PI or Non PI - Intake & Heads.

[Interceptor]

PI vs Non-PI intake & Heads

Starting in the 2001 model year, crown victoria's received PI "Performance Improved" ports on the intake manifold and cylinder head. These flow a little better than the NPI "Teardrop" ports used in the 2000 and earlier crownvic's Do note the acronyms used here:
PI = "Performance Improved"
NPI = "Non- Performance Improved"

PI does NOT equate to police interceptor in this context.

On the LEFT is a PI intake manifold for 01-02 crownvic's On the RIGHT is an NPI intake manifold for 96-00 crownvic's.




The easiest way to tell if you have a PI Intake and Heads is look at your Intake.... On the non pi manifold the front intake runner runs to the the passenger side. On the pi manifolds the front intake runs to the driver side. By front I mean closest to the front of the car. The pi manifold is also taller.

Non-PI on the Left - PI on the Right
(ignore the aluminum crossover, that is NOT a tell-tail sign)




Here is a closeup of the NPI teardrop ports that you'll find on 96-00 crownvics



And a closeup of the PI ports that you'll find on 2001 and later crownvics.




On the left is a cylinder head from an NPI engine. On the right is one from a PI engine.




Some crownvic owners have found that they can use a 2001+ intake manifold on their 1996-2000 vehicles if they swap in the later style heater core return tube and apply some rtv around the seal port surfaces. This is reported to increase airflow & horsepower to some extent. But be warned that some crownvic owners have ended up with difficult to diagnose drive-ability problems after this swap too.

So.... it is possible to swap in PI Heads and a PI Intake in to a Non-PI block.

[BigRed]

Not wanting to make waves, being a NOB, but according to 3 sorces, the local Ford dealer, a friend that is a Ford cert. Mechanic and a book called Performance Building the 4.6 and 5.4, the NPI ran from. 92-98. The PI ran from 99+. The PI manifold with the aluminum water cross over was made to fix a cracking problem in the cross over. The PI intake avalibale from Ford Perf. is the same one that Ford released to fix the problem, I've seen quite a few in the bone yard. To use the PI intake on a 98 and down 4.6, you have to also use the PI cylinder heads because of the port miss match. Using the PI heads and intake will jump you from 215hp to 260hp due to a rise in compression 9.7 and having bigger exuahst valves.(pardon any spelling errors, I don't have spell check on my phone)

If my info is incorrect, let me know.

[Sgt]

The plastic intake manifolds never works too well especially if you are running at high rpms all the time or have a heavy foot. I also have noticed that if you are running a cold air intake with a low temp thermostat, the manifold tends to crack as well.

[BigRed]

I was incorrect. My two human sorces thought I was asking about Mustangs, when I was asking about the PI heads. The CV's did not get the PI heads till 2001. Also after doing the math, the non-PI engine with PI heads would have just about 10.5:1 compression with the PI heads installed.

[Mercracer]

Using the PI heads and intake will jump you from 215hp to 260hp due to a rise in compression 9.7 and having bigger exuahst valves
If my info is incorrect, let me know.

You will not get a jump to 260HP on a NPI Crown Vic engine simply by swapping the heads and intake for PI pieces.

[Sgt]

I keep reading all these post saying non PI engines. If you have a P71, wouldn't you have a p71 engine minus whatever mods the law enforcement agency took off the vehicle and flashing the computer back to civilian?

[Mercracer]

I keep reading all these post saying non PI engines. If you have a P71, wouldn't you have a p71 engine minus whatever mods the law enforcement agency took off the vehicle and flashing the computer back to civilian?

PI stands for "Performance Improved". There is zero physical difference between a P71 and a non-P71 engine (unless you count the oil cooler adapter bolted to the block). There is no such thing as a special "Police Interceptor" engine when discussing the 4.6. The last time Ford did that (had a police application specific engine) was in the mid 70s with the 460. Mustangs got the PI engine in 1999 and CV/GM got it in 2001. There is no "Cop" chip and there is no "flashing" back and forth between LEO and non-LEO. The PCM is calibrated along with the transmission based on original application and there are no changes made when P71s are retired and sold on the open market.

[Sgt]

PI stands for "Performance Improved". There is zero physical difference between a P71 and a non-P71 engine. There is no such thing as a special "Police Interceptor" engine when discussing the 4.6. The last time Ford did that (had a police application specific engine) was in the mid 70s with the 460. Mustangs got the PI engine in 1999 and CV/GM got it in 2001. There is no "Cop" chip and there is no "flashing" back and forth between LEO and non-LEO. The PCM is calibrated along with the transmission based on original application and there are no changes made when P71s are retired and sold on the open market.

Thanks for clearing that up! I thought the "P.I." was for police interceptor.