Page 2 of 3 FirstFirst 123 LastLast
Results 19 to 36 of 51

Thread: Hopping on the O1E bandwagon

  1. #19
    Registered User
    Join Date
    Mar 2007
    Location
    Evil Empire
    Posts
    448
    You can't adjust the opening pressure, it's regulated by the spring stiffness, regardless of how much you tighten them up. Spring ratio is linear & it's the spring ultimately "deciding" when to open the flapper in "boost-off" operation.

    It would appear to make a difference when you do a mityvac test (since the volume of air is so tiny), but it's wrong. If overtightened - you're essentially just restricting the arm motion (thus, opening time & max flow through the flapper if it can't open completely anymore).

  2. #20
    Registered User
    Join Date
    Oct 2018
    Location
    MN
    Posts
    40
    Quote Originally Posted by nubcake View Post
    You can't adjust the opening pressure, it's regulated by the spring stiffness, regardless of how much you tighten them up. Spring ratio is linear & it's the spring ultimately "deciding" when to open the flapper in "boost-off" operation.
    The opening pressure would be regulated by the spring PRELOAD, not the stiffness. Once the wastegate is closed, any additional tightening of the adjustment rod is going to increase the PRELOAD of the spring effectively changing the opening pressure.


    Quote Originally Posted by nubcake View Post
    It would appear to make a difference when you do a mityvac test (since the volume of air is so tiny), but it's wrong. If overtightened - you're essentially just restricting the arm motion (thus, opening time & max flow through the flapper if it can't open completely anymore).
    You are right here though and this is where the spring rate comes into play. The more you increase the preload of the spring the more you're also increasing the amount of pressure in the actuator required to open the wastegate fully.

  3. #21
    Registered User
    Join Date
    Mar 2007
    Location
    Evil Empire
    Posts
    448
    Again: spring rate is linear. You do not change it by preloading.
    I'm not going to argue, you're welcome to listen to the info or keep thinking otherwise.

    EDIT:
    If you want to test it - don't use a mityvac. Take an air compressor with good flow & a precise pressure regulator.
    You'll see, that preload doesn't change the cracking pressure. It'll always be ~0.35 bars with RS6 turbos.
    Last edited by nubcake; April 2nd, 2021 at 15:48.

  4. #22
    Registered User
    Join Date
    Oct 2018
    Location
    MN
    Posts
    40
    Yes, spring rate is linear, but the point at which the wastegate opens is determine by the spring preload set by the adjustment nut

    Here's a diagram of the system with the actuator on the left and the wastegate arms on the right.


    The amount of force that the spring puts out is Fs=kx where k is the rate and x is the amount of compression. This is where the linear spring rate lives. The spring force is pushing left on the diagram above. Pushing right to open the wastegate is the force of the pressure inside the actuator Fp=PA where P is the pressure and A is the surface area of the piston.

    If Fs is greater than Fp, the wastegate will be closed since Fs is pushing left in the diagram above and holding the flap against the housing. The cracking pressure of the wastegate is when Fs = Fp or kx = PA.

    Since k and A are constants we can see that the spring preload (x) affects the cracking pressure (P).

    So nubcake, your way of setting the wastegates works because you set the preload of the springs equally between the two sides by turning the nut around twice. I'm going to go the other route of determining the cracking pressure from one side (since I don't know how many turns of the nut they went at the factory) and adjust the preload of the spring on the other side until the cracking pressures are equal.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	wastegate diagram.jpg 
Views:	128 
Size:	38.9 KB 
ID:	19408  

  5. #23
    Registered User
    Join Date
    Mar 2007
    Location
    Evil Empire
    Posts
    448
    Thanks for taking the time to explain.
    What you describe there seems to make sense, but it doesn't really jive with the real world logs for some reason.
    Possibly, the pressure change is very minimal, unless you really overtighten it.
    I'll need to ponder this for a while.

    Sorry for my tone, I was wrong.

  6. #24
    Registered User
    Join Date
    Oct 2018
    Location
    MN
    Posts
    40
    No worries. It could be very possible that the spring is already preloaded in the actuator and any ADDITIONAL preload that is added by the rod is minimal which would match what you see in the real world.

    For example, it feels like it's maybe preloaded around 5lbs and if we assume the spring has a 1lb/in rate then moving the nut two turns only compresses the spring an additional 2mm or .080" which means we only add another .08lbs on top of the 5lb of preload in the actuator which is pretty negligible. I'll try to get some force and spring rate data, but I'm now leaning towards it doesn't make any difference like you said

  7. #25
    Registered User
    Join Date
    Feb 2011
    Posts
    68
    Quote Originally Posted by NerdyDeeds View Post
    Since the passenger side wastegate didn't get disturbed I'm inclined to use the mityvac to find the cracking pressure then adjust the drivers side to match. They should open at the same pressure right?

    I'm picking up a gearbox this weekend. I'm going to chance it on it being a good used box and spend the money on injectors and fuel pump for E85 conversion.
    You can do that, or even better, you can get a T-fitting and do both at the same time, for guaranteed synchronization.

  8. #26
    Registered User
    Join Date
    Apr 2019
    Location
    Annapolis, MD
    Posts
    261
    Quote Originally Posted by jibberjive View Post
    You can do that, or even better, you can get a T-fitting and do both at the same time, for guaranteed synchronization.
    So I did a little fiddling this morning....Set up a quick T fitting and used my brake power bleeder which gives pretty accurate low pressure readings since it has the reservoir tank to pump up by hand, rather than just pressurizing with a compressor....each hand pump on the power bleeder is less than .1 psi, giving pretty good control over pressure.

    When I re-set my wastegate actuators, I did the closed plus two turns of a nut to snug them up. This made it so you can still spin the flappers if you try, but can't get any tighter with more turns of the nut due to the springs. What I found was the flappers would just start to crack at about 3.7-3.8 psi, just enough so I could spin them with equal resistance with my fingers...did a pump at a time for just a hair more psi, and followed the resistance so they would match. I did make about a 1/5 to 1/4 turn on one nut to get them to match up, but the initial setting was pretty spot-on. Looks like they really open up from 4.3-4.5 psi. Purged and re-started a few times to compare, and results came out the same. So, it was definitely helpful to T this up to do them with absolutely identical pressure since the tolerance is too close to measure with most gauges...probably being .1-.3 PSI variance if you don't test as a pair.




  9. #27
    Registered User
    Join Date
    Oct 2018
    Location
    MN
    Posts
    40
    Nice! I didn't get a chance to play with the force gauge this weekend, but it's still on my to do list. I'll definitely tee the two together when I do the final adjustments though. What happens, or what do you feel in the car, if the wastegates aren't sync'd or opening when they're supposed to?

  10. #28
    Registered User
    Join Date
    Oct 2018
    Location
    MN
    Posts
    40
    I made some progress on a couple of the mini-projects, but haven't really completed any of them yet.

    First was to remove the spacer on the back of the crank shaft. Drilled out and tapped a 7/8" hole then threaded a bolt in to push the spacer out. It worked really well except I went a little further than I meant to with the drill.



    Once that was out I wanted to replace the rear main seal since there was just a whiff of oil on the seal. Got the plate off and now waiting for the gasket.

    A bonus project is now a water pump replacement (done 7000 miles ago) since there's coolant leaking from the freeze plug :


    Bigger injectors for E85 are in. I went with the Bosch/Porsche 630cc units. I noticed some insulation and other signs of old mouse activity under the intake manifold. I was going to leave it since it doesn't seem to be causing any problems, but then the knock sensor plug (green plug next to the injectors) decided to completely dissolve while I unplugged it so the manifold is coming off to replace it.




    I also have the camshafts out and the shoes replaced on the tensioner so that can go back together this week. I picked up the new(old) transmission locally which is most likely in need of a rebuild. I'm going to pull it apart and check but I'm 99% it's getting new parts. I'm thinking/hoping just the 1-2 shift collar and syncros from JHM should be enough. Otherwise the full rebuild kit isn't too much more. I do need to find a shifter box as well if anyone has one laying around they don't need let me know.

    There was also plenty of [s]forbidden espresso[/s]gunk built up in the PCV hoses. I'm thinking this may have been why I was getting so much oil in the drivers side charge piping.

  11. #29
    Registered User
    Join Date
    Mar 2007
    Location
    Evil Empire
    Posts
    448
    Quote Originally Posted by NerdyDeeds View Post
    What happens, or what do you feel in the car, if the wastegates aren't sync'd or opening when they're supposed to?
    One's too loose - you're not getting the boost you should be.
    One's too tight - car feels very strong, but one turbo is always working too hard. You might occasionally throw an overboost DTC.

  12. #30
    Registered User RS8's Avatar
    Join Date
    Jul 2012
    Location
    Sweden
    Posts
    240
    Why did you buy so small injectors when you are going to use E85 ?
    630cc will only work for about 500 -550 crank hp on E85 and 3bar fuel pressure.

    I have driven on 1000cc EV14 with E85 with RS6 ECU and air mass meter and it worked great with correct tune and 600hp+

    but now I have changed to 1500cc but then without air mass meter and instead MaxxEcu Pro that controls everything.
    Last edited by RS8; April 6th, 2021 at 10:02.
    RS6 engine, 6spd tdi 01E, upgraded RS6 turbos, custom built exhaust manifolds, A8 intake camshafts, wagners ic's, bigger fuel rails, AN8 fuel line, walbro 450lph fuel pump
    and EV14 1000cc/95lb fuel injectors in my S8/RS8

  13. #31
    Registered User
    Join Date
    Mar 2007
    Location
    Evil Empire
    Posts
    448
    630s are fine for stock turbos & stock 4 bar FPR.
    Which is also in the ballpark of power figures you quoted.

    1500cc are way overkill, unless you're aiming for like 1k+++ chp.
    1000cc are a good choice & readily available, but they need some mods to fit.

  14. #32
    Registered User RS8's Avatar
    Join Date
    Jul 2012
    Location
    Sweden
    Posts
    240
    But you can buy different EV14 with adapters in top or bottom so it fits and there is several to choose on between 700-957cc

    What I can read these 630cc flow this:
    3 bar: 612cc / min
    4 bar: 708cc / min

    With 4bar
    BSFC at 0.85 = for turbo and E85
    Duty cycle 0.85
    Then 708cc will work for 540 crank hp
    With BSFC at 0.75 it will work to 600hp

    I have seen a stock RS6 engine in a Ultima kit car so it had free flow air filters etc, this made over 600hp on E85 on stock Rs6 turbo's


    And the big problem is when NerdyDeeds want more than 550hp then he must buy 8pcs new injectors again..
    So better to buy "to big" now then have to change later.
    RS6 engine, 6spd tdi 01E, upgraded RS6 turbos, custom built exhaust manifolds, A8 intake camshafts, wagners ic's, bigger fuel rails, AN8 fuel line, walbro 450lph fuel pump
    and EV14 1000cc/95lb fuel injectors in my S8/RS8

  15. #33
    Registered User
    Join Date
    Mar 2007
    Location
    Evil Empire
    Posts
    448
    Your calculations are both correct & wrong at the same time.
    Bottom line is these injectors are more than enough for stock rs6 turbos & E85.

  16. #34
    Registered User
    Join Date
    Oct 2018
    Location
    MN
    Posts
    40
    @RS8 I'm not planning on chasing HP with this car and the 630s are recommended from various people. I am going with a 5 bar regulator while I'm in there since that's pretty easy and inexpensive.

    I was pretty satisfied with the stock power. The reasons I'm going to E85 are that it's easy to find in the midwest, I don't have to worry about the transmission anymore, and since I'm already having a tune done because of the swap I might as well have it tuned for E85 instead of paying for another tune later.

  17. #35
    Registered User
    Join Date
    Mar 2007
    Location
    Evil Empire
    Posts
    448
    I'd stay away from 5 bar FPR. Putting unnecessary strain on fuel pumps.
    If anything, a 3.8 bar from Porsche 997tt is a much better option (it has a bigger return internally, which might behave properly with bigger fuel pumps).

  18. #36
    Registered User RS8's Avatar
    Join Date
    Jul 2012
    Location
    Sweden
    Posts
    240
    Quote Originally Posted by nubcake View Post
    Your calculations are both correct & wrong at the same time.
    Bottom line is these injectors are more than enough for stock rs6 turbos & E85.
    I'm using a injector calculator, and what I found out myself is to always go bigger than you think will work.

    These are just kind tips from me so he do not have to buy new ones again in a year or so.
    RS6 engine, 6spd tdi 01E, upgraded RS6 turbos, custom built exhaust manifolds, A8 intake camshafts, wagners ic's, bigger fuel rails, AN8 fuel line, walbro 450lph fuel pump
    and EV14 1000cc/95lb fuel injectors in my S8/RS8

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •