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Power loss @ wheels massive on Quattro!

Discussion in 'A3/S3 Forum (8L Chassis)' started by dans3, Jul 5, 2003.

  1. dans3
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    dans3 Member

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    I was absolutely amazed at the high power loss at the wheels on a S3 (I'm presuming the same for all you 4wd A3's). I've recently had my S3 remapped at AMD and got a pretty impressive increase and good power at the flywheel. I was shocked to then see Drills bhp at the wheels of his FWD A3 compared to that of my S3, it wasn't much less!

    Power at Flywheel: 260.5bhp /ubbthreads/images/graemlins/smile.gif
    Power at wheels: 177bhp!! /ubbthreads/images/graemlins/crazy.gif

    I'm presuming this is due to Haldex???

    Nevertheless, still VERY happy!
    #1
  2. scoTTy
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    scoTTy Active Member

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    I've seen this before but it's not as bad as you think.

    When the cars's on rollers the rears have to have power transferred to them to make them rotate.

    On a normal road they are normally rolling at the same speed as the front hence the Haldex is disengaged.


    In other words when in two wheel drive mode - straight lines - you'll not "waste" all that power. When fronts and rears are rotating differently - traffic light GP's, "sporting driving", etc then admittedly you are subject ot these extra transmission losses.

    Therefore the figures you have posted should be worst case. I suppose you could always do a rollign road with the handbrake on one notch so that the rears are disengaged. I wouldn't recommend the other method which involves removing the Haldex fuse as I believe this has caused some people issues.
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  3. AL_B
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    AL_B Active Member

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    Scotty a couple of questions...

    [ QUOTE ]
    scoTTy said:
    When the cars's on rollers the rears have to have power transferred to them to make them rotate.

    [/ QUOTE ]
    Stupid question: I take it you do mean the car transferring power to them. i.e. not some fancy mechanism built into the rolling road? /ubbthreads/images/graemlins/smile.gif

    [ QUOTE ]
    scoTTy said:
    On a normal road they are normally rolling at the same speed as the front hence the Haldex is disengaged.

    [/ QUOTE ]
    On a rolling road, is the car not "traveling" in a straight line? /ubbthreads/images/graemlins/wink.gif And won't the haldex be shifting power about as it deems fit?

    IMO, the way the Haldex works, when it comes into play, when its not working, is still a grey area, or me anyway.

    [ QUOTE ]
    scoTTy said:
    In other words when in two wheel drive mode - straight lines - you'll not "waste" all that power.

    [/ QUOTE ]
    Under light throttle I presume? But surely under full throttle Haldex will be engaged? Maybe not I guess if the front wheels aren't slipping. Hell I don't know, thats why I'm asking. /ubbthreads/images/graemlins/smile.gif

    Cheers

    AL
    #3
  4. Drill
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    Drill Member

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    [ QUOTE ]
    dans3 said:
    I was absolutely amazed at the high power loss at the wheels on a S3 (I'm presuming the same for all you 4wd A3's). I've recently had my S3 remapped at AMD and got a pretty impressive increase and good power at the flywheel. I was shocked to then see Drills bhp at the wheels of his FWD A3 compared to that of my S3, it wasn't much less!

    Power at Flywheel: 260.5bhp /ubbthreads/images/graemlins/smile.gif
    Power at wheels: 177bhp!! /ubbthreads/images/graemlins/crazy.gif

    I'm presuming this is due to Haldex???

    Nevertheless, still VERY happy!

    [/ QUOTE ]
    Hate to break it to ya dude, but my A3 IS a Quattro /ubbthreads/images/graemlins/crazy.gif But the Oettinger tech disabled the Haldex for the Dyno run. Although the situation didn't permit my asking HOW it was disabled, I would presume via pulling the fuse, but am unsure.

    /ubbthreads/images/graemlins/beerchug.gif
    #4
  5. Mo-S3
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    Mo-S3 Member

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    Ive heard of stories through thegrapevine that if u pull the fuse on the haldex that u can knacker it, Is this absolutly true??
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  6. Drill
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    Drill Member

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    I think it can overheat the Haldex unit when used for a while as such, but I'm unsure. /ubbthreads/images/graemlins/confused.gif

    /ubbthreads/images/graemlins/beerchug.gif
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  7. audi_girl
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    audi_girl Active Member

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    Didn't someone blow their S3 up that way??

    Drill (no offence here to you or Oettinger) but what's the point of a dyno reading with the Haldex disabled? You don't drive it like that, so wouldn't you want the reading with the quattro etc., how you have it on the road?
    #7
  8. Drill
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    Drill Member

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    Well, the wheel bhp reading would be the only one "off", all the engine data is the same, therefore I wasn't worried about it /ubbthreads/images/graemlins/grin.gif I plan on going back when I get the exhaust and turbo Intake pipe (No idea when /ubbthreads/images/graemlins/smile_smoking.gif) but THEN I'm gonna make sure they do a full 4-wheel plot as well /ubbthreads/images/graemlins/grin.gif

    /ubbthreads/images/graemlins/beerchug.gif
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  9. dans3
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    dans3 Member

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    [ QUOTE ]
    Gambba said:
    Which ever way you look at this it's very good news for us FWD A3's taking on A3 Quattro's and S3's (In the dry), due to less power loss through the drive line.


    [/ QUOTE ]

    It's all about controlled power (traction). Don't get over confident all you FWD owners!! /ubbthreads/images/graemlins/devil.gif
    #9
  10. AL_B
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    AL_B Active Member

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    ScoTTy, forgot to thankyou for your reply. Cheers.

    Think your point [3] may be slightly wrong though, or half right depends how you look at it. /ubbthreads/images/graemlins/smile.gif Namely, under a constant speed, say on a motorway, the Haldex is probably transferring between 10-15% of torque all the time. If you put your foot down, it can transfer more, due to differences in rolling radius of the tyres, due to weight transfer. If I understand this post (below) correctly.

    We've just had some excellent info through from Haldex themselves....

    Haldex and Torsen

    Regards

    AL
    #10
  11. edwin98
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    edwin98 Member

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    You fwd guys, maybe you think that we lose many power, and maybe it is.

    but my car is doing 0-100 km 5.6 sec. Wich fwd audi does the same?

    never trying timing 100-200 km, but i think the difference will only be bigger.

    Of course you loose extra power in the drive train, but it isn't as much as you think (i think?)

    /ubbthreads/images/graemlins/smirk.gif
    #11

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