power levels.

    Manufacturers dont waste money. Every penny is accounted for, and if that engine could have run within acceptable tolerances on a single sidemount, thats exactly what it would have left the factory with. When your tuning an engine, you want BETTER cooling than stock, not worse, so your suggestion simply makes no sense.

    The pressure drop over a good FMIC core at high flow rates WILL be lower than the drop over the tiny stock intercooler, so infact a good FMIC will mean the turbo is working LESS hard, as well as the air being cooled more efficiently.
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  10. adamss24
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    adamss24 Well-Known Member

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    [Oct 26, 2011]
    My point is the v6 tdi has a twin cat system and as such is wasting more energy trying to spool the larger turbo with increased back pressure. At low revs the v6 tdi engine relies on the inherent torque it's producing to get the car moving and the gt1749V(a) is much more efficient at low revs compared to the gt2050V as fitted to the v6 tdi. You need to see the compressor maps to see the efficiency before they surge. Anyway, the gt20 is a low pressure turbo the gt17 is a high pressure one. It does not matter how much air you give to the engine, he's not gonna take it all as it's all about volumetric efficiency. The drag caused by 4 pistons, 1 cam and 12 valves is much smaller than the drag caused by 6 pistons and 24 valves. All that increased heat will go into the oil which also cools and lubricate the turbo. All that extra heat will mean a larger rad, a bigger oil cooler and a increased inter cooler which all add to the curb weight. To be honest, i think the twin intercooler system on the v6 tdi is overkill, i think that was intended to be a twin turbo set-up then they changed their mind and just whacked the gt20 instead. If they did twin charged the v6 tdi then it would have been a serious contender to the s4 with less turbo lag and perhaps twice as better fuel economy. Certainly the vp44 can push the required fuel for 300 Bhp but they would have shot themselves in the foot as i'm pretty sure they would not have sold the s4 in such a high volume... Remember that back in '98 audi had the most powerfull and fuel efficient 3.3Tdi CR engine but they kept the aging VE and PD engine for much,much longer as the market wasn't ready for such high performance diesel engines ! Even the BMW had 4L V8 diesel engines in the 7 series and it wasn't that popular outside Germany ! It was just an exercise for them first because the CR technology was too expensive hence the first CR vw available was introduced in 2007. Don't mention the faethon because that's just a borrowed 3.0 tdi engine from the a6 and a4. Back in the day they had even plans to use PD technology on the v6 tdi engine but they dropped it due to lack of space and used the vp pump instead + the petrol prices were low and every petrol head was looking at diesel engines with disgust- It still happens now in the states and uk !
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  11. tara_nta
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    tara_nta Member

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    [Oct 26, 2011]
    Thanks for the advice. Im 99% sure my engine code is AFN, manual transmission as well.

    For now i think il do a de cat, egr blank off and a nice fmic. What prices am i looking at for a fmic kit?
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  12. adamss24
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    adamss24 Well-Known Member

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    [Oct 26, 2011]
    There's no intercooler kit off the shelf for the 1.9 tdi engine but therte are plenty kits for the 1.8T engine... As i said, you're better off upgrading the injectors first then have a remap... As i said, the intercooler is fine up to 170bhp i would get a gt1749Va turbocharger instead for max. performance gain ! Have them fitted before the remap and you'll be grinning all the time !
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  13. Mackers
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    Mackers Member

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    [Oct 27, 2011]
    what nozzles would you recommend for the 2.5V6, as i fancy more horses, for not much money too, also thinking of smashing my cats out too, for a quicker spool up
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  14. PAULF
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    PAULF Active Member

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    [Oct 27, 2011]
    When I used to bugger about with fords, I'm sure that a couple of firms did water-air 'charge' coolers to replace the stock intercoolers on the cologne V6 petrol - it may be worth a look if you are looking seriously as I think they they were generic units.
    They claimed quite a large increase in cooling capacity due to the better cooling efficiency which I seem to remember equated to a bigger turbo fit. This allowed larger/more turbos or cooler intake temps. (cooler temps mean higher density = more air to add more fuel to)
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  15. adamss24
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    adamss24 Well-Known Member

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    [Oct 27, 2011]
    The reason you don't see many water charge coolers for diesels is because they are not that much more efficient compared to the air to air inter cooler and much more complicated to plumb in. Also if you have a leak you're very likely to hydro lock the engine.
    #14

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