comp ratio and timming

Discussion in 'PSI Superchargers Tech Questions' started by Tommy, Jan 26, 2009.

  1. Tommy

    Tommy Super Comp

    Joined:
    Jul 27, 2003
    Messages:
    64
    Likes Received:
    0
    Somebody told me the fast alch funny cars with a screw and brad heads are running 12 to 1 comp with lower timming but then someone else said 11 to one with 27 degrees timming. anybody now what the truth is.:cool:
     
    #1
    Tommy, Jan 26, 2009
  2. Creech

    Creech Member

    Joined:
    Dec 5, 2008
    Messages:
    307
    Likes Received:
    1
    Ask ten different crew chiefs and get ten different answers. That's why you don't see two crew chiefs on the same car. Except Force; and you never see Coil or Fedderly with black eyes? I still haven't figured out how that works.

    It depends on a lot of variables. Load; gear ratio, altitude, temperature and humidity. If its humid you can always put more timing in it. Fuel system? I can tell you 29 is about the outer limit for a msd 44 and a screwblown hemi.

    How's it go again Will? If the intake's still tight put more lead in it.
     
    #2
    Creech, Jan 26, 2009
  3. thjts

    thjts New Member

    Joined:
    Jun 14, 2005
    Messages:
    254
    Likes Received:
    1
    As Marty has said, everyone's different. However, lower static compression ratio will give you a larger tuning window. Some folks may need that, some don't.

    Paul.
     
    #3
    thjts, Jan 27, 2009
  4. jonimus333

    jonimus333 New Member

    Joined:
    Nov 7, 2007
    Messages:
    504
    Likes Received:
    0
    Timing/ comp

    Not sure but thought I would throw this out, I have a friend who runs a TAFC. He told me that they were lowering the comp. and it was running better. Many things contribute to this.So, this is not Gospel. Just hear say. Try shorter rods / thicker head gaskets. and let us know.. Knowledge is a wonderful thing. Don
     
    #4
    jonimus333, Jan 29, 2009
  5. Mike Canter

    Mike Canter Top Dragster
    Staff Member

    Joined:
    Mar 10, 2004
    Messages:
    4,630
    Likes Received:
    189
    Here is the problem...the guy that can't find the right tuneup is not the guy you want to tell you what the right compression ratio is. The guy that is not running competetive ETs is not the guy you want to tell you the right compression ratio. They are all looking for the right combination. You can have too high of a CR and have to throw more fuel at it with less timing or you can be too low and lean it out and add timing. You can cover up one problem by making another problem. I say lets wait and maybe Frank Manzo, or Steve Harker, Jay, or Mick will jump in here and tell you what their compression ratio's are so we can compare and see if they are the same or not, yea, keep waiting (LOL):D I can bet you this they are probably close but not exactly the same just like their bores and strokes.
     
    #5
    Mike Canter, Jan 29, 2009
  6. eli

    eli Banned

    Joined:
    Dec 24, 2005
    Messages:
    1,657
    Likes Received:
    1
    If you shorten the rods or use thicker head gaskets you lose your quench area, the best way is to chuck up the piston and take material off the top of the dome. ;)
     
    #6
    eli, Jan 29, 2009

Share This Page





XenPorta 2 PRO © Jason Axelrod from 8WAYRUN.COM