The PI Headswap and You -

Discussion in '96-04 - 2V Specific' started by Dalamar, Apr 23, 2006.

  1. Dalamar

    Dalamar Legend SN95 Supporter Retired Staff

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    Hello all SN95 owners and fans.

    I have followed a nuber of threads - on this site and other Sites about the PI headswap.
    Some say "its good" others say "too expensive" Ther seems to be a lot of hype about it,
    so I thought I'd sum up how I see it.

    I did the PI swap on my car back when it first came avaliable, and yes it was pricy then.


    I. "The Car"
    IMO the PI heads/intake is the only thing that seperated us from the newer mustangs. And We have better looks!!!
    Also, the chassis has been relatively the same since the fox body until the 04 GT.
    So all these guys that say "the 96-98 is the worst ever!!!....... you should just buy a different car." bla bla bla.
    If that's they're opinion, they're welcome to it - but I prefer to look at the whole picture.


    Here's a basic rule I consider when looking at upgrading parts.
    If the new part doesn't remove a resitriction in your engines air-flow, you will gain no power.

    The PI heads are a big restriction if you want more power - ie. more air-flow.
    they have decient low end and some torque to get you going, but at about 4800 rpm they fall on they're face.
    BC, the airflow is maxed!

    To increase power on these cars there are a number of bolt on's avaliable.
    I have done most of them and only recommend gears, CAI, and Exhaust (mufflers)
    Gears- you really feel the difference,
    CAI- is relatively inexpensive, and you can feel a little difference, though some brands are crap.
    Exhaust- it's all about the sound, minor power gain.
    hedders are cool, but dont give you much, if any power unless you add a blower. KB doesn't even recommend them for they're kits.

    Most bolt-on's dont give you much of a power gain to be worth the cost, I say save it for a blower or, in our case
    PI "stuff" and/or blower.



    II. " The PI"
    So, on the PI note -
    There's basically 3 options to gain power...

    1a- PI intake swap without adaptor kit - gains 18 rwhp NA. (naturally asperated)

    To do this, you will need the following parts:
    XW7Z-9439-AA intake gskt $6.08 ea
    F8AZ-10153-EA alt brkt $10.53
    XR3Z-18B402-AA coolant tube $19.67
    F1VY-8255-A thermstat housing o-ring $3.83
    F1VY-8507-A water pump o-ring $2.43
    XR3Z-9L437-BA upper plenum o-ring $3.05
    F75Z-8555-AA coolant tube nipple $5.73

    1b- PI intake swap with adaptor kit - couldnt find dyno results but I'm sure it's a little more power because there's no
    step inside the runner where it meets the head - resistance.
    Livernois has a kit with the adapter plates and all the parts, or you can just get the intake.

    Here's a good thread on the swap: http://www.redpulsar.us/~coldfusion/intakeswap.html


    2- PI intake and custom cams -
    You can get a decient power gain from this, there are a few different cams for NPI heads, NA or supercharged.
    You're looking at around 40 HP gain here.
    VTengines.com has some good cams for this.
    but remember - this is the limit you can gain, your increasing the volume of air the cylinder can take by using the cam,
    gaining a little extra flow with the intake, but are limited by the size of the intake ports, and valve stroke.


    3- The PI Swap - consisting of the PI heads and intake, and all the gaskets, head changing kit ect.

    Gains 60 HP straight swap.

    Gain - 100-120 rwhp (supercharged - meaning on a car that was alread supercharged, not the heads and blower gains added together)

    Gains 80-130 rwhp ported with cams, naturally asperated.

    Ported Heads, Intake, cams and blowers... all you could use.
    A guy at THP I spoke to got 780 rwhp with ported PI, cams, forged bottom, and turbos.
    and alot of tuning... :) all out of his "crappy" little 2V.

    Other examples:
    I can't find the link, but on corral there is a long thread I was involved in, a guy on there was in the same boat, my cousin is in - had a vortec wanted more power, did the PI headswap, kept same boost, all that - gained 110 rwhp.
    So supercharged, he gained over 100 HP by only changeing the heads and intake. He did no porting or cams. (that I remeber)
    That's impressive.

    As I mentioned in other posts, I've talked to a number of guys that got 130+ rwhp with ported PI's, custom cam, and a good tune.
    This also leaves you potention to increase power in the future if you want more.
    This is where I am with my car.
    I gained 95 rwhp, with a so-so tune, and at 4800 ft. elevation 5 years ago when I did mine. Automatic trans also.
    Got my stuff here: http://www.powerheads.com/headswap.html
    Next is forged rotating assembly and blowers.

    Let's not forget that the mighty 5.0 is a 2 V. with 1 cam, and can get awsome power. Are there different heads avaliable for that?...


    III. "The Rest"
    Once you get here you have to look at the rest of the drivetrain.
    Our rods are limited at approximately 450 rwhp - after that your chances of sneezing one out of the block are good.
    Forged rods, pistons and Crank are recommended.
    After that your transmission will blow up, and axles can go if you push over 500 rwhp.

    Another thing I see is people say the compression will go up......
    So what. the modular loves high compression. and if you're adding a blower, that's what your doing anyway.

    If you go custom cam or porting you will need a tune. I recommend finding a very experieced tuner. It makes a big difference.
    Detonation is the main cause of a blown engine.
    the main cause for detonation is a bad tune.



    Money is the big factor with the Swap.
    Until reciently it was about $3000 or more depending on what you wanted in way of porting, valves and cams.
    The labor involved can also add up if you're paying someone to do it.

    When I found this, I was impressed.
    http://cgi.ebay.com/ebaymotors/1996...emQQcategoryZ33617QQitemZ8058206811QQtcZphoto
    This is what my cousin is doing for his 98 - already has a vortec.
    I'll post up his results....

    1350 for everything, WOW.
    1595 at powerheads.


    As some have stated, you can find used PI heads, for even less.

    So, to sum it up:
    If you want between 250-350 hp, a blower and bolt on's will do you.
    (Or the PI swap and good cams.)

    If you want more than 400 - the PI is a must.
    It's the place to start for serious HP gains.

    Best wishes to all, and don't underestimate the potential of our cars!
     
    RockstarMentality likes this.
  2. 97vertstang

    97vertstang Well-Known Member

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    wow!!!! great write up and answer lot of my questions!! :thumb:
     
  3. 281powered

    281powered Member

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    ya! good stuff, i like that :dancing6:
     
  4. ALITL8

    ALITL8 Well-Known Member

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    great write up Dalamar.

    i dont know if its true or not but if all youre planning on doing is the PI swap and bolt ons (i.e. CAI, headers/exhaust, gears, etc.), the heads only add another 10 or so hp over the cam swap in the NPI heads? budget wise i can probably get a PI intake and the cams swapped out for close to $1350 parts and installation. ive got $175 in my NIB PI intake and im looking to spend $100-$125 for some PI cams. if i pay a mechanic to do the install, i'll spend $1000-$1500 to get it done. if me and a buddy do it over the weekend i'll spend a couple of hundred bucks + some cold beer/pizza.

    IMO, on a budget, the PI intake and cam swap is far more affordable than the full PI swap even if you do some port work on the heads. ported NPI heads, if im not mistaken, will flow better than non ported PI's.

    full PI swap, non ported = PI intake/cams swap, ported NPI heads... give or take a few hundred dollars

    edit: forgot all about blowers... those are expensive!
     
  5. Lightning Struck

    Lightning Struck Legend

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    great info, just one final thought if you want kick ass performance drop that sohc and get a 4 valve 8)
     
  6. caseypayne69

    caseypayne69 Active Member

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    I'm saving for a PI headswap and its not looking cheap here.  I got used heads and intake off a 01 GT for 350 bucks.  I would like forged internals, and possible a big-bore setup.  Thats talkin 4,000 easy.  I also want my heads ported with a com cam, probably 270.  Thats 2,000 dollars.  So 2,000 for heads 4,000 for big-bore block then probably having someone else put it togather probably another 2,000.  I'm looking at 8,000 dollars for 430 ish hp.  Not seaming worth it right now. The reason my seams stepp is because I figure when I do the swap. If i do. I'm going to do it right the first time.
     
  7. Blueoval

    Blueoval New Member

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    Really nice write up however I am not sure that I totally agree with it. The stock non-PI heads with a PI intake and my SHM 2730 cams which are only 500 lift on intake and exhaust and a well worn out 148K mile shortblock yielded 243 rwhp on my car and that is with a untouched motor and a few bolt-on's. With my car burning as much oil as it is I can almost guarantee that I am not getting the full compression that I am suppose to be getting. That is why I am looking at a rebuild at the moment. With the setup that I am going with I will be doing the motor build cheaper then I can do a headswap and will end up with 10.46:1 compression with non-PI heads that I am going to port myself probably to keep the costs down and should yield around 300 rwhp Naturally Aspirated. With that compression it should be a lot of fun on a safely setup 75-100 shot later, but mainly I am building it for a good running NA motor. JMHO!
     
  8. ALITL8

    ALITL8 Well-Known Member

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    friggin cobra guys!!! :gtfo:









    j/k
     
  9. Dalamar

    Dalamar Legend SN95 Supporter Retired Staff

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    Thanks, Alitl8
    It's true, power costs money.

    It depends on how mych power you want to get overall...

    If you're doing the pi intake and cams, I wouldn't do the PI cam, I'd get a custom cam.
    There are some good grinds out there for NPI, NA.
    Crower stage 2 is good, there are others. so, if you're going that rought, i'd pay a few hundered extra and really gain from the cam.

    You'll also need a tune.
    If youre adding a blower later, get a supercharged grind.



    I'm not sure what you're asking about being about 10 hp more than a PI. How much do you expect to get from the intake and PI cam?

    Good luck with your mods.
     
  10. Dalamar

    Dalamar Legend SN95 Supporter Retired Staff

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    I hear you on that one.
    It does add up fast.

    Big bore is the way to go. I'm doing that with my shortblock.

    How much power are you planning on running?
    Are you adding a blower.?
     
  11. Dalamar

    Dalamar Legend SN95 Supporter Retired Staff

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    Sounds like you've had some fun with your car.

    so, you gained about 60 HP.
    I stated approx 40 HP, and you got some from your tune, and bolt ons.
    So 40-50 for the intake/cam and some from the tune and bolt ons. hard to say exactly how much from which mod.
    Doesn't that add up?


    I'm not slamming anyone who doesn't do the PI, I just try to look at realistic numbers.


    What are you looking at doing with your engine rebuild?
    Definately post up your results!
     
  12. Dalamar

    Dalamar Legend SN95 Supporter Retired Staff

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    Thanks Snakebit.
    I figured you'd pipe up in here.

    So, just out of curiousity, how much difference did you pay from selling your 98, and buying the one you have?
    and how much power are you putting down?
     
  13. Adam

    Adam Member

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    Nice write up. i can tell you from personal experience that I did the headswap, put in VT Stage 1's, and gained 72rwhp. Thats blower country. I paid $500 for my heads/intake shipped to me. I paid $600 for my cams. Thats $1100. I sold the stock PI's for $150 so i had about $950 invested to gain 72rwhp.
    Blueoval, I think you have a task ahead of you. You may have put down 243rwhp but I can tell you that you have a very small powerband compared to my car. And you car is a stick too, thats a big difference. Like at least 20rwhp. You can go the NPI route, and I think you may accomplish what you want in time, but honestly I don't see what it will prove. But like I said before, best of luck to you. BTW Dalamar, I got the package in the mail..thanks man. Car is back to stock front suspension and rides like a Caddy!! 8)

    Adam
     
  14. ALITL8

    ALITL8 Well-Known Member

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    i expect to get about 40hp +/- from the intake and cams, with a dyno tune probably more. the main thing im looking at is stretching out my torque curve, better flow. on the question/statement, ive been told that stock PI intake/head swap compared to PI intake/PI cams swap only yields about 10 more hp.
     
  15. Dalamar

    Dalamar Legend SN95 Supporter Retired Staff

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    I doubt you'd get 40 with stock pi cams.
    If you do - great.
    Dont know for sure, havent seen any feedback on that specifically.

    The PI headswap is 60 rwhp. Powerheads states 65 rwhp.
    If you get say 30, the headswap is double that, and gives you much more potential for added power in the future.
    NPI heads You'll be limited for increasing power later, Just fyi. not trying to be negative, I've just seen it before.
    Do you have the PI cams yet?

    What are your plans for the car after you do this?
     
  16. Blueoval

    Blueoval New Member

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    When I dyno'd my car after I first bought it with just flows on it, the car put down 201 rwhp and that was at 75K miles. I have had many conversations with JL on the phone about setups for my car. We have worked out the details on the setup that I am going to go with. Also we have talked about with the SHM cams that I am running that I am not seeing the full potential of my cams with the PI intake, however that will be changing soon enough. ;) Here are the specs of what I am going with:

    Link

    Adam, with my cams and the PI intake my car does not start dropping power until 5650-5700 with a stock untouched shortblock & stock untouched non-PI heads. Basically I am not trying to prove that the non-PI heads are worth keeping, Johnny has already done that. What I am trying to show is that you can get 300 rwhp out of non-PI heads with the same compression and ported non-PI heads that you would factor most headswapped cars having. I just can't justify the PI headswap on my car because I know that the non-PI heads will get me where I want to be. JMHO!
     
  17. Lightning Struck

    Lightning Struck Legend

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    I don't want you 2valve guys taking me wrong, I have NOTHING against the GT's 2 valve motor I just know from my own experience that the performance gained by going to a 4 valve is crazy. With all that crap I had on my GT (every bolt-on on gods green earth) my cobra will walk all over it. Granted I had NON PI heads and cams but even with the new motor I was getting together I still would not have more than 300-320 at the tires and I'm around that now with my 4 valve and just exhaust. To answer your question I got 10k for the GT with the motor and I paid 13 for the Cobra. I love the modular motors but the advantages of the better flowing 4 valve heads will make your head spin. If you ever get the chance to pick up a 4valve and do a swap in your GT's DO IT, its a great custom mod and the power gain and potential from the swap is worth the money you would put into it.
     
  18. Lightning Struck

    Lightning Struck Legend

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    :rollinglaugh: :rollinglaugh: :rollinglaugh: god I use to say the same thing when I had my GT and the 03 and 04 Cobras were all around me .......... :gtfo: It drove me crazy :mad:
     
  19. Dalamar

    Dalamar Legend SN95 Supporter Retired Staff

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    Snakebit - that is a really good price for the cobra.
    For 3000 difference, I'd change to a cobra also.

    I actually looked into buying a 98 cobra instead of upgrading mine, but couldn't find
    one in as good condition as my car, plus I had ported PI's, so I looked at the cost and this works for me.
    Car paid for and all that.


    There's an interesting artical in MMFF - NA stroker 2V. with custome intalke, 440 HP NA!
    Pretty dam good. They are Fiiiiiiiiinally starting to develope our lonely 4.6 2V.
     
  20. Lightning Struck

    Lightning Struck Legend

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    I got lucky getting this one, it was SUPER CLEAN inside and out, plus it only has 50,000 miles and was all stock (other than a side exhaust kit) I feel great about how things turned out :) :). The modular cars are coming along great, it has taken a little longer than we would have liked, but the aftermarket is getting its rear in gear and putting out some good products now and the power levels of the 4.6 cars are getting higher everyday. In a few years 400hp 2valves running n/a will probally be a common thing on the street, as well as 600hp 4valves..............gotta love new technology :thumb: