PI Heads

Austinw

New Member
Dec 29, 2012
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South Carolina
I am about to get a 96 stang from a guy and he says he has a set on pi heads off an o2 gt that he is going to give me with the car. First question is, How do I tell if they really are pi heads? Second question is what all is involved when doing the head swap? Third and last question is, How much will I gain with the swap? HP and TQ wise.
 
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Inspect the ports. They are shaped differently. Google it for pictures.

Far as I know it's about as simple as straight head swap. You'll need the PI intake as well. PI cams if they don't come with the heads or aftermarket if you like.

You'll have a slight power increase over 99-04 GTs thanks to a minor increase in compression.
 
Inspect the ports. They are shaped differently. Google it for pictures.

Far as I know it's about as simple as straight head swap. You'll need the PI intake as well. PI cams if they don't come with the heads or aftermarket if you like.

You'll have a slight power increase over 99-04 GTs thanks to a minor increase in compression.

That's what I needed to know, Thanks man. I might as well buy cams. If im going to do all the work might as well do it the way I want it.
 
Intake ports (PI heads left.....NPI heads right)

hrdp_0804_05_z+ford_4_6_engine+pl_heads_left_pl_right_not.jpg


Stock NPI GT's will put down around 180-ish rwhp. With a full PI swap (PI heads, PI cams, PI intake) you could see around a 30-40rwhp gain. The PI heads alone are good for maybe +10-12, PI cams are good for about +15rwhp, and the PI intake usually sees about another +15rwhp give or take. Seeing as you could find these parts used for pretty darn cheap, a PI swap is one of the cheapest and best "bang-for-the-buck" mods for an NPI car.

I'm new to mustangs, so I don't know everything to do. What kind of cam's would you recommend and do I have to change any valve train?

It depends on the grind. Stage 1 cams, no matter who they are from, are usually pretty mild and don't require any valve train modifications. Stage 2 grinds are basically 50-50. Some can get by on the stock valve train, others can not. Stage 3 grinds will most likely require an upgraded valve train. The manufacturer of the cam will tell you whether any valve train mods are required. Look into Modular Headshop, HiTech Motorsports, and Comp for popular mustang cams.
 

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Intake ports (PI heads left.....NPI heads right)

hrdp_0804_05_z+ford_4_6_engine+pl_heads_left_pl_right_not.jpg


Stock NPI GT's will put down around 180-ish rwhp. With a full PI swap (PI heads, PI cams, PI intake) you could see around a 30-40rwhp gain. The PI heads alone are good for maybe +10-12, PI are good for about +15rwhp, and the PI intake usually sees about another +15rwhp give or take. Seeing as you could find these parts used for pretty darn cheap, a PI swap is one of the cheapest and best "bang-for-the-buck" mods for an NPI car.



It depends on the grind. Stage 1 cams, no matter who they are from, are usually pretty mild and don't require any valve train modifications. Stage 2 grinds are basically 50-50. Some can get by on the stock valve train, others can not. Stage 3 grinds will most likely require an upgraded valve train. The manufacturer of the cam will tell you whether any valve train mods are required. Look into Modular Headshop, HiTech Motorsports, and Comp for popular mustang cams.

Thanks for the picture and the info, Helps a lot. I will do some looking around for cams..
 

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Word of warning. Be very careful adding aggressive cams to a motor with a non-PI bottom end and PI heads.

Why?

Because the non-PI bottom end/PI heads have reduced PTV clearance. Do you homework. Consider performing a full cam degree. A clay test may also be a good idea.
 
Definitely look into Modular Head Shop cams and talk to Nick about it. I can't remember which ones, but I know he has a set that is specifically designed for the PI head swap onto the NPI bottom end.

A cammed PI headswap car will make good power and run very nicely. It will be a HUGE difference from what you have now.
 
Definitely look into Modular Head Shop cams and talk to Nick about it. I can't remember which ones, but I know he has a set that is specifically designed for the PI head swap onto the NPI bottom end.

A cammed PI headswap car will make good power and run very nicely. It will be a HUGE difference from what you have now.

Did you hear that Nick sold MHS? :O_o:
 
No, I had no idea! That blows. Almost unquestionably the most knowledgeable individual when it comes to cams on these motors.

Excessive Motorsports bought them out. They (excessive motorsports) have posted in a few of the threads dscussing Nick selling MHS and they sound like stand up guys. Nick is STILL in the shop though, porting heads and whatnot, he just handed over the business operations (sold) to EMS.

http://forums.corral.net/forums/gt-sohc/1393052-mhs-sold.html