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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

    Likes Received:
    Dec 13, 2002
    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.

    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

    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

    Likes Received:
    May 11, 2003
    Boca Raton, FL
    good info
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