jp4 head j4 cams

  1. Established Member Joined: Apr 2006 torquay (England) Posts: 1993 supercharged vts. 1.1 saxo. accord type r
    #1
    am wandering wat needs to be done.
    i have catcam 708s for j4 head.
    wat is needed to be done to fit to jp4 head if anything.
    remember reading somewhere something needed doing
    cheers
    adz
  2. Saxperience Post Whore Joined: Jan 2007 Shropshire Posts: 9994 Moonstone Blue 106 GTi
    #2
    followers, collets etc iirc ptv is close aswell with 708s and the bv jp4 head
  3. Established Member Joined: Apr 2006 torquay (England) Posts: 1993 supercharged vts. 1.1 saxo. accord type r
    #3
    so i swap the collets to ones used in j4 head, and i know i should prob know these but (ptv) and (bv) ????????
  4. Saxperience Post Whore Joined: Jan 2007 Shropshire Posts: 9994 Moonstone Blue 106 GTi
    #4
    piston to valve contact and big valve head lol

    I am pretty sure basically you keep valve in but everything else like the springs followers etc you change as they are supposedly stronger in the J4 plus you will be revving yours higher won't you?
  5. Frequent Poster Joined: Aug 2008 ESSEX Posts: 727 106 GTi Turbo
    #5
    yes, you use everything from the J4 head. springs, caps, cams etc.

    - colin.
  6. Established Member Joined: Apr 2006 torquay (England) Posts: 1993 supercharged vts. 1.1 saxo. accord type r
    #6
    Ye running higher rpm. So just swap all that over. Use j4 pulleys 2.
    also at the mo i have a 1.5 mm j4 headgasket. Do i need to change this?
  7. Established Member Joined: Jan 2008 Posts: 1802
    #7
    As above really, but also you'll want forged pocketed pistons. Any reduction in compression ratio affects mpg and torque figures throughout the entire rev range. Lower the C/R, lower the torque and efficiency.

    Andy
  8. Established Member Joined: Apr 2006 torquay (England) Posts: 1993 supercharged vts. 1.1 saxo. accord type r
    #8
    im running oversized forged lo comps for boost andy.
  9. Super Moderator Joined: Nov 2009 Cambridge(ish), UK. Posts: 10581 BMW 5x M50d.
    #9
    Quote:
    Originally Posted by adzvtr View Post
    im running oversized forged lo comps for boost andy.
    If you're running boost you wont want 708's in there...
  10. Established Member Joined: Apr 2006 torquay (England) Posts: 1993 supercharged vts. 1.1 saxo. accord type r
    #10
    708s are fine with charger m8
  11. Super Moderator Joined: Nov 2009 Cambridge(ish), UK. Posts: 10581 BMW 5x M50d.
    #11
    Quote:
    Originally Posted by adzvtr View Post
    708s are fine with charger m8
    When I was talking to John @ GMC a few weeks back he didn't agree. Something to do with the overlap iirc.
  12. Established Member Joined: Apr 2006 torquay (England) Posts: 1993 supercharged vts. 1.1 saxo. accord type r
    #12
    But yet he is running a similer specd cam in his own charged car and trying to sell it now. 708S seem fine on boosted cars. From wat i have seen.
  13. Super Moderator Joined: Nov 2009 Cambridge(ish), UK. Posts: 10581 BMW 5x M50d.
    #13
    Quote:
    Originally Posted by adzvtr View Post
    But yet he is running a similer specd cam in his own charged car and trying to sell it now. 708S seem fine on boosted cars. From wat i have seen.
    My understanding is high-duration cams in a forced setup result in a significant loss of low down torque and significantly increased lag, whilst making more peak power higher up the rev range. IE, they do make more peak power overall than standard cams, but as the expense of drivability and mid-range power.

    That's the reason turbo spec cams exist, after all.

    I'm open to suggestion otherwise, but this is my understanding.
  14. Established Member Joined: Jun 2008 nuneaton Posts: 1796 LY R26
    #14
    But if you look at the turbo spec cams from catcams, the inlet can is actually the cam used with the 708s, it's just the exhaust cam that has a lower duration and lift, more of a ph2 type spec where they use the newmans ph3 inlet and ph1 exhaust cams.
  15. Saxperience Forum Bum Joined: Jan 2003 Scotland Posts: 3380
    #15
    Quote:
    Originally Posted by RossDagley View Post
    My understanding is high-duration cams in a forced setup result in a significant loss of low down torque and significantly increased lag, whilst making more peak power higher up the rev range. IE, they do make more peak power overall than standard cams, but as the expense of drivability and mid-range power.

    That's the reason turbo spec cams exist, after all.

    I'm open to suggestion otherwise, but this is my understanding.
    I don,t think 200@wheels @5000rpm could be considered as lacking in mid range power
    It s not as simple as just picking a cam ,but where you set it up and all the other bits round about it,tand depending on what the exact question i am asked will depend on my answer as to best option.
    and a turbo engine does not respond the same as an s/c engine so simply fitting turbo cams is not always the answer
  16. Super Moderator Joined: Nov 2009 Cambridge(ish), UK. Posts: 10581 BMW 5x M50d.
    #16
    Quote:
    Originally Posted by axsaxoman View Post
    I don,t think 200@wheels @5000rpm could be considered as lacking in mid range power
    It s not as simple as just picking a cam ,but where you set it up and all the other bits round about it,tand depending on what the exact question i am asked will depend on my answer as to best option.
    and a turbo engine does not respond the same as an s/c engine so simply fitting turbo cams is not always the answer
    Thanks for the clarification. I'm making 200@wheels @5000(ish) rpm on standard J4 cams so would you say there's no benefit either?

    Every day is a school day!