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Thread: WUR connections....

  1. #1
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    WUR connections....

    hey... i am in the midst of turbo build, and have this WUR here



    Hmmm.. look at that theres cofee on the table there
    ANYHOW...... my question is what goes on the three ports... i know one is boost, but which one?... one is atmo, right? and the other?

    Josh.... i know you know this one... i'll be waitin....

    Thanks in advance everyone!!
    -tristan

  2. #2
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    Yep - Josh will know for certain..
    Btw: coffee is not good for you .

    My '78 does not have all those vacuum lines, yours is a newer model WUR?
    Tbd

  3. #3
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    no this is a WUR from an audi that came with a turbo... i also have a volvo 240t FD/AFM which will be going on when i make the bracket for it tomorrow or next week

    and hey! coffee is so, so good for you! I wouldn't be alive without it...... mmmm i reeaalllly love coffee.... almost as much as i love my bimmer, maybe more... coffee is considerably cheaper
    Last edited by greenmachine78; 01-20-2010 at 07:41 PM. Reason: Automerged Doublepost

  4. #4
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    Quote Originally Posted by greenmachine78 View Post
    no this is a WUR from an audi that came with a turbo... i also have a volvo 240t FD/AFM which will be going on when i make the bracket for it tomorrow or next week

    and hey! coffee is so, so good for you! I wouldn't be alive without it...... mmmm i reeaalllly love coffee.... almost as much as i love my bimmer, maybe more... coffee is considerably cheaper
    Oh my.. definately Josh's territory here. And when you start spilling coffee - that's a sign that caffiene is not good for you, also caffiene abuse .
    Tbd

  5. #5
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    Quote Originally Posted by greenmachine78 View Post
    no this is a WUR from an audi that came with a turbo... i also have a volvo 240t FD/AFM which will be going on when i make the bracket for it tomorrow or next week
    Why do you need a bracket? The FD should fit on the AFM just fine, and that should mount on the stock lower AFM without any modification.


    As far as the WUR goes: The one on the top vents to atmosphere. The other two both go to a vacuum source on the manifold, but the bottom one needs a check valve, set up in this fashion:



  6. #6
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    THanks drew, on the check valve, should it be holding vacuum, or boost, by your pic it looks like it shoud hold vacuum, but i don't want to assume and be wrong.

    the bracket is to mount the volvo AFM/FD unit to the side of the engine bay, as i will not be using the stock airbox, but rather a short curved tube and cone filter.... the idea of mounting on the other side of the engine has been tossed around too, as that would place it closer to the turbo, therfore greater throttle response
    Last edited by greenmachine78; 01-21-2010 at 12:45 AM. Reason: had more to say

  7. #7
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    Quote Originally Posted by greenmachine78 View Post
    the bracket is to mount the volvo AFM/FD unit to the side of the engine bay, as i will not be using the stock airbox, but rather a short curved tube and cone filter....
    If this is what you want to do you should look into a 323i afm and box, left side fender is stock mounting.

  8. #8
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    I'll chime in when I have more time...

    '81 320i turbo | t25, 931 CIS, 240hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  9. #9
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    Thanks Josh... i'll check back

  10. #10
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    Quote Originally Posted by jrcook320 View Post
    I'll chime in when I have more time...
    ha, ha, spoken like a new parent, congrats BTW

  11. #11
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    I spent almost an hour typing up a response tonight, firefox crashed and I now have a virus...

    '81 320i turbo | t25, 931 CIS, 240hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  12. #12
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    Quote Originally Posted by jrcook320 View Post
    I spent almost an hour typing up a response tonight, firefox crashed and I now have a virus...
    That's what happens when you let the kids use your computer!

    Download Spybot Search & Destroy, and AVG Free (grisoft) from download.com.
    Install "Spybot Search and Destroy" as a tool - do all the updates/immunization/scans/reboots.
    Uninstall your old AV program, and then install "AVG (grisoft) anti-virus".
    You may have to disconnect your internet cable if it is a "downloader virus" that keeps coming back.

    Hope that helps, we don't need you passing colds to everyone .
    Tbd

  13. #13
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    Here is a diagram of a stock e21 WUR:


    And for comparison, here is a vacuum sensing WUR.:


    A boost sensing WUR works just like the vacuum sensing WUR, but not shown in the diagram is port feeding the chamber above the boost diaphragm, and a coil spring on the bottom side of the diaphragm which preloads the diaphragm at the top stop, so at rest it is at it's leanest setting. This type of WUR has 2 ports, one above and one below the diaphragm. If you leave the lower port disconnected, boost pressure will push the diaphragm down for max enrichment when the turbo spools. I think that this is the most simple and reliable way to plumb up a boost sensing WUR.

    However, On a stock audi/volvo, there is also a vacuum line with a check valve installed to hold vacuum in the lower chamber. This has the effect of providing max enrichment as soon as there is throttle tip in, as well as when the turbo spools.

    here is a diagram of the stock volvo 240 plumbing:


    And how I ran mine for a year:


    When the motor is running (at idle), a vacuum is pulled on both ports. The diaphragm doesn't move due to the spring pushing it to the top stop. When you tip into the throttle, manifold pressure rises in the upper chamber but vacuum is held in the lower chamber and this pressure differential pulls the diaphragm down. Under boost the diaphragm is pushed down. In stock form, this circuit is only used when the motor is cold.

    I wasn't a fan of the setup shown in the because when you're cruising at steady throttle for long periods the check valve slowly leaks and pressure will slowly rise in the lower chamber, allowing control pressure to rise which ends up leaning your mixture out until you let off the throttle to pull vacuum again. It's much better to tune the control pressures to run without that system and run a single boost line to the top port if you need boost enrichment. When I tried to run my car with a single boost line plumbed to the top port it had terrible throttle response. This was partially due to a horribly mismatched fuel distributor/AFM combo (I was running the 240 turbo FD on a PVR v6 air flow meter which I THOUGHT was a porsche 924 turbo AFM), but I could have tuned it out by simply lowering my control pressure.

    I was running about 54 psi warm control pressure with no vacuum applied (which is about stock for a volvo 240t WUR). With the WUR plumbed with the check valve, here were my pressure readings:

    Vacuum/boost line to top port, vacuum line w/ check valve on bottom port (volvo plumbing):
    WCP @ 0" Hg = 54 psi (fuel pump jumpered)
    WcP @ idle, 19" hg = 47 psi
    Throttle blip to 5" Hg = CP dropped to 30 psi

    You can see that at idle, there was enough vacuum being pulled on the lower port that it was pulling control pressure down to 47 psi, resulting in a much richer mixture than the base 54 psi setting I got with just a single line plumbed. If you find that your car stumbles with a single line on the top port, you should try to lower control pressure a little at a time until it goes away. You may not have that issue at all with a properly matched volvo 240 turbo fuel distributor and air flow meter. I've never actually had that setup on my car so I don't know. (drew??)
    Last edited by jrcook320; 01-25-2010 at 12:56 AM.

    '81 320i turbo | t25, 931 CIS, 240hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  14. #14
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    thanks josh, that really helps... I will try leavin the bottom port to atmo first and adjusting control pressure... It's great when the simple ways are the best ways (i think that is how i have it now, just cause only that one port where the boost goes holds a normal sized line.
    Last edited by greenmachine78; 01-25-2010 at 01:12 AM. Reason: sat on page too long before hitting "go"...

  15. #15
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    Quote Originally Posted by greenmachine78 View Post
    thanks josh, that really helps... I will try leavin the bottom port to atmo first and adjusting control pressure... It's great when the simple ways are the best ways (i think that is how i have it now, just cause only that one port where the boost goes holds a normal sized line.
    I should mention, I let the bottom half of mine vent to atmosphere as well.


  16. #16
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    I'm sorry to bring up an old thread but I'm looking into getting the volvo 240 turbo WUR and was wondering where the red hoses plug into? I know where everything else goes. Thanks!

  17. #17
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    I've learned a few things since I posted that info. It's better to keep it simple. Run a single boost line to the top port and that's it.

    It's very likely that you'll have WAY too much boost enrichment with the stock 240 turbo control pressure settings. Stock 240 turbo control pressure around 53 psi, and the on-boost control pressure is set to around 30 psi.

    After switching to a matched fuel distributor/AFM combo (from a porsche 924 turbo), that 30 psi on-boost control pressure sent my mixture so rich it was off the map (somewhere below 10:1) and would bog out. I had to raise the on-boost control pressure by pushing in the lower diaphragm stop.

    I applied "boost" pressure with my air compressor while monitoring control pressure, then used c-clamps to slowly dial bring the on-boost control pressure up. After a couple test drives I arrived at around 48 psi for on-boost CP (vs. 53 psi at all other times). This yeilds a clean and lean 14.7-15 while cruising and a nice fat 11.5:1 as soon as the turbo spools.

    '81 320i turbo | t25, 931 CIS, 240hp, 13.92@100mph | 2.2L m10 Turbo Build | My E21 Videos |

  18. #18
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    Thanks for the reply and as of right now I have the stock FD and AFM but in the future I'll upgrade! The boost sensing WUR is a start for me right now.

    Do you think I'll have any issues with the stock FD and AFM? Or will I be running too rich?

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