4.6 Engine Questions
Thread Starter
|
Freshman User
Joined: Jan 2004
Posts: 37
Likes: 0
From: Newport News, VA
4.6 Engine Questions
I have a 2004 Ford Heritage with the 4.6. What are the stock cam specs? My other question concerns the cylinder heads. Are the cylinder heads PI or non-PI. Thanks for your help.
Postmaster
Joined: Oct 2006
Posts: 4,171
Likes: 12
From: SE Texas
Originally Posted by zman764
Can some one educate me on the difference between the PI and non PI heads and while they are at it what PI means?
Thanks
Zach
Thanks
Zach
PI is know as "power improved" or performance improved". In all honesty-the head castings themselves are almost equivalent for flow and performance when equally equipped for cams and intakes. The short side radius and the shape of the intake ports on the PI are terrible for flow,and the runner size is a bit large with very little taper,and this hurts high lift flow and velocity. The NPI port is much better for a N/A application due to this-when SC'd they're the same since you're introducing cylinder fill via positive pressure. PI's are slightly better on the exhaust side due to the port change and are slightly better than the NPI when used in a SC'd application.
Basically-either head is good-you just need to make a choice on which one you want,and work with it from there. IMO-I'd use a PI head for a SC applcation,and a NPI for a N/A application.
JL
Laughing Gas
Joined: Nov 2003
Posts: 794
Likes: 3
Thanks for that clarification I have been seein that term in these threads for along time and now I know.
Basically when they started using PI heads they improved the exhaust flow and changed the cam to get more power?
And a naturally aspirated engine runs better with the non PI heads. And a turbo or supercharged engine would be more suited to the PI heads.
In lamens terms just to make sure I got the jist of what you were saying.
Basically when they started using PI heads they improved the exhaust flow and changed the cam to get more power?
And a naturally aspirated engine runs better with the non PI heads. And a turbo or supercharged engine would be more suited to the PI heads.
In lamens terms just to make sure I got the jist of what you were saying.
Postmaster
Joined: Oct 2006
Posts: 4,171
Likes: 12
From: SE Texas
Originally Posted by zman764
Thanks for that clarification I have been seein that term in these threads for along time and now I know.
Basically when they started using PI heads they improved the exhaust flow and changed the cam to get more power?
And a naturally aspirated engine runs better with the non PI heads. And a turbo or supercharged engine would be more suited to the PI heads.
In lamens terms just to make sure I got the jist of what you were saying.
Basically when they started using PI heads they improved the exhaust flow and changed the cam to get more power?
And a naturally aspirated engine runs better with the non PI heads. And a turbo or supercharged engine would be more suited to the PI heads.
In lamens terms just to make sure I got the jist of what you were saying.
N/A-NPI
SC-PI
If you want to do some reading on this to back up my claims,read the following thread and the threads linked in it:
http://forums.modulardepot.com/4-6l-...-npi-data.html
JL
Trending Topics
Thread Starter
|
Freshman User
Joined: Jan 2004
Posts: 37
Likes: 0
From: Newport News, VA
4.6 Engine Questions
I appreciate the feedback. If you replaced the stock PI heads with ported and polished heads and a more aggresive cam, what kind of HP and torque increases can you expect to see? I'm debating on whether to bolt on a supercharger or stay N/A. Thanks in advance.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Postmaster
Joined: Oct 2006
Posts: 4,171
Likes: 12
From: SE Texas
Originally Posted by My98FordF150
I appreciate the feedback. If you replaced the stock PI heads with ported and polished heads and a more aggresive cam, what kind of HP and torque increases can you expect to see? I'm debating on whether to bolt on a supercharger or stay N/A. Thanks in advance.
JL
Postmaster
Joined: Oct 2006
Posts: 4,171
Likes: 12
From: SE Texas
Originally Posted by My98FordF150
What is a good solution for the restrictive intake?
JL
