swapping 4.6 pi heads
Hotshot
Joined: Aug 2002
Posts: 12,679
Likes: 15
From: BC, Canada
swapping 4.6 pi heads
Hi last resort and welcome to FTE 
As far as I know the only difference between the normal heads and the Power Improvement heads are the ports. I believe that you can swap the heads and intakes and everything else will work.
As far as I know the only difference between the normal heads and the Power Improvement heads are the ports. I believe that you can swap the heads and intakes and everything else will work.
Senior User
Joined: Feb 2001
Posts: 223
Likes: 1
From: Long Island
swapping 4.6 pi heads
"Has anybody swapped pi heads on a 98 truck? Does the comp ratio raise with the swap?"
Ford changed the pistons when they switched to the "PI" heads. They changed from pistons with a 10.5cc "dish" to pistons with an 18.5cc "dish". It is assumed they did this to compensate for the higher compression ratio produced by the "PI" heads.
I don't know from personal experiance. But I've read that if you swap in the "PI" heads and leave the 10.5cc pistons the compression ratio will rise from 9:1 to about 10:1. Not a problem except maybe some pinging. If that occurs try some higher octane fuel.
Good Luck,
Bill
Ford changed the pistons when they switched to the "PI" heads. They changed from pistons with a 10.5cc "dish" to pistons with an 18.5cc "dish". It is assumed they did this to compensate for the higher compression ratio produced by the "PI" heads.
I don't know from personal experiance. But I've read that if you swap in the "PI" heads and leave the 10.5cc pistons the compression ratio will rise from 9:1 to about 10:1. Not a problem except maybe some pinging. If that occurs try some higher octane fuel.
Good Luck,
Bill
Last edited by wmcnally; Apr 7, 2003 at 10:59 PM.
