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#1906141 - 11/09/09 09:30 PM NPI vs PI heads...
1999PI Offline
Banned
Member

Registered: 10/20/09
Posts: 405
Loc: 48021
Ok so I read things about PI heads and NPI heads...whats the difference and wouldnt a police interceptor have PI heads.If not then whats the difference. How much power would we be talking if adding PI heads.
_________________________
1999 Crown Vic Police Interceptor 90k miles

Interior Mods..Lighted window switchs on driver and passenger doors.
Fixed headlight switch lights

Exterior...Clear corners/new headlight assy's

Future..Aftermarket C/D player..dual flowmasters..honeycomb grill,chrome tips,bumper tuck,chin spoiler,paint job

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#1906188 - 11/09/09 10:28 PM Re: NPI vs PI heads... [Re: 1999PI]
Colt45 Offline
less is more�
Poobah

Registered: 08/30/04
Posts: 6447
Loc: Moses Lake, Wa
PI does not mean Police interceptor. It means Performance Improved. NPI means Non-Performance Improved. Mustangs got the PI heads, cams and intake in 1999. Panthers did not receive them until 2001. Putting them on a stock NPI engine will raise the compression ratio and require Premium gasoline. A cheaper solution that many have done is install the PI cams and intake on their stock engine. That is actually most of the HP improvement.
_________________________
-Colton


2004 Ford Crown Vic LX, 89k "Tank" (Totaled 12/06/15 22:30 PST)
2002 Ford Crown Vic PI, 201k "Highwayman" (Ex-Kootenai County, ID Unit #42) - Down for bad engine
2003 Ford Crown Vic PI, 98k "Name TBD"

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#1906357 - 11/10/09 01:28 AM Re: NPI vs PI heads... [Re: Colt45]
1999PI Offline
Banned
Member

Registered: 10/20/09
Posts: 405
Loc: 48021
 Originally Posted By: Colt45
PI does not mean Police interceptor. It means Performance Improved. NPI means Non-Performance Improved. Mustangs got the PI heads, cams and intake in 1999. Panthers did not receive them until 2001. Putting them on a stock NPI engine will raise the compression ratio and require Premium gasoline. A cheaper solution that many have done is install the PI cams and intake on their stock engine. That is actually most of the HP improvement.


I know the PI doesnt mean police interceptor...so would i have to do anything else other then add the cams and intake?
_________________________
1999 Crown Vic Police Interceptor 90k miles

Interior Mods..Lighted window switchs on driver and passenger doors.
Fixed headlight switch lights

Exterior...Clear corners/new headlight assy's

Future..Aftermarket C/D player..dual flowmasters..honeycomb grill,chrome tips,bumper tuck,chin spoiler,paint job

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#1906359 - 11/10/09 01:29 AM Re: NPI vs PI heads... [Re: 1999PI]
Colt45 Offline
less is more�
Poobah

Registered: 08/30/04
Posts: 6447
Loc: Moses Lake, Wa
Not really. A tune would optimize performance, though.
_________________________
-Colton


2004 Ford Crown Vic LX, 89k "Tank" (Totaled 12/06/15 22:30 PST)
2002 Ford Crown Vic PI, 201k "Highwayman" (Ex-Kootenai County, ID Unit #42) - Down for bad engine
2003 Ford Crown Vic PI, 98k "Name TBD"

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#1907334 - 11/11/09 02:04 AM Re: NPI vs PI heads... [Re: 1999PI]
mustang_zulu Offline
I am not
Over the Hill

Registered: 04/16/08
Posts: 1899
Loc: Garland, TX
 Originally Posted By: richardpeck


I know the PI doesnt mean police interceptor...so would i have to do anything else other then add the cams and intake?


depends... what year, make and model do you have?? i'm almost certin 96+ ur ok. 96-98 mustang guys do this mod daily. i did the pi intake and cams. it was well worth it. i found used stuff, and total parts cost was under $200. i had to buy a bunch of tools to make it all happen (needed them anyway kind of thing).
_________________________

http://www.supermotors.net/vehicles/registry/19076
http://www.kiaboard.com/1998CVHPP/phpslideshow.php
1998 CVHPP P74, 130k Orginal Miles, Flow Master Delta 40's/ CAI/ P71 PCM, P&P Inc. plenum & 75mm TB/ PI Intake & Cams/ 24 lb Injectors/ Steeda UD's

Vortech S/C Vic under construction **stay tuned**

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#1914179 - 11/18/09 06:03 PM Re: NPI vs PI heads... [Re: mustang_zulu]
Merque Offline
Climber

Registered: 06/22/06
Posts: 671
Loc: Indiana
so basically PI cams and PI intake manifold= PI engine? then whats the point of it having a higher compression? exactly how much power difference is there with the cams and intake vs the complete pi engine? does the PI ECU add anything or would a tuner be sufficient?
_________________________
2000 baby blue Mercury GS (M74) 249k miles.

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#1914200 - 11/18/09 06:35 PM Re: NPI vs PI heads... [Re: Merque]
CameronVic Offline
Coolest guy on CVN
Poobah

Registered: 03/25/09
Posts: 5345
Loc: In the beams!
What makes a PI engine a PI engine is The PI Intake, Cams, and heads. Also, they have dished piston heads. The NPI engine doesn't have dished pistons.

Therefore, if you put the PI heads on the NPI motor,(non dished piston heads) it bumps the compression by making the combustion chamber smaller. Higher compression = higher cylinder pressure, and that in turns makes more power. One would have to put a higher octane fuel in though. At least 91, but some say 93. A tune wouldn't be required, but it would be suggested.

An NPI engine with PI cams, intake, and heads would out perform a stock PI engine. It would do that because the previously meantioned higher compression. But putting any sort of forced induction on the NPI motor with all the PI stuff would be out of the question. The Rods would tunnel their way out of the block, or you'd start blowing head gaskets.... or both, at the same time. Double FAIL!!!
_________________________
1999 P71, Chevy 6.0, billet 85mm turbo, 4L80e, 3.73s, E85, etc. [email protected]
2006 P71, bone stock sans JMOD
2000 P71, Black and white
2002 LX sport

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#1914329 - 11/18/09 08:48 PM Re: NPI vs PI heads... [Re: CameronVic]
Over2tonsofFun Offline

Climber

Registered: 12/05/00
Posts: 843
Loc: Laramie WY
So would adding forced induction on a NPI with the PI cams and Intake be good?

Tim
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84 Lincoln Towncar signature field find.
89 Lincoln Town Car RIP


---IF Sh!t floats Why do chevys sink------

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#1914354 - 11/18/09 09:29 PM Re: NPI vs PI heads... [Re: Over2tonsofFun]
Colt45 Offline
less is more�
Poobah

Registered: 08/30/04
Posts: 6447
Loc: Moses Lake, Wa
Yes, thats doable, just be aware the stock pistons and rods are not designed for that service.
_________________________
-Colton


2004 Ford Crown Vic LX, 89k "Tank" (Totaled 12/06/15 22:30 PST)
2002 Ford Crown Vic PI, 201k "Highwayman" (Ex-Kootenai County, ID Unit #42) - Down for bad engine
2003 Ford Crown Vic PI, 98k "Name TBD"

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#1914472 - 11/18/09 11:07 PM Re: NPI vs PI heads... [Re: 1999PI]
Quickvic30 Offline
Just watchin
Grand Poobah

Registered: 02/24/05
Posts: 10922
Loc: Minneapolis, MN
NPI pistons still have a dish in the pston its just not as big of a dish as the pi pistons. The npi have a bigger combustion chamber on the heads and the pi's have the smaller combustion chamber and thats where the compression bump comes from the shallow dish npi piston and the smaller combustion chamber on the pi heads. \:\)
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#1914560 - 11/19/09 12:25 AM Re: NPI vs PI heads... [Re: Over2tonsofFun]
CameronVic Offline
Coolest guy on CVN
Poobah

Registered: 03/25/09
Posts: 5345
Loc: In the beams!
 Originally Posted By: Over2tonsofFun
So would adding forced induction on a NPI with the PI cams and Intake be good?

Tim
You can do that, but putting stock parts on a car is only gonna get you so far. If you bit and piece and engine together without a plan, you probably won't get as far as you would if you knew exactly what you wanted from the start. You get what you paid for. Aftermarket, when done right is way more worth it than making a frankenstine motor from stock parts with a blower on it.
_________________________
1999 P71, Chevy 6.0, billet 85mm turbo, 4L80e, 3.73s, E85, etc. [email protected]
2006 P71, bone stock sans JMOD
2000 P71, Black and white
2002 LX sport

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#1914657 - 11/19/09 04:09 AM Re: NPI vs PI heads... [Re: CameronVic]
Street_Shark Offline
Over the Hill

Registered: 05/27/09
Posts: 4101
Loc: Rain City
how much does it cost to get a good set of rods and pistons, without install lol
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#1914668 - 11/19/09 05:14 AM Re: NPI vs PI heads... [Re: Street_Shark]
wolfallday973 Offline
Climber

Registered: 01/23/09
Posts: 665
Loc: paterson,nj
to get a forged rotating assembly for the mod motor is about $1800-2300.
_________________________
1986 Crown Victoria LTD - R.I.P. 10/06/2010
1998 Grand Marquis GS Palm Beach - Cop Chip
2000 Grand Marquis LS - pretty much stock
2000 Chevy Malibu LS - P.O.S. Civic Burner

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