The PI Headswap ---

dalamar_96

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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 lay down some facts.

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 up to 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 on your NPI heads-
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 (cam and intake)
VTengines.com has some good cams for this.
but remember - this is a limited 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 etc.

Gains 60 HP straight swap.

Gains 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 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.

The aftermarket is finally starting to develope the 2 V. and just over 10 years too!


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......aaaaaaaa noooooooo!!
So what. the modular loves high compression. and if you're adding a blower, that's what your doing
anyway. NA strokers usually run in the 12:1 compression range....

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-$5000 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 THE 2V!
 

LT1KILLER

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I spent about 800 bucks to do the swap on my 98, used parts bought off Ebay and head changing kit from Ford.
 

Naughty GT

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Just Picked Up P I Heads From A 2000 Gt With 41k On them For 400 Waiting To Get A Pi Intake And Mosers. Your Info Was Very Helpful Thx!!! :rockon:
 
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dalamar_96

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LT1Killer - thats sweet. did you get it dnyo'd? if so, how much did you gain?


Naughty - glad the info was helpfull. Good deal on the heads. Good luck with the rest, you'll like it!
 

Naughty GT

PI SWAP GEARS BOLTONS
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No not yet but once i do the swap and put the moser and get a tune will post numbers thx again!!!
 

dalamar_96

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bump, anyone else like the PI?



the 2V is underestimated, and underdeveloped.
there's an interesting article in the latest MMFF, custom built intake, 2V stroker, NA - 430 HP.

Also got feedback on a twin turbo'd, forged up 2V, ported heads, cams - 930 rwhp.
dam, thats cool.
 

LT1KILLER

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I ended up trading the car in before I was able to do the swap so no numbers, made money reselling all the parts back on ebay though.
 

Thomas_W

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I did the PI swap to my old 97 GT. You could definately feel a noticeable seat of the pants increase (i figured about 50rwhp). But before i could run the car at the track, the motor seized up. So i end'd up putting a complete 02GT motor in the car (this is back in 2002).

There was NO difference in power between the 02 gt motor and the PI swapped 97 motor. I've also got a buddy down in Orlando florida, pushing 450rwhp with NON pi heads. The non-pi heads really aren't that bad, the cams just SUCK. I had an article around here somewhere that show'd the flow numbes of ported PI and Non-PI heads, and if my memory serves me correctly, the Ported non-PI heads flow'd more in the higher lift's than the ported PI's. but i can find the article, so...
 

GR8WHITE

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PI head swap onto a 96-98 motor gains a ton of compression. Factory NON PI heads had an 11cc dish and the NON PI heads have a 51cc chamber. The PI heads have a smaller 42cc chamber And PI pistons were 17 cc dish. So putting 42cc PI heads on a 11cc NON PI bottom end nets a gain of about 1.22 compression. From stock 9.3 to 10.52


Flow numbers on stock 2V heads. Intake side

Valve Lift----------------NON PI -------------PI --------------SVO

.050 ----------------------25-----------------25----------------27
.100 ----------------------47-----------------51----------------54
.150 ----------------------64-----------------76----------------81
.200 ----------------------83-----------------102--------------106
.250 ----------------------99-----------------124--------------131
.300----------------------114-----------------138--------------155
.350----------------------125-----------------149--------------171
.400----------------------136-----------------153--------------177
.450----------------------147-----------------155--------------184
.500----------------------156-----------------156--------------193
.550----------------------163-----------------159--------------203
.600----------------------166-----------------160--------------206


Flow numbers stock heads Exhaust side

Valve Lift----------------NON PI----------------PI---------------SVO

.050-----------------------22------------------24---------------23
.100-----------------------40------------------49---------------46
.150-----------------------60------------------68---------------69
.200-----------------------80------------------84---------------90
.250-----------------------96------------------96--------------106
.300----------------------108-----------------107--------------119
.350----------------------112-----------------116--------------128
.400----------------------115-----------------123--------------134
.450----------------------116-----------------130--------------137
.500----------------------117-----------------133--------------140
.550----------------------117-----------------136--------------141
.600----------------------117-----------------138--------------143



The PI head is superior up to .500 lift where the Non PI head equals the PI head. All numbers after that for NON PI heads are pretty much academic since I have yet to see a NON PI cam with lift above .500 The other factor to consider is velocity not just pure cfm flow. The PI heads have larger cc intake and exhaust ports but still have higher velocity due to port design. The SVO heads are the best 2V heads for flow but are very costly. They are also still limited by the NON PI cam selection, so their flow #'s above .500 lift are also academic.


I have made 320-330 rwhp, depending on the dyno, with compression, cams, unported PI heads with Mod Max larger valves, Comp cams and exhaust. The potential for good NA power is there as none of this combo was unique. All of the parts were "off the shelf" items. The quest for 400rwhp now begins. :burnout:
 
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foofinator

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Sweet info.. I have a 98 GT as a DD..

So far I ordered the Livernois PI intake/adapter kit..

What more could I do for 300 RWHP?

Next I had in mind were some cams, gears, intake and exhaust.

Any advice?
 

GR8WHITE

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You could do the PI heads and intake pretty cheap. Add a set of cams and springs to go with the exhaust and that should get you close to 300RWHP after tuning.
 

dalamar_96

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Ya, I agree with greatwhite on that.

you won't see 300 with NPI heads unless you de everything else- cams, valves, orting ect ect. that's alot of cash.
PI heads are easier IMO, throw in some good cams, tune it, you're there.
with potential to grow in the future too.
 

GR8WHITE

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I think I have found a 96-98 4V motor that will be TOO tough to pass up on. At a bare minimum I will do the aluminum block. I am really considering going 4V. The 2V heads flow OK, but can not be worked enough to match the 4V untouched. I know the combo that would put 400RWHP down in NA trim, but it gets close to the edge of daily driver survivability. Big bore, stage 3 heads, flattops for an almost 13:1 compression, my cams, Fox Lake intake and other existing exhaust items. I'm positive that would be the 400 number maybe +/- a few HP, but that compression is real high for a 2v. You'd have to index the plugs and really watch the tune. You could get that number with the 324 and less compression, that's just a ton of money to spend just to say "Yeah, I made that on motor."
 

96stang

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can you have npi heads and put the pi intake manifold on? cause i need a new one and some ppl say u can and some ppl say no.. you seem to know alot about this

thank you
 

stellar591

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96stang, yes you can install the PI intake on the non-PI heads. It's described in Part II. "The PI" of dalamar 96's first post.
 

96stang

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after doing this swap i know you can put pi cams in npi heads but can you put aftermarket cams that go in npi heads into the pi's or do you have to get the cams for the pi's??
 

stellar591

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I guess you could, I dont see why not. But I dont understand why you would want to.... all the non-PI cam grinds are less aggressive than the PI cams if I remember correctly.
 

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