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header comparison

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by JTB, Mar 7, 2002.

  1. JTB

    JTB 1/2 ton status

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    Anyone know where I can find a comparison of ramhorn exhaust manifolds vs. headers? My main objective is low-end torque and I have been told by some that the ramhorns are better for torque and by others that the right header will produce much more torque. I would run Doug Thorley headers designed for low end. The ramhorns i am running are not the corvette ones. Anybody have evidence or experience with this?
    Jeff
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    The non-corvette ramshorn manifolds are very restrictive. The corvette ramshorns are 2 1/2" diameter and are much better than the rest of them but still not as good as a header. I would suggest a shorty style header of a good brand with a 2 1/2" Y pipe into a single 3" exhaust. Make sure you use a good muffler such as a gibson or flowmaster and if you have a cat make sure you go with a high-flo type
     
  3. JTB

    JTB 1/2 ton status

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    Thanks 4x4high, anyone else want to comment?
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    According to desktop dyno (which you can take for what its worth, its been compared prety favorably to real dynos with the right info) headers do hurt the low end, but its slight, and much less damage done than the overall gains.
     
  5. JTB

    JTB 1/2 ton status

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    just movin it back up again. I would really like to know what kind of gains I should expect before I drop $$$ into new headers.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, again using desktop dyno to get some idea of what kind of changes, the motor I'm building, assuming "high performance manifolds and mufflers" at 2000RPM I've got 155hp. 406ftlbs torque at same. HP peak is 273@ 4/4500RPM(flat)

    With "small tube" headers, those numbers change to 167HP and 439 ftlbs at 2000RPM. HP peak is now 309@4500, and tq is 439@2000.

    This is with a "small" cam, vortec heads, and TPI, so your numbers of course would vary.

    Since most dyno's don't measure under 2000RPM anyway, it's kind of hard to tell whats going on below that RPM. But according to the DD2K graph, the manifolds produce a flatter torque curve, but it's less power overall. At 2000RPM with headers, torque is already FALLING, (meaning it was higher to start with) whereas with Manifolds, it starts and stays flat.

    I'd say almost without question, you are going to make more overall power with proper headers.
     
  7. JTB

    JTB 1/2 ton status

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    Thanks Dorian, i think Im sold. I ran a search for desktop dyno but only got a tire size/ rpm table. Where did you find the header comparison?
    Jeff
     

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