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Thread: Which N75??

  1. #1
    JamS3's Avatar
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    Which N75??

    I'm wanting a bit extra torque on the road which will be noticable. I'm running a AMD remap which on their rollers registered 269bhp and 262lbs of torque.

    Which N75 will be best to go for to get a little bit extra, I heard the W version would be best as some others make the car hit limp mode.

    Any advice?

    Cheers

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  3. #2
    JamS3's Avatar
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    Re: Which N75??

    Anyone????

    Oh and I think I meant the H version was the one to go for as it was a bit more aggressive than the J version, however don't want to hit limp mode!

    Any advice?

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    Re: Which N75??

    Forget n75's is my advice.

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    Re: Which N75??

    Why would you say that Ryan?

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    Re: Which N75??

    what are you trying to achieve by having a different n75?
    Get your requested boost altered properly with mapping.

  7. #6
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    Re: Which N75??

    Just a little extra torque of around 20lbs/ft which the H valve has been mentioned to get by delivering the boost a bit more aggressive.

    Iv'e gone the remap route and don't want to spend more money getting another one done.

    Just thought it would be a decent cheap extra mod to "polish" things off if the valve gets me a bit extra....

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    Re: Which N75??

    You shouldn't run a n75 over 95% duty and a good mapper should have done this on your remap. Requested should be alot higher than actual until peak boost. I take it your trying to get a bit of overboost.

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    Re: Which N75??

    No just a bit more than I have at the min...

    Would a H version do this without any problems on the car?

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    Re: Which N75??

    a n75 is a n75 ,putting on one that is not responding aswell as a stock unit is a bit of a bodge hence why you get limp mode.

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    Re: Which N75??

    Personally think it's a waste of time and money.What exactly makes it a "race" valve?Just the fact that it's slow to respond and overboosts.

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    Re: Which N75??

    It's not meant for a 1.8t,hence it's slow to respond ,actual is higher than requested until it catches up.

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    Re: Which N75??

    If you want more boost,map sensor max is 2540mbar or 1.54bar boost,change this for a 3bar diesel map sensor and get it remapped for actual peak boost,ie up to 2 bar if the k04 lasts that long!

  14. #13
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    Re: Which N75??

    ECS valve is in fact a N75 H valve but is prone to producing boost spikes In some setups I would say the J Valve is a much safer option.

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    Re: Which N75??

    [ QUOTE ]
    Personally think it's a waste of time and money.What exactly makes it a "race" valve?Just the fact that it's slow to respond and overboosts.

    [/ QUOTE ]

    Basically...yeah...and the fact that the Americans love to call things 'race' when they are plainly no such thing!

    The H valve works though...if you can avoid limp mode.

    Although I noticed next to no difference between an H and a J valve and what they did to my S3.
    Both produced silly boost levels...but I think the H's delivery was more savage.

  16. #15
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    Re: Which N75??

    [ QUOTE ]
    ECS valve is in fact a N75 H valve but is prone to producing boost spikes In some setups I would say the J Valve is a much safer option.

    [/ QUOTE ]

    On my car...not any safer.
    It produced only fractionally less boost...both lit limp ocassionally.

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    Re: Which N75??

    [ QUOTE ]
    If you want more boost,map sensor max is 2540mbar or 1.54bar boost,change this for a 3bar diesel map sensor and get it remapped for actual peak boost,ie up to 2 bar if the k04 lasts that long!

    [/ QUOTE ]

    Don't be synical Ryan...

    My K04 was producing 1.8+ bar for long enough...occasionally as high as 1.9 bar peak...and it's still fine.

    You just can't produce the boost top end due to it's size...


    You can run with a saturated MAP sensor as long as you are sure your fuelling is OK and you aren't running lean...mine was OK.
    But you'll need something to avoid satrurating the MAP sensor or you'll hit limp...I'd suggest some form of adjustable electronic MAP clamp might work... [img]/ubbthreads/images/graemlins/tongue.gif[/img]

  18. #17
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    Re: Which N75??

    Leave the poor ickle k04 alone.

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    Re: Which N75??

    [ QUOTE ]
    Leave the poor ickle k04 alone.

    [/ QUOTE ]

    I have!!

    I didn't like the power delivery with the alternative N75 in...so I chose to run standard as it was more drivable.

    Still at 1.65-1.70 bar peak though...


    One more thing:
    I hope people realise that the inlet temperatured are pretty much exponential...a small increase in boost gives a big hike in inlet charge temperature...I would NOT have run a chipped S3 + different N75 on standard ICs!!

    Even with my uber cooling IC set-up, the temperature increase was obvious.

  20. #19
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    Re: Which N75??

    Or diesel map sensor,properly mapped as i suggested.

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    Re: Which N75??

    [ QUOTE ]
    Or diesel map sensor,properly mapped as i suggested.

    [/ QUOTE ]

    There weren't too many doing custom (proper custom) maps when mine was done...and even less within 400 miles of me!

    A MAP clamp may have been easier...

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    Re: Which N75??

    Thats because your running the turbo so far out of it's effiency it's a pure flame thrower,i have seen dynos of cars just dropping power like mad every run.

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    Re: Which N75??

    Personally for most guys a standard 1.5 peak map would be fine. You pushed the limits Glen but perhaps a change of turbo like these eliminators with decent intercooling would be a better option.

  24. #23
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    Re: Which N75??

    [ QUOTE ]
    Thats because your running the turbo so far out of it's effiency it's a pure flame thrower,i have seen dynos of cars just dropping power like mad every run.

    [/ QUOTE ]

    The alternative N75s were also dynod in standard and 'normal' chipped 95 octane maps...
    The gains in temperature are quite large...much more so than people think...so the ECU cuts the timing back.
    Although the car produces more peak boost and feels really quick...it's loss of timing advance at the top end negate the increase in boost....
    So the car feels a lot faster (and at peak torque does make a lot more boost) it heatsoak's badly - and quickly - and isn't much faster point to point.

    It's a bodge...as you have said.

    And not a bodge to be done lightly..

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    Re: Which N75??

    [ QUOTE ]
    Personally for most guys a standard 1.5 peak map would be fine. You pushed the limits Glen but perhaps a change of turbo like these eliminators with decent intercooling would be a better option.

    [/ QUOTE ]

    I tested at 1.4 bar...and it was getting hot.

    In fact, I was seeing 78 degrees at the inlet manifold (on the dyno) with approx 1.45 bar...on standard ICs.
    Too hot for me...

    At 1.89 bar on the dyno, on uprated ICs...24-28 degrees. Big difference...



    EDIT:
    I'm sure most will be just fine...but people need to be aware of what the addiotional boost does...and the problems it can cause.

    The 1.8T will take massive boost...but not massive temperatures!!

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    Re: Which N75??

    Would have been interesting to see how much timing was being pulled,did you log it with vag-com?

    As a comparison i hardly ever see more than 25 degrees intakes and thats with running 1.5bar held with repeated runs.
    More efficient turbo/huge intercooler/water injection(yes it does work!)

  27. #26
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    Re: Which N75??

    What IC's were you running? Not a single front mount but a pair of uprated IC's?

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    Re: Which N75??

    [ QUOTE ]
    Would have been interesting to see how much timing was being pulled,did you log it with vag-com?


    [/ QUOTE ]

    I did...but I'll be damned if I can find it...
    7+ degrees seems to ring a bell...but may be wrong.


    [ QUOTE ]

    As a comparison i hardly ever see more than 25 degrees intakes and thats with running 1.5bar held with repeated runs.


    [/ QUOTE ]

    I can well believe it...


    [ QUOTE ]

    More efficient turbo/huge intercooler/water injection(yes it does work!)

    [/ QUOTE ]

    All of which reduce the temperature...

  29. #28
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    Re: Which N75??

    [ QUOTE ]
    What IC's were you running? Not a single front mount but a pair of uprated IC's?

    [/ QUOTE ]

    A bespoke SMIC based on a Forge Golf 4 unit but with S3 pipes on it...and a bespoke Star Performance designed and Forge built FMIC.

    Running them in series...drivers side SMIC, then FMIC.

  30. #29
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    Re: Which N75??

    Yep, i also ran the same set-up minus the uprated side mount.Did cool the charge ok but with a bigger turbo there was problems with pressure drop which i seem to remember telling glen about a few years back.K04 doesn't shift enough air to cause a problem.

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    Re: Which N75??

    [ QUOTE ]
    Yep, i also ran the same set-up minus the uprated side mount.Did cool the charge ok but with a bigger turbo there was problems with pressure drop which i seem to remember telling glen about a few years back.K04 doesn't shift enough air to cause a problem.

    [/ QUOTE ]

    I remember vaguely...there was a pressure drop with my set up too...but as you say, worse for your set-up.

  32. #31
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    Re: Which N75??

    The intercooler core is key,make sure it's a good one and not off a diesel van or something.Also there is major fitment issues getting a decent sized one behind the stock bumper but thats a different story.Mine has 1psi pressure drop now tested at 1.6bar boost.Previously was near 6psi at same boost level.

  33. #32
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    Re: Which N75??

    What would you think of this Modshack boost machine?

    http://www.modshack.info/bm.htm

    Im now peaking about 1.35 bar with MTM chip and fuel/air ratio is on the rich side. So i think that there is possibility to gain boost a little bit. My car has also FMIC, so intake temps are quite reasonable.

    Ive read a good review about that BT at Audiworld forum.
    http://forums.audiworld.com/tt/msgs/1307431.phtml

  34. #33
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    Re: Which N75??

    Trawling through the search facility alot of people seem to be running the J valve with a chipped car with no problems.

    Does anyone know of any associated problems with a different N75 on a chipped car?

    Think I'm going to do this mod but don't want to be kicking myself in a few months time when Iv'e got problems with the motor!

    Iv'e got a boost gauge fitted now and in the low gears I'm spiking at about 16-17psi. In 4th and 5th it goes to about 19 or 20psi sometimes, I suppose I could keep a eye on things this way?

  35. #34
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    Re: Which N75??

    When I said associated problems I meant peoples own experiences with their own or mates cars.

    I appreciate all the advice comments above!

  36. #35
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    Re: Which N75??

    [ QUOTE ]
    Trawling through the search facility alot of people seem to be running the J valve with a chipped car with no problems.


    [/ QUOTE ]

    I believe so too...just remember that it's not a free mod. There are some downsides...
    But as long as people know this, use decent pertol and watch out for limp mode...or understand the fact that if it's stinking hot they will 'enjoy' the ECU potentially cutting the timing back, there should be no issues.


    [ QUOTE ]

    Think I'm going to do this mod but don't want to be kicking myself in a few months time when Iv'e got problems with the motor!


    [/ QUOTE ]

    I don't think you'll have problems...if you hit limp mode, remove it.
    If the inlet charge gets too hot, the ECU will protect the engine.

    Just be aware of what you are doing...and you'll be fine.


    [ QUOTE ]

    Iv'e got a boost gauge fitted now and in the low gears I'm spiking at about 16-17psi. In 4th and 5th it goes to about 19 or 20psi sometimes, I suppose I could keep a eye on things this way?

    [/ QUOTE ]

    A good idea...but you need a wide band lambda or a run on a RR logging a/f ratio with a wide band lambda to ensure you're not running rich.
    I wouldn't go doing any flat out top-speed runs without first verifying that you aren't running lean with an alternative N75 fitted...but that's just me.

    You pays your money, and makes your choice.

 

 

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