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myths about pr4 head and p75 head shattered

Discussion in 'General Tech and Maintenance' started by saturn_boy96, Apr 27, 2004.

  1. saturn_boy96

    saturn_boy96 88 C1V1C 53D4N DR1V3R

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    Dec 13, 2002
    Location:
    Sheridan, WY
    i disassembled two heads last night. one was from a 91 integra ls (usdm b18a1), and the other was from what i was told a jdm honda orthia (jdm b20b). so that is where i am getting my info from.

    head design:
    basically the same, newer has marginally larger ports. both are designed to use dual valve springs but don't.

    valves:
    exactly the same size on both itake and exhaust sides. (some people say they are different)

    valve springs:
    old: progressively wound, exhaust are taller than intake
    new: linearly wound, exactly the same on both sides, shorterand lighter than the old springs.

    valve retainers:
    old: almost twice as thick as the new ones and about a half mm larger in diameter
    new: thinner and samller diameter

    cams:
    i can't measure so we'll belive what people are saying in that the new ones are better.

    in my project motor i am going to try to combine the good peices off both heads and we'll see what kind of number i can get this thing to have on all oem stuff. i'll try to post numbers later but since i am in wyoming, it will be hard to find a dyno( i don't think there is one in the entire state). but i will do my best and will definately have numbers once project Getto Star is on boost. :)
     
  2. JDMilan

    JDMilan Senior Member

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    good info
     
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