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Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by CMD, Oct 15, 2009.

  1. CMD
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    CMD Pointing Forward's!!!!!!!!!

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    [Oct 15, 2009]
    Hi i'm now looking at buying the N75 valve and a Re-Cecirculating dv for my 1.8t 190.
    A few question's. Awsome GTi sell the n75 type valve, or should i buy the 'J' type from Audi dealer. Does any one have a part number ??
    Also what would be the best re-cecirculating dv. Is there any i should avoid .
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  3. J7USS
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    J7USS Shuddup Foooool!!

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    [Oct 15, 2009]
    Id recommend a 'Hyperboost valve' or a 'Forge 007' valve. Both have had positive effects on my motors.
    The N75J valve is for some reason a little vicious on my blue one, hit limp mode once whereas on my red one I never ever had limp mode but saying that, this blue one has a few more upgrades for power hence why I reckon the reason for Limp!
    Part number is : 034906283J

    Im not 100% sure but the Awesome one that they do is the H valve (again, im only saying what ive been told by some of the buyers) and I was looking into the H valve but have heard some scary stories about this one, its way too aggressive for some, perfect for some, Rubbish for some. Its trail and error I guess. You can always buy both, try them and the one you dont want, Ebay it and you'll defo get rid and you'll get your money back.

    ...but id recommend the Forge007 DV & the N75J valve. :icon_thumright:
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  4. CMD
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    CMD Pointing Forward's!!!!!!!!!

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    [Oct 15, 2009]
    Nice on J7USS i will shift down to Audi on Sat with Part number : 034906283J..
    Any idea of price
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  5. J7USS
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    J7USS Shuddup Foooool!!

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    [Oct 15, 2009]
    No probs. They are about £53 with the VAT IIRC...:think:....or you could double check with 'PJM Speedy' - he can supply you one!
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  6. CMD
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    CMD Pointing Forward's!!!!!!!!!

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    [Oct 15, 2009]
    Great stuff ...I'm ready to go back to the dealer last time i spoke to them about a few thing's one being four wheel tracking. They looked at the car in the car park and said no chance, due to the wheels and coilovers what a load of S..T i said to the guy. I was asked to leave.
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  7. S4twiggy
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    S4twiggy Fully Certified Detailer!!

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    [Oct 16, 2009]
    wot different types of N75 are there then?? wot exactly do they do?

    im looking t change to forge 007 for my S4 but at nearly £100 a pop and i need 2 ill have to save up for them lol
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  8. J7USS
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    J7USS Shuddup Foooool!!

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    [Oct 16, 2009]
    Here goes then, a little research and experience by myself. Apologies for the essay :)...(instead of me writing it all over again, Ive stole it off the guy...:eyebrows: with his few pence worth added too)
    ...the wastegate is operated by the turbo itself. The boost the turbo produces is directly fed to its own wastegate. What does this mean? When the turbo spools up, it will create boost and this boost will open its own wastegate, shutting itself automatically down.
    But where's boost control? And wheres ECU?

    Here comes the N75 valve. The N75 valve is inserted between the turbo's high pressure output and the wastegate. If the turbo would directly linked to the wastegate, it would not be able to produce lets say more than 0.3-0.4 bar of boost, because it would shut itself down immediately. When the ECU wants more boost (because you are stepping on it for example), it vents some air from this loop (turbo--->wastegate) so the wastegate will not open at all, or will open later.

    The N75 has got 1 boost input, and 2 outputs. At the input, boost is entering into the N75 and exits on one of the outputs going to the wastegate. When N75 is closed (default state), all the boost goes to the wastegate. When ECU opens the N75 valve (because it has got an electrical plug too coming from ECU), so when ECU opens it, some of this boost (which would operate the wastegate) is leaving/leaking back to the inlet (and not opening wastegate). Since the N75 valve has NO state in between, it is opened or closed.
    The ECU switches it ON/OFF all the time (several times a second) to generate the desired amount of boost. Doesn't it reminds you to something???? ... Yeah, it's surging. But it is absolutely normal, this is how ECU controls the wastegate. When a car is chipped, the boost is a LOT higher than it is designed to operate on, so this kind of boost control will be noticable.
    By adjusting the N75 valve, you can adjust the amount of air which should leave when the N75 is opened. If you adjust the N75 to the right, you will "close" the N75 valve, so just a few amounts of air is vented from the wastegate which will result in a lot smoother drive (eliminating surging, because the boost will be more constant), BUT at the same time it will introduce more boost to the wastegate, causing LESS overall boost. Adjusting the N75 valve to the left will "open" it, enabling more air to escape from the wastegate when N75 is opened, which will result in more boost (because wastegate wont open), BUT at the same time it MAY cause surging as the N75 opening/closing will be more obvious.

    S4 Twiggy - just advice mate, if you do uprate your DV's then defo dont go with Baileys as the few I know who had baileys went back to the 710N DV's as the baileys were pretty ***** for them. Dont know why, just repeating what ive heard from a few S4 owners!!!:icon_thumright:
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