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hp loss???

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by 72jim, Aug 9, 2001.

  1. 72jim

    72jim 1/2 ton status

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    ok i live in phx az and when i'm driving my 72 jimmy with a 350, 4" lift and 35" tires around the "valley" it does ok horse power wise. but when i go up north about two hours away and maybe a 2000-3000 elevation difference my horse power drops alot. i've tried readjusting the carb once i get there but it still doesn't seem to run right.any clues?

    72 jimmy
     
  2. ImpalaSS

    ImpalaSS 1/2 ton status

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    higher the elvation the more power loss you will have........ especily on a carbed engine

    68 SWB 4x4 1 of 1,449 made 327, 465 4 speed, rockwell tcase, edelbrock performer intake+carb, MSD pro billet http://communities.msn.com/68K10
     
  3. 72jim

    72jim 1/2 ton status

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    well i know i'll lose some hp with elevation but there has to be a better way

    72 jimmy
     
  4. Crushergmc

    Crushergmc 1/2 ton status

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    You can actually gain some power by lowering your octane at higher elevations. It has to do with the oxygen levels and atmospheric pressure I guess.

    "KEEP IT DOWN"
    70 Jimmy, 454, 2wd
    56 GMC, Big Window
     
  5. Klef72K5

    Klef72K5 1/2 ton status

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    Ram Jet 502! No more needs to be said! LOL!

    <a target="_blank" href=http://wsphotofews.excite.com/031/rw/Jo/og/t488200.jpg>http://wsphotofews.excite.com/031/rw/Jo/og/t488200.jpg</a>
     
  6. 72GMCJIMMY

    72GMCJIMMY 1/2 ton status

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    When I lived in Colorado I was always between 5000 and 10000 foot altitude. What worked for me was to lean the carburetor, advance the timing, and use a high octane fuel.
     
  7. Steve_Chin

    Steve_Chin 1/2 ton status

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    I guess that the question that needs to be posed is: What did you do to "adjust" the carburetor? If you only messed with the idle mixture screws, you were only affecting the idle mixture and you would see no power gains. If you re-jetted, you should have had some of the power come back (although due to the relative air density you will not see it all come back).

    The only solution to mitigate the problem is forced induction (supercharging, turbosupercharging). Those methods will increase the density of the air in the intake tract but they also has their own drawbacks and limitations.

    Fuel injection will reduce the amount of power loss. It will not prevent it.
     
  8. 72jim

    72jim 1/2 ton status

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    i adjusted the mixture and the idle screws and it ran a bit smoother.from 1and 1/2 turns out to about 2 and 1/4 out and a 1/4 turn in on the idle. i would love to change to fuel injection but i can't afford it at the moment. i was also thinking i could set up a "ram air" type set up but living in the desert would make it hard to keep the dust out. any thaughts on "ram air" set ups? i was thinking of pulling the air from around the wiper arm cowl area at the bottom of the windsheild.

    72 jimmy
     
  9. Steve_Chin

    Steve_Chin 1/2 ton status

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    That's probably the best place for a cowl induction setup, but make sure that the section you draw the air from is isolated from the section that supplies air to the cabin of the truck. It will help a very little bit at altitude (my Trans Am has a functional shaker on it and it lost power going through the Sierras, but not as much as when the shaker is plugged).

    Dust? There are so many open holes under and in front of the Blazer that dust is going to get into the air cleaner no matter what you do. A cowl induction or Ram Air system isn't going to appreciably increase the amount of dust intorduced to the filter element.
     
  10. 72jim

    72jim 1/2 ton status

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    true.....thanks

    72 jimmy
     

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