P-valve Question - Page 2
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Page 2 of 5 FirstFirst 1 2 3 4 5 LastLast
Results 16 to 30 of 72
Like Tree2Likes
2009-2014 Cadillac CTS-V Performance Mods Discussion, P-valve Question in Cadillac CTS-V Series Forum - 2009-2014; Originally Posted by backup I am really curious about this mod. I smell cheap HP! Here is what I found: ...
  1. #16
    CadV is offline Cadillac Owners Connoisseur
    Automobile(s): V2
    Join Date
    Jul 2004
    Location
    TX
    Age
    37
    Posts
    1,076

    Re: P-valve Question

    Quote Originally Posted by backup View Post
    I am really curious about this mod. I smell cheap HP! Here is what I found:

    1. Disconnected O line. Found boost seemed slower to build and didn't quite reach 9psi
    2. Disconnected X line with O still disconnected. Seemed very similar to step 1 - slower to build boost and barely reached 9psi.
    3. Re-connected O, left X disconnected. Seemed to build boost VERY fast, and quickly pegged 9psi. Seat of the pants meter felt this was more responsive and more power, perhaps from faster boost build (more power sooner).

    I then reconnected all vaccuum/pressure lines and disconnected the electrical connector to the O/X valve device. Noticed it would still move the boost gauge while reving in neutral, haven't had a chance to drive it like that yet.

    I want to know what the X, O, P and V lines do, and how the valve and pressure regulator work to control boost. I don't understand how this functions. I got a hunch doing some tricks here will yield power. I want to know if the measured boost pressure as shown on the gauge is used to control the boost level, or whether it is governed by a separate mechanism such as this XOPV vaccuum/pressure valve assembly. It makes me think the 15psi shown above is real, although I don't know why the gauge would drop to zero - if the gauge information is indepependent from the boost control mechanism (the computer reading 9.0psi is not used to govern that boost).

    I do know the X/O valve is NOT the boost gauge as I was getting readings with the thing disconnected, both electrically and vaccuum lines.
    Cool post and I will play along. I will have time this weekend to mess around with it. Let me know what you find out and I will try it and see if we get the same results. I will also talk to my GM buddy and see if I can find out what POXV do.

    If you take the unit out you can grab the silver bar in this post:
    http://www.cadillacforums.com/forums...ml#post1943911

    and push it in and out. Once you cap p it is much harder to do so I assume boost is preserved.

  2. #17
    The Tony Show's Avatar
    The Tony Show is offline See you in the funny papers
    Automobile(s): 04 CTS-V, 05 STS, 07 SRX- All sold :(
    Join Date
    Dec 2004
    Location
    The Internet
    Posts
    26,274

    Re: P-valve Question

    You guys are ballsy, I'll give you that.
    Rest in Peace, J.D. (aka Dirt_Cheap_Fleetwood)

  3. #18
    CadV is offline Cadillac Owners Connoisseur
    Automobile(s): V2
    Join Date
    Jul 2004
    Location
    TX
    Age
    37
    Posts
    1,076

    Re: P-valve Question

    Here is a diagram


  4. #19
    Nutz's Avatar
    Nutz is offline Cadillac Owners Connoisseur
    Automobile(s): 09 CTS-V a tuxedo with a jetpack!
    Join Date
    Oct 2007
    Location
    Northeast Ohio hammer down
    Age
    46
    Posts
    2,451

    Re: P-valve Question

    Well, somebody's gotta ask. Curiosity tugs. Which one is the "X" line? Or are they marked?

    Not that I would unhook it without seeing substantial evidence here to support or deny any imminent dangers.

  5. #20
    CadV is offline Cadillac Owners Connoisseur
    Automobile(s): V2
    Join Date
    Jul 2004
    Location
    TX
    Age
    37
    Posts
    1,076

    Re: P-valve Question

    Quote Originally Posted by Nutz View Post
    Well, somebody's gotta ask. Curiosity tugs. Which one is the "X" line? Or are they marked?

    Not that I would unhook it without seeing substantial evidence here to support or deny any imminent dangers.
    Check the first picture in post 6. See the x and o in green? x is cable 2 in the diagram. o and p is cable 4. cable 3 is v and other end is not labeled on mine.

  6. #21
    Nutz's Avatar
    Nutz is offline Cadillac Owners Connoisseur
    Automobile(s): 09 CTS-V a tuxedo with a jetpack!
    Join Date
    Oct 2007
    Location
    Northeast Ohio hammer down
    Age
    46
    Posts
    2,451

    Re: P-valve Question

    Wow, small. Thanks.

  7. #22
    backup is offline Cadillac Owners Fanatic
    Automobile(s): 2009 CTSV, silver, manual
    Join Date
    Mar 2009
    Location
    Indiana
    Posts
    213

    Re: P-valve Question

    Great diagram! thanks. Got a legend to go with that? Knowing the official nomenclature for these parts would help understand what they do.
    CadV, did you cap the port in the supercharger housing that X connect to?

    Thinking this through a bit, here is what I have. The X line port is under vaccuum at idle, and presure at boost. This pressure feeds the X port on the XO valve. The O line feeds the P port on the pressure regulator device. The other port on the pressure regulator device is the V line that connects to something under the supercharger. I was thinking the V line transferred intake manifold vaccuum to the regulator device, to be balanced by the pressure from the P port, but that doesn't make sense because under boost there is no manifold vaccuum. So what the hell does the V line connect to?

    If pressure on the P port offsets vaccuum on the V line, and the two work together for some equilibrium to regulate boost, then I can see how capping the P port would allow the V line to maximize its variable. Assuming the V line is the positive feedback signal (increasing boost) then we would not want to cap that, but would want to cap the negative feedback signal (the P port). Capping the O port on the supercahrger housing might preserve some amount of manifold pressure just from eliminating the release that would occur if uncapped. Disconnecting the electrical connection on the XO valve should have no effect as long as the P port is capped. This is what I will test next.

    Is there such a thing as a wastegate on a supercharger? How is excess boost bled off? Or is it all controlled with a throttle or pressure plate (which would explain the pressure regulator adjusting a butterfly valve of some sort)? Experts we need your help!

  8. #23
    Nutz's Avatar
    Nutz is offline Cadillac Owners Connoisseur
    Automobile(s): 09 CTS-V a tuxedo with a jetpack!
    Join Date
    Oct 2007
    Location
    Northeast Ohio hammer down
    Age
    46
    Posts
    2,451

    Re: P-valve Question

    Just what us men need, another difficult to understand little p valve that can make more blower pressure and increase whining AND can be quite volatile and very expensive to maintain if not delicately handled by an experienced professional.
    O.k, o.k, Sorry guys the door was open.

    Back to the regularly scheduled technical discussion.

  9. #24
    CadV is offline Cadillac Owners Connoisseur
    Automobile(s): V2
    Join Date
    Jul 2004
    Location
    TX
    Age
    37
    Posts
    1,076

    Re: P-valve Question

    Got a legend to go with that?
    I will try to get it tomorrow.

    CadV, did you cap the port in the supercharger housing that X connect to?
    No I did not. I did not cap the other end of P either.

    Quote Originally Posted by backup View Post
    So what the hell does the V line connect to?
    See the bolt holes on the blower snout? Go down you you will see a port pointing passenger side. V goes into that.

  10. #25
    backup is offline Cadillac Owners Fanatic
    Automobile(s): 2009 CTSV, silver, manual
    Join Date
    Mar 2009
    Location
    Indiana
    Posts
    213

    Re: P-valve Question

    Quote Originally Posted by CadV View Post
    See the bolt holes on the blower snout? Go down you you will see the a port sticking out. V goes into that.
    Yeah but what is that? What does the V port connect to, inside the engine? If that is intake manifold, then the pressure should be the same as the supercharger housing. If the V port offsets pressure from the P port then I would assume it is pressure, not vaccuum, and the net presssure sets the regulator position. I am at the edge of my understanding of engine design, so somebody help me here. Maybe there is a difference between the pressures at the supercharger core (X port) and the intake manifold (V port)? And this difference regulates the boost??

    I just capped my P port line with a heavy dose of electrical tape. If my theory is right then I should see increased boost. Might need to cap the X port on the supercharger housing also. This also jives with what I saw by disconnecting the X line and the increased boost response (the V port was left unbalanced or unrestrained). But at atmospheric pressure the P port may have still offset the V line impact, so capping it might let the V line vaccuum (or pressure) maximize its effect. I will find out!

  11. #26
    CadV is offline Cadillac Owners Connoisseur
    Automobile(s): V2
    Join Date
    Jul 2004
    Location
    TX
    Age
    37
    Posts
    1,076

    Re: P-valve Question

    Quote Originally Posted by backup View Post
    Yeah but what is that? What does the V port connect to, inside the engine? If that is intake manifold, then the pressure should be the same as the supercharger housing. If the V port offsets pressure from the P port then I would assume it is pressure, not vaccuum, and the net presssure sets the regulator position. I am at the edge of my understanding of engine design, so somebody help me here. Maybe there is a difference between the pressures at the supercharger core (X port) and the intake manifold (V port)? And this difference regulates the boost??

    I just capped my P port line with a heavy dose of electrical tape. If my theory is right then I should see increased boost. Might need to cap the X port on the supercharger housing also. This also jives with what I saw by disconnecting the X line and the increased boost response (the V port was left unbalanced or unrestrained). But at atmospheric pressure the P port may have still offset the V line impact, so capping it might let the V line vaccuum (or pressure) maximize its effect. I will find out!
    You lost me at regulator position haha. If you find anything let me know and I will test it too.

  12. #27
    CadV is offline Cadillac Owners Connoisseur
    Automobile(s): V2
    Join Date
    Jul 2004
    Location
    TX
    Age
    37
    Posts
    1,076

    Re: P-valve Question

    Here is the legend...


  13. #28
    wait4me's Avatar
    wait4me is offline Cadillac Owners Connoisseur
    Automobile(s): 11v,2 09 v's,2 05 v's,5 GTM supercars,viper,volt,2012 karma
    Join Date
    Jan 2009
    Location
    warsaw indiana
    Posts
    2,986

    Re: P-valve Question

    The p port is basically for overboost situations. The P or "Protection" port will bleed off boost by opening the boost bypass valve when it reaches levels over stock. It is that way so even if you remove the limits inside the computer to still allow boost past 10psi, the valve will try to bleed off boost on its own. So by capping the line and venting the p valve will make it apply full boost without reventing the boost into the manifold to be recirculated.

  14. #29
    stealthjr is offline Cadillac Owners Fanatic
    Automobile(s): '09 Thunder Gray CTS-V
    Join Date
    Apr 2005
    Location
    Texas
    Age
    45
    Posts
    156

    Re: P-valve Question

    Quote Originally Posted by wait4me View Post
    The p port is basically for overboost situations. The P or "Protection" port will bleed off boost by opening the boost bypass valve when it reaches levels over stock. It is that way so even if you remove the limits inside the computer to still allow boost past 10psi, the valve will try to bleed off boost on its own. So by capping the line and venting the p valve will make it apply full boost without reventing the boost into the manifold to be recirculated.

    Thanks for the clarification Jesse. So, I assume there is ZERO benefit to messing with this UNLESS one has a pulley to increase boost over stock levels right???

    Also, to avoid some confusion...you are saying to "CAP or plug" the P-Port LINE and vent or leave the "nipple" that the P-Port line was attached to...open? It looks like CADV capped the "nipple" on the valve and not the "line" as you stated. Just making sure I understood you correctly so folks on here dont mess something upo or do something backwards because of a misunderstanding of words.

    Thanks,

    Robert

  15. #30
    wait4me's Avatar
    wait4me is offline Cadillac Owners Connoisseur
    Automobile(s): 11v,2 09 v's,2 05 v's,5 GTM supercars,viper,volt,2012 karma
    Join Date
    Jan 2009
    Location
    warsaw indiana
    Posts
    2,986

    Re: P-valve Question

    Correct, Even though you get about .5 lbs of boost extra by tweeking the bypass valve on the stock one to make it fully closed. Even a slight gap will cause a pressure loss, so make sure it is fully closed.

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting