Truth about NPI vs PI

Discussion in '96-04 - 2V Specific' started by blackfang, Jan 12, 2006.

  1. MAXX RS4

    MAXX RS4 Member

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    OK, here are some pics.

    Hopefully someone will tell me that it's a PI intake so I'll believe that my cars even faster than it is! :D

    But is anything else different from stock as well? Besides the fipk of course..

    EDIT: Forgot to add the pics lol

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    EDIT #2: I can get larger versions of the pics too if needed..
     
  2. BlueStangGT

    BlueStangGT New Member

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    Sorry man, that is not a PI intake. It look like someone either grinded the pony off of the plenum, put a different plate on it, or it could be a different plenum(don't think so though). :dunno:
     
  3. MAXX RS4

    MAXX RS4 Member

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    :'(
     
  4. cinder

    cinder New Member

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    this is a great post I just got a 98 and don't really know a lot about 4.6 performance.Very helpful now I have some direction to go in thank you
     
  5. bullitt98

    bullitt98 New Member

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    wanted to know how much HP and twq will pi heads give and will nopi heads be worth porting?
     
  6. Dalamar

    Dalamar Post Whore Retired Staff SN95 Supporter

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  7. BOOSTED98GT

    BOOSTED98GT New Member

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    I've heard from a few sources that some porters (Renegade/Steen) are able to get some pretty good flow #'s out of the NPI, so good that they are actually comparable to PI's.
     
  8. DropTopPony

    DropTopPony Administrator Staff Member Admin SN95 Supporter

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    Renegade ported NPI's are great heads! I have seen a few Jim ported and i even tried to swap my VT st2 PI's for a set. Some people just believe the NPI's are junk because thats what we were told back in 96-98 before the better intake(pi) came out. People were porting NPI and then putting the stock NPI cams/intake back on them and not gaining much...but now we know that the intake and cams were the major difference and P&P'd NPI's flow quite well
     
  9. Dalamar

    Dalamar Post Whore Retired Staff SN95 Supporter

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    How much do the ported NPI's cost?

    What power numbers are they getting from them?
    :)
     
  10. blackfang

    blackfang Active Member

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    Your welcome.
     
  11. 1996mustangGT

    1996mustangGT Well-Known Member

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    so then when will you get to the limit of the non-PI heads?
    if your gonna have to change them to PI somewhere down the line
    because they can flow better after porting then why not get them now, and
    lower the compression ration? by the way, how do you lower the compression?
     
  12. blackfang

    blackfang Active Member

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    JL is running low 12's on motor with his ported NPI's. Once you start getting into some serious hp and changing the purpose of that motor aka race applications, then you can switch to PI heads. Also whether staying NA or FI will dictate too.

    As for lowering CR, the piston choice, and design does that along with heads.
     
  13. 1996mustangGT

    1996mustangGT Well-Known Member

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    so eventually i plan on turbo(s) possibly,
    would it be better just to go ahead and get the
    heads as well?
    thanks
     
  14. ALITL8

    ALITL8 Well-Known Member

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    what cams, intake and exhaust is JL running. did he build the bottom end (i.e. pistons, rods, etc)? also what kind of hp/tq is he making?
     
  15. Dalamar

    Dalamar Post Whore Retired Staff SN95 Supporter

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    Yes, that's what I want to know too.
    So NPI's can get 12's... How much money are we talking about here???
    What did they do, and how much does it cost?
    anyone know?
     
  16. whty98

    whty98 Active Member

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    I don't think you can tell if the intake is NPI or PI from the top, except maybe the alternator bracket, but that can be changed around. It's the height of the intake that makes it NPI or PI. Taller is PI and NPI is way shorter. The PI intake should almost touch the block where the NPI should have room to put a hand in easily, I think. Correct me if I'm wrong
     
  17. DropTopPony

    DropTopPony Administrator Staff Member Admin SN95 Supporter

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    JL also runs low 12's in a Thunderbird...not a Mustang so he would probably be high 11's in a Mustang due to the several hundred pound weight savings.

    I think JL runs a SVO intake on his NPI heads, not sure of the cams.
     
  18. 1996mustangGT

    1996mustangGT Well-Known Member

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    so hes doing all this with a non pi, non forced induction
    engine....thats pretty impressive
     
  19. DropTopPony

    DropTopPony Administrator Staff Member Admin SN95 Supporter

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    yup he is NPI and no power adder...but if people would get over the PI is better then NPI thing then they would understand that when equally equipped the heads are about equal. PI heads come with larger valves and higher lift springs which give them a advantage. When you add PI valves to a NPI head it does alot in improving air flow. You can also have the spring perches macined to accept the larger PI or aftermarket high lift springs or use the Crower kit with offset retainers.
     
  20. 1996mustangGT

    1996mustangGT Well-Known Member

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    i gotta stupid question, however,
    how difficult is it to install the cams yourself?
    i really dont have the exra money,
    and after doin the intake and cam swap (pi)
    so i need to get a tune?