I noticed that my '97 5.4L is listed as having 235HP, while the '99 and on 5.4s have 260HP. Anyone have a run-down of exactly what the differences are? Any updates possible?

 

HI!... The "97" - "98" 5.4's in the F-150's had non "P.I" heads (POWER IMPROVED), small profile cams, and a more restrictive intake manifold.

The "99" to current 5.4's in the F-150's have "P.I" heads which have larger intake/exhaust valves, redesigned combustion chambers, larger profile cams, and a better flowing "P.I" intake manifold.

Here's a few pics of the differences between "P.I" heads and non-"P.I" heads.

https://www.f150online.com/galleries...4-794-6999.jpg
https://www.f150online.com/galleries...4-794-7042.jpg
https://www.f150online.com/galleries...4-794-7046.jpg

 

I believe '99 was the first year for the plastic intake manifold.

 

I'm used to a 6.9diesel in my '85 F-250. Whats this about a plastic intake? Some kind of composite I hope? How have the been holding up compared to the old style?

Just wondering since i'm considering a newer 150
Thanks

 

Don't know if it's a composite, but one would assume so. As far as I know, nobody has had an intake failure. Seems to be quite durable.

 

HI!... I beleive the plastic intake manifold came out in "2001" on the 5.4's. My buddy has a "2002" and it has one. I have a "99" and it does'nt, it still has the better aluminum intake manifold. The plastic intakes are made out of ABS plastic. They are prone to cracking on the casting seems and the heli-coils strip and pull out. Forget about bolting a KENNE BELL supercharger on one. I've seen it literly get torn right of the plastic intake. Not strong enough. Plus you can extrude hone a plastic intake. Sure it's smoother inside alreay but if you install fully ported/polished heads on your 5.4, you will not be able to port mach the intake to the heads or make the intake physically flow more air.