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Valve spring pressure

Discussion in 'COMP Cams Support Forum' started by Russ67scode, Dec 8, 2019.

  1. Russ67scode

    Russ67scode Member

    Joined:
    Oct 6, 2016
    so I have an FE engine with twin turbos
    Before the turbo’s the engine reved fine to 6500 rpm
    Now with the turbo’s installed it will barely go to 5800 rpm. The guy at the dyno place said my exhaust springs are not strong enough and the exhaust header has more pressure than the intake when in boost
    So my question is how do you determine what springs to run ? Can’t measure the pressure in the headers
    Thanks Russ
     
  2. CPG Tech Support

    CPG Tech Support Administrator Staff Member

    Joined:
    Jun 21, 2019
    If you have more pressure in the exhaust, that means you have too much back pressure in the exhaust and you need a more free flowing exhaust or need to change the cam specs so you reduce the back pressure in the exhaust.
     
  3. Russ67scode

    Russ67scode Member

    Joined:
    Oct 6, 2016
    I believe the exhaust is not the problem other than the turbo’s themselves
    Prior to the turbo’s it reved to 7000 rpm
    This engine was built by Blair Patrick
    Here is the entire exhaust
    upload_2019-12-23_8-25-24.jpeg
     
    Last edited: Dec 24, 2019
  4. CPG Tech Support

    CPG Tech Support Administrator Staff Member

    Joined:
    Jun 21, 2019
    What are your are your actual cam specs?
     
  5. Russ67scode

    Russ67scode Member

    Joined:
    Oct 6, 2016
    Talked to engine builder he said change gears and shift engine at lower RPM he is pretty Secret about his build specs I do know it’s low 600 lift and around 240@.050
    Hyd roller. I’m pretty sure Blair gets cams from you
     
  6. CPG Tech Support

    CPG Tech Support Administrator Staff Member

    Joined:
    Jun 21, 2019
    Gearing can affect the rpm also. Cam specs play a big part with back pressure with a turbo also. Without cam specs, it will be hard to determine the exact problem.
     
  7. Russ67scode

    Russ67scode Member

    Joined:
    Oct 6, 2016
    Thanks . I’ll try the gear change first. Pretty easy change and I was putting in a spool so the rear will be apart anyway
    At 20 lbs of boost it did make a bunch of torque until the fuel pump ran out at 4000 rpm rpm Since then fixed the fuel pump problem see attached dyno pic at 3500 rpm
     

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