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How much boost ?

Discussion in 'Tractor/Loader/Backhoes' started by hofdoug, Jul 30, 2011.

  1. hofdoug

    hofdoug Member

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    I have a 97 214-s JCB and it only makes about 9 lbs of boost under a load what should it have?
     
  2. xcmark

    xcmark Senior Member

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    sounds about right for equipmnet constant speed motors . what type of waste gate on the turbo does it have ? spring type is the most common and rarely has issues. I have a 2003 JCB skid steer with a perkins 92 hp 4 banger in it . The turbo waste gate is a spring type on it also. Basicly the spring provided resistance for the boost pressure to push against and once it hits the spec it starts to blow open and let the boost blead off so you dont replace your head gasket.
     
  3. John C.

    John C. Senior Member

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    Turbo boost is usually measured in inches of mercury which comes out to about twice what a PSI reading is. Nine PSI would be about eighteen inches of mercury which is actually quick a bit of boost for a small motor.

    How did you measure it? Was the engine at high idle with a full load?
     
  4. hofdoug

    hofdoug Member

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    9 lbs at full load. My Dodge diesel runs 38 at full load
     
  5. tctractors

    tctractors Senior Member

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    The boost pressure is not as important as the rpm speed at high idle then full load speed, some engines will drop about 150 rpm on full load, the latest engines are often set to hold the same speed at high idle (no load) as on full load, when on full load this is the point to measure your turbo boost pressure, 9 psi would sound a bit low.
     
  6. MrKomatsu

    MrKomatsu Senior Member

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    8 sounds a little low......be sure you have full rpm and full load.....12-20 psi.....
     
  7. MB@mp218

    MB@mp218 Member

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    9 PSI sounds low. Check that all the hose clamps are tight and hoses completely on between the turbo and the intake manifold. A sign of loose clamps, etc is are whistling sounds at full throttle, especially if the engine is under load, i.e. when driving down the road in 4th gear at high idle? Most boost problems I've encountered are due to hoses being loose or just plain "blowing off" and being disconnected. A hose could also have a hole/crack and be leaking.

    Although not related to your question when was the fuel filter last changed? Dirty fuel filters really limit power. Secondly, a dirty air filter will too. I hope this helps you nail down the real source of the problem.
     
  8. mitch504

    mitch504 Senior Member

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    Every factory installed turbo boost guage I've seen measured in inches of mercury, if you are using a guauge that measures in pounds, 9 pounds is 18.3 inches of mercury.