97,98 vs 99& newer
 

I've read on this site regarding the "PI heads" on the 99& newer 5.4. What does the "PI" stand for, and are there any other differences which give the 99 and up there increased horsepower. Thanks guys.

Nobody?

PI = power improved

The newer heads flow better.

As for other differences, I am sure there are a few but I can't think of any major changes off the top of my head.

-Brian

Here I thought it was something technical...duh. Thanks.

In 99 or 2000 the 5.4 went to 260 hp. Before that it was 240 HP.
If this means PI or not I do no know. I do know for sure that the 97 and 98 5.4 F150's had 240 HP. My 2000 and 2002 had 260.

-jeff b.

Well, with a chip, dual exhaust, and intake, I left an 01 PI 4.6 with an intake sitting at the line. He never caught up either. Didn't impress me that much:D,,,,98

Same engine, rear gear, and bodystyle......

my 97 5.4 has 235 hp., my 2001 has the 260 pi heads. the 97 has better low end and will jump the 01 off the line everytime at 60 mph the 01 pulls even and by 80 has it by a length.
i know the never one have a different composite plastic intake.