What does PI mean?

smokin'Red35th · May 21, 2004

when talking about heads, what is PI and Non-PI??? this may be a stupid question but ive been trying to figure it out myself and have so far been unsuccessful
Thanks!

Roger_4.6_96 · May 21, 2004

Power or Performance Improved. they will give 96 - 98 mustang 40 - 60 rwhp

smokin'Red35th · May 21, 2004

so what the hell is the point of Non-PI, i have seen that come up in conversation on some threads here. Their not talking about stock cus they specified. Also, do they have that kind of improvement on a 99GT?

Roger_4.6_96 · May 21, 2004

96 - 98 had non pi wich gave them 216 - 225 bhp. then in 99 they got 265 bhp

smokin'Red35th · May 21, 2004

so do 99s have PI heads stock? if so, then to gain from aftermarket heads do you have to have them ported? I'm asking because I am planning on supercharging my car in a year or two but I want to replace the heads first, and i know next to nothing about them.

Roger_4.6_96 · May 21, 2004

right now you got the best heads on the market

smokin'Red35th · May 21, 2004

You're kidding me? so I cant upgrade them at all by porting them?

Roger_4.6_96 · May 21, 2004

ya you can port them + new cams and valves etc...

smokin'Red35th · May 21, 2004

would that be worth the time and cost of porting? do you know any approx. HP gains? Like i said, im still kind of a newbie when it comes to this stuff. Only owned the stang for a year, most of that time has been spent away from it......(again--->

)

EDIT: BTW, thanks man! Your being a huge help!

Roger_4.6_96 · May 21, 2004

im guess with it all maxed out and all bolt ons you will get 300 rwhp n/a

smokin'Red35th · May 21, 2004

so pulling the heads having them polised and ported wont do anything to make it worth the money?

Zinc03GT · May 21, 2004

Whether it's worth the money or not is up to you. Like stated before, you can definitely break 300 rwhp with a nice p&p and cam setup along with bolt-ons...a blower is cheaper and easier power, but there's something nice about a strong n/a setup

smokin'Red35th · May 21, 2004

so what kind of gains do you think i would be looking at with a port and polish of my stock heads on the 99GT? The way it was explained to me is that the stock heads are pretty much the best on the market? and the only way to increase performance is to pull them and do a port/polish. Forgive me if i understood what Roger_4.6_96 told me. Am I correct in this assumption and what kind of gains would i get with a port/polish of the stock heads?

Zinc03GT · May 21, 2004

If you did a stage 2 p&p and stage 2 cams you could see 40 rwhp with a good tune...again, it is expensive, but you'll have a nice power curve...on top of the p&p you would want to get new springs with stage 2 cams

Zinc03GT · May 21, 2004

and if you are thinking of boosting at sometime, you could go with blower cams and have a nice setup waiting for the boost...of course you'd probably want to think of getting forged internals at that point as well

smokin'Red35th · May 21, 2004

thanks! now that leads to another question that has been coming up. when i do forged internals (cuz i will be supercharging) what do i do? forged rods? pistons? crank? or all three? anything else forged???

Phoenix00GT · May 21, 2004

There are a bunch of companies out there that have internals kits. Personally I like Steeda's rotating assembly kit because of how complete it is, but there are plenty of others on the market.

Generally you want new pistons, rings, rods, studs, gaskets, bearings, oil pump, and crank. You might also want a new higher capacity better design oil pan, flywheel, and balancer.

Make sure that whatever you get will put you at the right compression ratio for the boost that you want to run.

Zinc03GT · May 21, 2004

check out www.modulardepot.com www.modularfordpowerhouse.com and modularperformance.com for some forged sets...you would want to get the whole bottom end forged

mity2 · May 21, 2004

Roger_4.6_96 said:
in 99 they got 265 bhp

260hp BTW. Off topic, but i wish there is some aftermarket heads out for 4.6... I went to yahoo, and typed Mustang 5.0 head, and I got about 100 different hit....

Zinc03GT · May 21, 2004

mity2 said:
260hp BTW. Off topic, but i wish there is some aftermarket heads out for 4.6... I went to yahoo, and typed Mustang 5.0 head, and I got about 100 different hit....

There are some heads available. You can get new heads from T&J, Patriot Performance, i believe Fox Lake and VT have heads as well. Nowhere near the selection for the 5.0, but they are slowly appearing.

What does PI mean?

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I like Pro3 and all I got was this crappy CT.

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I like Pro3 and all I got was this crappy CT.

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