Anyone can say anything they want. But I have dismantled many a motor, and this is my first time coming across this. It was a 2 valve 97-98 with 4 valve pistons in it. I know exactly what I'm looking at.
I just built a 5.4 2 valve with 3 valve pistons and PI heads with the mixing intake valve wall ported down, It runs sweet and with about 10-10.5 compression. The non PI motors have 11cc. dish pistons, PI have 18cc. dish, 3 valve 05-up motors have 6.5 cc. dish and 4 valve have a near flat top 3cc. dish.
Also the designation P71 means nothing Ford also put it on Tbirds. Not a damn difference in brakes, suspension, engine, gearing, NADA!!!NOTHING,NINGUN, JACK ****!!!

Lowflyingbird

 

Raoul- You are or they are?

 

Hey--seriously contemplating changing the heads on my '97 F-150 to the PI. With smaller piston dishes in my motor, I would assume I'm going to get higher compression? To what ratio am I going to end up with? Also considering instead maybe just saying the heck with it and replacing the long block with a newer one, say, from an '02 or '03, and just basically maybe just putting in gapless rings and possibly adding a little porting to the heads and a polish on the rods--is it worth it?

 

HIJACKER ALERT!

 

hijacker? Just saw mention of the PI heads and newer motors, and thought that it was relevant to the discussion at hand.

 

He's just being his usual ***.

 

U'r just mad, because, I beat you to it! Get back on your goat, and, leave me alone!

 

Do the PI head swap, but pull the engine to do it. This will allow you to actually see your entire engine, clean it, etc. You will see about 10:1 compression. If you are concerned about that high a number then port down the intake valve eyebrow. Thats the build up of a "wall" of aluminum by the intake valve. I did it on mine. It is to promote air fuel mixing, But I believe it's BS. All aftermarket companies remove it because it seriously hurts intake air flow. Ported down it will increase chamber volume by +2cc. Which would clear you of any issues. I'm personally running a 5.4 with 3 valve pistons -6.5 cc and PI heads with the wall ported down. I run 87 gas with no problem. While you have the motor out, check your oil pump, and install a new rear main seal.

Lowflyingbird

 

Thier may be this illusion police intercepter engines and passenger car engines with the same displacement are not identical.

What ever parts are at hand when building the engine are what is going to be used, Ford can't make money building 2 versions of the 4.6 block, but cams, and cranks, pistons ect can be interchanged.

The Crown vic is not that powerful, even in police trim, hell a Buick road master with the 5.7 ( detuned vette engine, Impalla ss ) can lay a licking as well as some of the Jap boy racer Pos.

RWD is is the only basic concept ford is still good at and the Mercury Marroder (SP) with a supercharged 4.6 was better looking than the Impalla ss, But a Camary was as quick from 0 to 60.

The crown Vic is big, cheap, body on frame, same car basic car as the town car, I still like big rwd cars.

Gm lost big time with the FWD 3.8 things with with lights and sirens on them.

 

You MAY know your engines but you just blew it with that statement above. Nothing you said there is correct....NOTHING!!
You WILL NOT find P71 in the VIN of anything except a CV Police Interceptor package. Never on a T-bird, never on a civilian CV, never! The frame, suspension, brakes, drive shaft and computer program are different from civilian CV's. The engines are the same as Granny's Crown Vic, the transmissions the same except they use a shorter tail shaft. You need to have a clue before spewing inaccurate BS. Now I wonder if you even know engines........And I can't see it takes any great skill to dismantle engines ....

Positions 5 through 7 indicate vehicle line, series and body type.

P70 — Crown Victoria (Limo/Taxi Long Wheelbase)
P71 — Crown Victoria (Police Interceptor)
P72 — Crown Victoria (Fleet Commercial)
P73 — Crown Victoria (Standard four-door)
P74 — Crown Victoria (LX four-door)
M74 — Grand Marquis (GS four-door)
M75 — Grand Marquis (LS four-door)
P62 - Thunderbird (LX)

 

a regular civilian vic probably couldnt make it 100k in police service. in a city size force they prety much run 24/7

 

Maybe it was a Friday afternoon (trying to leave the plant early) or Monday morning (hung over) build...and they line worker just grabbed the wrong parts. Stranger things have happened

 

https://www.fleet.ford.com/showroom/...cPoliceInt.asp

Here is the complete specifications of the Police Interceptor for those that are interested...

 

I didnt pull my engine when I did my PI swap...

 

My civilization vic has 1.6 million miles with its original engine. Ran 24/7 for almost 6 years as a nyc taxi then got tortured by me for the last 5 years. Maintaining a vehicle is important and I drive the proof of that to work daily. The civilian vics are just as badass as the P71 ;-)