The tag on the valve cover says my engine was produced on 9/11/98(not sure if that's an OMEN or not), but was wondering if anyone knows when they started putting the PI heads on the 4.6L Romeo engines?

And what makes the PI heads "performance improvement"??? And can you put PI heads on if they weren't originally on the engine?????

 

I believe PI heads started in the 99 model year. I know the cams are improved and the combustion chambers i believe are smaller which would yield a higher compression ratio bolted on a non pi short block.

 

They started putting PI heads on the 5.4 in 99
Don't think the 4.6 got them until 01

Phil

 

The 01 model year 4.6 got the Pi heads. The improvement in the port design improved the flow. The Combustion chamber is smaller and the cams are different.

 

2001

 

So can you put Pi heads on a non-PI engine?

 

yup

 

It raises the compression ratio to 10.5.