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Boost Dumping?

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

  1. Ronniebiggs
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    Ronniebiggs Member

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    Hi everyone

    Just a quick question. I fitted a recirculating forge DV onto my audi 1.8T. Its chipped upto approx 200bhp. It seems to dump to easily. I was thinking that the spring in the DV was to weak. But when I looked on the forge website it gives an example of a chipped audi running approx 225bhp and it recomended the green or at the most the yellow spring?

    "An example of this, would be when using a FMCL007P valve on a 1.8T engine as found in the TT 225hp. The boost pressure on a "chipped" car can peak at 26psi. The recommended spring would be the Green or Yellow"

    Green - 6-8 PSI

    Yellow - 10-12 PSI

    Blue - 14-16 PSI

    Red - 18-20 PSI

    I would imagine that my DV has the green spring. Should I change to a stiffer spring? If so which one?

    I dont have a boost gauge so Im not certain of the boost im running and I have fitted an induction kit and a 4 branch stainless manifold. These are the only modifications I have done.
    If I put my foot down to about 4.5K RPM's and then slowly back my foot off the accelerator the DV dumps and will appear to continue to dump if I keep my foot at that position. Im quite sure the DV is not sticking but is that normal?
    Any advice?

    Thanks
    Andy:think:
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  2. pjmspeedy
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    pjmspeedy Dude, what's mine say ?

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    I would also like to know what spring to use when running at std 163bhp.
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  3. J7USS
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    J7USS Shuddup Foooool!!

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    Ive heard people on here ranting about the standard Bosch 710N valve being the best so I gave it another try (2months old from a standard set up A4) and Took my Forge off for a couple of days.....710N=Crap Valve as Ive always said anyway to the point I put my Forge back on but before I did that I opened it and Im pretty sure I had a green spring and even though its stacks better than the shitty 710N I find it quite weak since ive had the sports CAT so I reckon Im going to try a Blue Spring. Im going to wait till my Boost guage is fitted then see if im right. Mines running around 210bhp - ish!
    Last edited: Aug 15, 2009
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  4. Ronniebiggs
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    Ronniebiggs Member

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    Thanks J7USS, Nice to hear from you again.

    I might just take a gamble and order a spring and see what happens:eyebrows:.

    Let me know if you buy the blue spring and how it goes.

    Thanks
    Andy
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  5. diagnosticator
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    diagnosticator New Member

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    The DV will have the best response with the lightest spring, and installed in the reverse from OE orientation. That is with the inlet at the bottom center port, and the DV discharge at the side port.
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  6. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    J7USS: What did you find "wrong" with the 710N when you compared it with the forge?
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  7. J7USS
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    J7USS Shuddup Foooool!!

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    I found that the Lag was there longer than the Forge, infact the forge is brill when it comes to gear change, no holding back or anything whereas the 2 710N's ive had and tried tend to give me that longer hold on boost.
    Id say my Forge is more or less the same feeling as the HyperBoost I had on the Red one!

    The Lad on my street has a TT and he swapped from the 710N to a Bailey and it was crap yet when he put a Forge on he said it was stacks better.
    Ive never rated the 710N and never will - Guess it works for some and not for all!!!
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  8. aragorn
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    aragorn "Stick a V8 in it!" Staff Member Moderator

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    I see.

    I guess the Bosch valve is doing a more complete dump? whereas the forge must be closing with some pressure still in the inlet?

    Clearly its fitted OE, so i cant see it being bad in terms of it being broken, but perhaps the difference is that the spring in the forge shuts the valve earlier, leaving the inlet slightly pressurised, and therefore the turbo has a bit less work to do after a gearchange?

    Cant really think of any other way a dump valve could improve lag?
    #8

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