1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Increasing longitivity(Engine rebuild)

Discussion in 'A3/S3 Forum (8L Chassis)' started by superkarl, Jan 22, 2011.

  1. badger5
    Offline

    badger5 www.badger5.co.uk Site Sponsor

    Joined:
    May 28, 2004
    Messages:
    7,326
    Likes Received:
    694
    [Jan 24, 2011]
    not the ponies.. the torque and the delivery of it
    and.... timing pull from other issues on the car will generate loads way way higher than tolerable by the engine

    I am seeing a high proportion of 1.8t's come thru here with timing pull issues... and det is what will break your rod like it was a twig!
    #41
  2. S3 Nattie
    Offline

    S3 Nattie Quattro ist für sissies

    Joined:
    May 19, 2009
    Messages:
    1,600
    Likes Received:
    7
    [Jan 24, 2011]
    Ye I do follow you there Paul with the delivery of torque from a BT. But it could be fair to say that rod failure on 1.8T are not solely on remapped cars as some standard fairly lowish mileage ones have gone also. A guy on VAGOC had a rod go which he believes was due to a oil jet on a standard car, but most dont try and follow it through as to exactly why they have failed as they dont just fail for no reason, something wasnt right.

    If my rods when tomorrow I would be gutted "touch wood they dont" but Im not willing to spend the extra money for peace of mind even though im going stage 2 in a few weeks. I dont think the value of my car warrents spending that amount of money on it, but thats me
    #42
  3. tankie2ndrtr
    Offline

    tankie2ndrtr Member

    Joined:
    Jul 13, 2007
    Messages:
    211
    Likes Received:
    0
    [Jan 24, 2011]
    +1 Nattie, I think its something to deal with "IF" it happens :)

    Touches wood for everyone :)
    #43
  4. Welly
    Offline

    Welly VX220 SC Driver :)

    Joined:
    Aug 5, 2009
    Messages:
    10,699
    Likes Received:
    117
    [Jan 24, 2011]
    All I will say is this...

    Revo Stage 1. Intercooler. Bang. 1 x Quasimodo piston.

    [​IMG]
    #44
  5. campbell
    Offline

    campbell Member

    Joined:
    Apr 19, 2006
    Messages:
    714
    Likes Received:
    1
    [Jan 24, 2011]
    Sandip- I payed out for all my work off my own back. The forged con rods compared to standard cast rods, the difference is amazing in build quality and strength. I don't think I was unlucky when my Rods went because I spend a lot of money on the maintenance of my car as an a maintenance engineer by trade I know the importance of good preventative maintenance, I think the remap contributed to my failure and I wasnt even driving it aggressive! But that's my opinion
    #45
  6. Alex C
    Offline

    Alex C Well-Known Member

    Joined:
    Jan 26, 2010
    Messages:
    2,664
    Likes Received:
    159
    [Jan 24, 2011]
    lol, i still agree with you Karl
    #46
  7. <tuffty/>
    Offline

    <tuffty/> Badger 5 Edition Staff Member Moderator

    Joined:
    Sep 14, 2008
    Messages:
    15,898
    Likes Received:
    1,330
    [Jan 24, 2011]
    Trouble is, when it happens its usually a complete new engine build thats required...

    If you are capable of changing the rods yourself then its a no brainer IMO... if you have to pay for someone to do it then at least consider how you drive, mileage of the engine and level of tune...

    <tuffty/>
    #47
  8. JS1500
    Offline

    JS1500 Howdy

    Joined:
    Sep 28, 2009
    Messages:
    1,168
    Likes Received:
    8
    [Jan 24, 2011]
    My opinion is that if you're planning to keep the car longterm and want to have the peace-of-mind, and especially if you can do it yourself, then it's a very sensible thing to do. If you're willing to spend the money without performance gains (not many folk are) then thumbs up.

    I'm not that sensible though, unfortunately, and may well switch car in the near future. B5 RS4s keep calling to me.
    #48
  9. jojo
    Online

    jojo S3 Drift King! Staff Member Moderator

    Joined:
    Sep 4, 2003
    Messages:
    26,150
    Likes Received:
    1,641
    [Jan 24, 2011]
    #49
  10. JS1500
    Offline

    JS1500 Howdy

    Joined:
    Sep 28, 2009
    Messages:
    1,168
    Likes Received:
    8
    [Jan 24, 2011]
    Thanks Jojo.

    And yeah, sorry for the hijack Karl. Although i'm asking due to mine putting out almost 300lb/ft @ 3,500rpm with boost of 27.5 PSI - longevity of the rods being my concern!
    #50
  11. Alex C
    Offline

    Alex C Well-Known Member

    Joined:
    Jan 26, 2010
    Messages:
    2,664
    Likes Received:
    159
    [Jan 24, 2011]
    I think id be driving like a granny if i knew mine was putting that much torque out, and spikey too
    #51
  12. JS1500
    Offline

    JS1500 Howdy

    Joined:
    Sep 28, 2009
    Messages:
    1,168
    Likes Received:
    8
    [Jan 24, 2011]
    Yep, sometimes ignorance is bliss.
    #52
  13. superkarl
    Offline

    superkarl MAN OF STEEL

    Joined:
    Mar 28, 2010
    Messages:
    7,614
    Likes Received:
    1,102
    [Jan 24, 2011]
    Don't worry about hijacking I'm not fussed one bit! It's a great discussion! And one that needs to be had so people are aware of what they are doing to there cars in tuning them when they are 10 years old. Yes, they are superbly made and drive so so well for the miles they clock up, but this doesnt reflect what's going on in the engine.
    We shouldn't try and pin point a reason for failure or decide a point at which to change rods, but realise there IS a growing trend of it happening so it's something we should bear in mind to save us alot of grief.

    I'm thinking the best and most convenient way of combating this would be through regular health checks of boost and timing, making sure it's running safely and theirs no danger of detonation or boost and torque spikes. You can oil change, plug change, pick up clean, oil pump change all you want but if what's going on inside is dangerous all that goes out the window.
    Then a stage 1 and 2 or maybe 3 car can be run safely.
    I think JS1500 car is a fine example of just a stage 1, but still very risky with huge boost and torque spikes, it's probably perfectly capable of same power levels but within much safer perameters. No disrespect to you or your car, it's a lovely car. And I can imagine the torque peaking feels epic, until boom.

    Thanks for all the input people.
    Peace
    #53
  14. Ian W
    Offline

    Ian W Active Member

    Joined:
    Oct 27, 2007
    Messages:
    1,054
    Likes Received:
    7
    [Jan 24, 2011]
    Theres only been a couple of major failures on the forum and this is just a drop in the ocean of all the S3's produced, I wouldn't call it a growing trend lol
    #54
  15. badger5
    Offline

    badger5 www.badger5.co.uk Site Sponsor

    Joined:
    May 28, 2004
    Messages:
    7,326
    Likes Received:
    694
    [Jan 25, 2011]
    I would call it a trend... from the calls I receive and rods I sell to those who have suffered the mishap.

    and for those who have'nt picked up the relevance I posted earlier in this thread..
    Detonation is what is the big killer of rods, and I am seeing >30% of cars coming thru here with significant timing pull, which is det.. and causes immense cylinder pressures..

    an example of the pressures I describe.. race engine, but you get the drift.
    2600psi cylinder pressure... on 26degree ign advance, 35psi boost, big turbo 2ltr 20v. engine builder added 4 degrees more timing, cylinder pressures exceeded 3000psi, broke his sensor and made 10hp in an already 780hp motor..
    Headline, 4 degrees of timing produced >400psi more cylinder pressure on top of an already 2600psi..

    std 81mm piston, 2600psi cylinder pressure, pushes 20,749lb onto the piston/rod = 9411kg acting on it, 9.4tonnes compressive

    now compare "boost pressure" in relation to this force acting upon things alone..
    std 81mm piston, 20psi boost, 159.6lb onto piston/rod = 72.4kg

    too much boost, will cause det from excessive timing for that boost, which is where it can all go horribly wrong, if you see the effect ign has on cyl pressures
    SNAP tastic for poor old rods which have seen the cyclic loads for many 1000's of ups and downs..

    There are more cars with other running issues which are creating this det, than tired rods.. but combine the two and its broken rod syndrome.
    MAF's, lean running, shyte cheap maps which run lean, promote det, airleaks to name but a few I have seen in the past 12months... Add to a 100k old engine, wanting a remap for 1st time, unknown history to the car, and its a hell of a lottery game

    Sorry to sound like a merchant of doom
    Last edited: Jan 25, 2011
    #55
  16. Alex C
    Offline

    Alex C Well-Known Member

    Joined:
    Jan 26, 2010
    Messages:
    2,664
    Likes Received:
    159
    [Jan 25, 2011]
    i like numbers
    #56
  17. Welly
    Offline

    Welly VX220 SC Driver :)

    Joined:
    Aug 5, 2009
    Messages:
    10,699
    Likes Received:
    117
    [Jan 25, 2011]
    Here you are:

    [​IMG]

    :lmfao:
    #57
  18. Alex C
    Offline

    Alex C Well-Known Member

    Joined:
    Jan 26, 2010
    Messages:
    2,664
    Likes Received:
    159
    [Jan 25, 2011]
    8008135
    #58
  19. Essflee
    Offline

    Essflee Well-Known Member

    Joined:
    Mar 26, 2008
    Messages:
    2,031
    Likes Received:
    28
    [Jan 25, 2011]
    Obviously people know my engine went bang, what I will say is my car has been religiously serviced every 10k or year, which ever came first, was on 66k and I don't tear it about everywhere, to be fair I'd be better off ragging it through the gears as opposed to driving reservedly letting the gears ie 5th and 6th pull me up to speed...

    It's not scare mongering, if I had the spare cash and wanted to run as much power out of my K04 again, which plenty of people on here do I'd seriously consider saving for some rods,

    Probably a case for me of 'once bitten twice shy'

    I know it may seem excessive but I'm really considering returning my map back to standard and enjoy the car for what it is, still no slouch, even without the map...
    #59
  20. S3 Nattie
    Offline

    S3 Nattie Quattro ist für sissies

    Joined:
    May 19, 2009
    Messages:
    1,600
    Likes Received:
    7
    [Jan 25, 2011]
    Thats not the true peak gas pressure on a rod though because you need to take into account the inertia force and subtract that from that peak gas force in order to get a true peak gas force. It is the inertia force which causes fatigue failure.

    To get the maximum compressive force on a rod I have always used the ~ force * area * reciprocated mass force. Once you have the maximum compressive and tensile loads on the rod, you can work out the norminal static safety factor for the compressive and tensile loads begin exerted on the rod. This takes into account the bending moment, bending stress and second moment of area. Use equations to get a initial safety factor and a combined resultant and that will give you the info needed to get a safety factor. See if the con rod material used is within tollerance of the UTS of the material.

    This is what I said in leggys thread to do with con rod forces, might be of benifit to someone or if someone cares to extend on it please do.

    "Its the inertia loads which engine designers tend to design their engines around. Con rods are under cyclic loading and experience 2 types of loadings inertial and power loads. Inertia loads look like sin wave curve, tensile and compressive loadings whereas power loads are only compressive.

    Maximum tensile loading occurs when the piston is at TDC on the exhaust stroke and the maximum compressive loading is at BDC after intake or power stroke. Power loads are partly cancelled/offset out due to the tensile loads and the inertial tensile loads are what induce fatigue failure and that's why inertia tensile loads tend to kill con rods."
    #60
  21. badger5
    Offline

    badger5 www.badger5.co.uk Site Sponsor

    Joined:
    May 28, 2004
    Messages:
    7,326
    Likes Received:
    694
    [Jan 25, 2011]
    Nathan: do you copy-paste out of your textbook all your replies :p

    What are you studying again?

    the numbers posted are to elude to people (the non engineering folks, unlike your good self) as to the kind of forces going on in their engines... crude representation of course, BUT, relates boost and ignition timing as to whats more destructive.

    ... now in the real world on 100k mile engines, please explain further how these original design parameters are completely out of the window when there are non-std aspects to the vehicles (aka maps) and wear and tear, running faults..... severe ign timing, det issues etc etc etc

    and sometimes achey breaky engines thereafter.....

    The Rods did not BEND from tensile loads fella.. Compressive aka nearly 10 tonnes of very quick event load just before tdc - Wellys pictures says it all.
    Last edited: Jan 25, 2011
    #61
  22. s3dave
    Offline

    s3dave TFSI Hybrid

    Joined:
    Nov 11, 2009
    Messages:
    10,120
    Likes Received:
    729
    [Jan 25, 2011]
    Lol....
    What about blueprinting an engine?
    #62
  23. S3 Nattie
    Offline

    S3 Nattie Quattro ist für sissies

    Joined:
    May 19, 2009
    Messages:
    1,600
    Likes Received:
    7
    [Jan 25, 2011]
    Im doing a degree in motorsport engineering and design. Not long had an assignment on fatigue and stress anaylsis on con rods, so its fairly freshish in my head lol. The equations I gave above are from my work though lol.

    I would agree with what your saying about real life etc. Its just rods if the stress that is exerted on them is less than the UTS of the material, they "should" never fail and last for an infinate amount of cycles due to certain material properties they are made out of, and rod tend to me designed very conservatively due to the damage they can cause.

    Peoples rod also seem to be breaking when there not even under great load from what I have read from peoples feedback. I think if your really worried about your rods, weather your standard or not, invetsing in thing which could cause them to go, such as proper mapping by people who know what they are doing (such as yourself or an official revo agentcy). Or pay more attention to the things you have listed above. Rods dont just fail, something wasnt right just before they went. I would rather make sure what ever causes the rods to go doesnt happen or is within a safe tollerance on my engine.
    #63
  24. Alex C
    Offline

    Alex C Well-Known Member

    Joined:
    Jan 26, 2010
    Messages:
    2,664
    Likes Received:
    159
    [Jan 25, 2011]
    i would have thought tensile failure would lead to one con rod becoming two, as opposed to it becoming bent and shorter
    #64
  25. Dane
    Offline

    Dane Faster than a V12 Q7

    Joined:
    Nov 11, 2009
    Messages:
    4,005
    Likes Received:
    85
    [Jan 25, 2011]
    Agreed, I had the same thought that, in tension, the rod would start bottle necking (more so) and stretching.
    #65
  26. badger5
    Offline

    badger5 www.badger5.co.uk Site Sponsor

    Joined:
    May 28, 2004
    Messages:
    7,326
    Likes Received:
    694
    [Jan 25, 2011]
    IE website has a good description on their site on rods which is well worth perusing..

    In practical terms, not text book, these are 10 year old cars, 100k mile, multiple previous owners, so your 'as new' design criteria is pretty irrelevant....
    beyond oil starvation and bearing seizure/rod failures the majority are bent from loads/failures from what I see and read.

    you can be lucky, and also unlucky it seems.. and no calculation in the world will make it otherwise
    #66
  27. aragorn
    Offline

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

    Joined:
    Jan 30, 2008
    Messages:
    15,569
    Likes Received:
    313
    [Jan 25, 2011]
    You need to consider that these are mass produced parts, built to a budget.

    The quality and tolerances of each casting will vary greatly, and they will deteriorate over time.

    The rods in the S3 were also not even designed for the S3, nor even the 150hp AEB motor, fitted to the earliest 1.8T's, but they date right back to the NA 4 pot engines fitted to Audi 80's and similar vintage cars making all of 100hp. They are completely unchanged in the 225hp S3 guise, so your already pushing that rod with many times its original specified loads in a standard engine.

    Clearly they were over-specced for their original application, but they're certainly not overspecced for a remapped S3!
    #67
  28. S3 Nattie
    Offline

    S3 Nattie Quattro ist für sissies

    Joined:
    May 19, 2009
    Messages:
    1,600
    Likes Received:
    7
    [Jan 25, 2011]
    Ye they would more likely stretch, so if the rods were snapping or stretching, this would be down to fatigue failure but there not. There bending which is more than likey due to a high compressive downforce. As to the reason why, thats the point. The power loads are offset due to the inertia loads.

    Power (compressive) loads dont tend to break rods "unless" something wasnt right, there not failing due to fatigue. What im saying is instead of replacing them because everyone seems to think they just randomly break, pay more attention to things which can cause excessive power loads which Bill has listed above. Could replace rod and actually not fix the fault, such as the VVT unit. They rarely break due to them just failing. They fail due to low oil pressure
    #68
  29. badger5
    Offline

    badger5 www.badger5.co.uk Site Sponsor

    Joined:
    May 28, 2004
    Messages:
    7,326
    Likes Received:
    694
    [Jan 25, 2011]
    Aragorn:

    do you know this for fact?

    144x20 dimensions remain consistent across many years, but materials also, exact design etc...
    I would be surprised personally..

    I know 144x19 rods although same dimensions, are different construction in early to late 1.8t's

    sintered rods also used now... which would scare the bejesus out of me if modding.. eak!
    Last edited: Jan 25, 2011
    #69
  30. aragorn
    Offline

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

    Joined:
    Jan 30, 2008
    Messages:
    15,569
    Likes Received:
    313
    [Jan 25, 2011]
    The part number goes right back to these early engines, and the part number prefix (027) is not an S3 (or even an A4) engine prefix. I guess its possible they may have revised them, but VAG typically revise the part numbers at the same time and install a supercession against the old number (think of the coil packs, or A4 suspension arms for a good example here), which is not what they've done with the rods.

    Most components on the S3 engine have an 06A prefix, and similarly most parts on the early A4 engines like the AEB have an 058 part number prefix.

    The 19mm rods for instance have an 06A prefix, because they were designed for and first used on that engine.
    #70
  31. superkarl
    Offline

    superkarl MAN OF STEEL

    Joined:
    Mar 28, 2010
    Messages:
    7,614
    Likes Received:
    1,102
    [Jan 25, 2011]
    Good points here with very good reasons as to why it may happen, I don't think anyone is wrong. Trying to look at it from all views. Most logically though is compressive force from increased cylinder pressures.
    It would be good to know the safety factors on this to know how much they can take in terms of a figure of compressive force or whatever, and then know how much and IF (that's an IF) they are being exceeded.

    I believe they could take a certain extent of tuning and still be safe, by having a safe map, and all timing is safe and not too extreme and afr are ok. But how far can forces on the fatigued rods be taken, I guess we'l never know.
    The joys of tuning :)
    #71
  32. aragorn
    Offline

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

    Joined:
    Jan 30, 2008
    Messages:
    15,569
    Likes Received:
    313
    [Jan 25, 2011]
    I guess this is the point. Modern design techniques allow OEM's to build the rod so its JUST big enough to handle the demands of a standard engine.

    As soon as you start tuning, you change that rod from one thats more or less never going to fail, into one that is now a bit of a time bomb.

    Obviously these engines are a bit older, and probably havent had quite the same level of precision when they were originally designed, giving them a bit more flexibility than more modern engines.

    I would imagine, the 19mm rod in the later 1.8T's was designed like this. Someone in the design dept has realised they could use less metal and save money if they fitted this new smaller weaker rod to the lower power engines. The fact they didnt fit it to the 225 model implies that there wasnt enough safety margin in the 19mm rod to handle the 225hp engines output. Presumably at this point it was decided the higher power engines were fine to retain the old 20mm rod, however its interesting to note the FSI rods ARE different from the 225/AEB rods.
    #72
  33. Sandip
    Offline

    Sandip Well-Known Member

    Joined:
    Nov 7, 2006
    Messages:
    2,382
    Likes Received:
    60
    [Jan 25, 2011]
    I've noticed that S3's fitted with the largeport heads tend to make lower torque figures. Seems it's fatigue along with high torque that may cause rods to fail.

    If Audi put the largeport heads on the S3 would this of made this weak part of the engine less vunerable?
    #73
  34. aragorn
    Offline

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

    Joined:
    Jan 30, 2008
    Messages:
    15,569
    Likes Received:
    313
    [Jan 25, 2011]
    Yep, but the point of small port was to help the bottom end tractability, and on the standard engine the torque level isnt a problem.

    What you really want to do is remap the engine without the large boost spike you tend to get. Instead of peaking up at 24psi and then tapering down, a nice flat 18psi across the board would produce a safer, but less torquey engine.
    #74
  35. finesse
    Offline

    finesse Active Member VCDS Map User

    Joined:
    Aug 15, 2006
    Messages:
    2,811
    Likes Received:
    10
    [Jan 25, 2011]
    another point

    replace oil pump :
    #75
  36. beachbuggy
    Offline

    beachbuggy Well-Known Member

    Joined:
    Jan 27, 2010
    Messages:
    1,756
    Likes Received:
    139
    [Jan 26, 2011]

    Good point but not really sure if it's that necessary. As long as you clean the pick up you should be ok, if you're worried about the pump then you can simply remove it, inspect it, clean and refit. They are pretty hardy bits of kit and pretty basic in design going back to the original VW type style of 2 Cogs rotating together, there's very little to go wrong on them and would work happily with out oil and unlikey to seize if it ran dry so even if the pickup got blocked it shouldn't cause any damage to pump mechanism.

    For the sake of 4 bolts to remove and inspect it is worth while doing if you're taking the pick up off.
    #76
  37. <tuffty/>
    Offline

    <tuffty/> Badger 5 Edition Staff Member Moderator

    Joined:
    Sep 14, 2008
    Messages:
    15,898
    Likes Received:
    1,330
    [Jan 26, 2011]
    Oil pick ups are around £15 from a dealer... don't forget a new o-ring while you are at it and use the VAG sump sealant... never had a leaking sump on any VAG I have had the sump off using that stuff...

    <tuffty/>
    #77
  38. finesse
    Offline

    finesse Active Member VCDS Map User

    Joined:
    Aug 15, 2006
    Messages:
    2,811
    Likes Received:
    10
    [Jan 26, 2011]
    #78
  39. aragorn
    Offline

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

    Joined:
    Jan 30, 2008
    Messages:
    15,569
    Likes Received:
    313
    [Jan 26, 2011]
    I beg to differ.

    Our old A4 had oil pressure issues, which started due to the usual sludge issues. I flushed the motor and did regular oil changes, which cleared out all the sludge, but the oil pressure was very low (8psi at hot idle, and barely managing 1bar per 1000rpm when revved). It ran like that for 40k with no real issues other than a very tappety idle, before i replaced the engine, with the engine having covered 195k.

    I stripped the old motor out of intrigue to see if the pickup was blocked, and it was perfectly clear, so the pump itself must have been worn to give the low pressure.
    #79
  40. openside
    Offline

    openside New Member

    Joined:
    Sep 21, 2009
    Messages:
    26
    Likes Received:
    0
    [Jan 28, 2011]
    Phew, scary stuff. I was on the lookout for an S3 and remap it, however after reading this thread i dont think i'll bother. Although i really want one of these cars and have always had vw/audi. Think i might take a trip to the darkside and go for a Ep3 type R or 330ci with less reliability issues!
    #80

Share This Page