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turn up boost

Discussion in 'A4/S4 forum(B5 Chassis)' started by welchy29, Oct 16, 2010.

  1. welchy29
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    welchy29 New Member

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    [Oct 16, 2010]
    hi there does any body know how to turn the boost up on a a4 1.8t think its a b5 (y reg) 2001...its all stock only had it 4 days.....just want to know if its poss and how to...many thanx welchy
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  2. Oranoco
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    Oranoco Well-Known Member

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    [Oct 16, 2010]
    Remapping or chipping is the only way. The electronics control boost, any form of bleed valve or dawes device will be compensated for by the ECU and the boost returned to predetermined level. DIY boost upgrades are never a good idea though as you must have the fueling there to work with any increase in boost or very quickly it ends in "bye bye engine" and lots of ££££'s
    Last edited: Oct 16, 2010
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  3. CHRIS555
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    CHRIS555 DOPE with added OCD

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    [Oct 16, 2010]
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  4. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Oct 16, 2010]
    MBC will just cause it to drop into limp mode, as soon as the MAF detects more airflow than stock it will cut all power.

    You need to remap it for any meaningful gains.
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  5. evilscotsman
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    evilscotsman Space Cowboy

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    [Oct 17, 2010]
    the tiny turbo on the 1.8T is almost out of its depth anyway mate but honestly the guys are spot on, the only way is a remap. I t doesn't need repeated by me to make it true, but thousands ask the same q and I always felt my 1.8T was strained as standard and pushing it would lead to failure.

    they most certainly are not bulletproof like some sellers would have you believe. worth considering that on a standard engine the compression ratio may be say, 12:1 - so with no turbo boost it will compress atmospheric air (14.4 psi absolute) to 12 x 14.4 ie = 172 psi peak cylinder pressure, so then add some boost to +14.4 psi (+1 bar) from a turbo, now you have 12 x 28.8 psi = 345.6 psi P.C.P.

    Now, up the boost to 20psi, just 6psi more, and you get 12 x 34.4 = 412.8 psi - an increase of 72 psi at the piston crown....so any boost increase at the intake is multiplied by the comp ratio resulting in a large increase in peak cylinder pressures.

    as well as the increased stress on the internals it requires more fuel to go with the increased air so stoich burn ratio can be maintained (even more fuel may actually be needed on top to act as a charge coolant) since if it runs lean at high pressure it can melt through piston crowns quickly during a caning as peak pressures are huge, temps are high, and the only way to increase fuelling is to reprogram the ecu.

    boost and fuelling must go hand in hand or bad things happen bud :(
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  6. murran
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    murran Active Member

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    [Oct 17, 2010]
    bent conrods too!
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  7. welchy29
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    welchy29 New Member

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    [Oct 17, 2010]
    thanx for that boys...o well think al just keep it standard,just got a bit giddy we it been me first turbo..dint know they were so temperamental....lol
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  8. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    [Oct 17, 2010]
    They're not tempramental, just needs done right.

    There are people on ebay who'll do you a remap for £100 if you post them the ECU.
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  9. evilscotsman
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    evilscotsman Space Cowboy

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    [Oct 18, 2010]
    aye we're saying a remap is fine, that increases both fuel and boost and timing properly but dinna turn up boost on its own by yourself thats all mate :)
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  10. tdia4
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    tdia4 TDIPOWARRR

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    [Oct 18, 2010]
    You can get a remapping company to usually come to you for around £250-£300.

    I used Elite remaps for my Diesel, i got it done for £170 but thats because a few of us had it done at the same time, im happy with the results, had the map on about 5 months now and had no problems.
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  11. jcb
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    jcb Active Member VCDS Map User

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    [Oct 18, 2010]
    I wouldnt call it under strain if you can run a much larger framed turbo at low boost and have 350bhp and 300ftlbs without too much concern. plenty of people running 50trims and super60 turbos on stock blocks with proper mapping of course.

    its actually 9.5:1 but your cylinder pressure theory holds. not a major conern unless it is combined with super heated fire rings or detonation.
    think deisel engines at 25:1 stock compression

    OP: It doesnt matter if it is as bulletproof as some people think it is or not, run it lean or run a shitty map on a maxed out small turbo (i.e the one you have) and you will burn a hole in your pistons tops or ventilate the crankcase with a banana shaped rod.

    save your pennies and get a remap
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  12. evilscotsman
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    evilscotsman Space Cowboy

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    [Oct 18, 2010]
    yeah jcb, I was referring to the tiny apple-sized standard turbo which as you know just pumps heat after a certain point on the boost scale.

    The bottom end is pretty good by all accounts as long as no sludging or other oil pressure issues appear which would be the same for any engine, just these are prone to oil pressure failures due to the sludge issue plaguing the 20v turbo motors. (my b6 included lol)

    and oops yeah 9.5:1 (my brain supplied 12:1 which was the mecr figure I saw quoted somewhere for an NA motor, which of course is too high for a turbocharged engine) doh lol

    My point was, anyway, that if you take a standard engine, and turn up the boost, then the bad things mentioned will happen with a bang, that was it really lol
    Last edited: Oct 18, 2010
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  13. welchy29
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    welchy29 New Member

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    [Oct 18, 2010]
    thanx lads al save up a few pennies.....ant got me car back yet,got it thursday night from a local garage had it 3 hours and the turbo blew..getting it fixed courtesy of the garage (brand new turbo) happy days....i hope lol
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  14. evilscotsman
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    evilscotsman Space Cowboy

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    [Oct 18, 2010]
    whoops - better now than later tho, hope they are paying ;)

    on the plus side, new turbo = nice start point with the car from here.
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  15. jcb
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    jcb Active Member VCDS Map User

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    [Oct 18, 2010]
    whip out that brand new turbo, stick it on eBay and get yourself a recon'd bigger one for the same money and you have an even better starting poiint!!
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  16. evilscotsman
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    evilscotsman Space Cowboy

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    [Oct 18, 2010]
    true!
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