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I own a '95 T-Bird 4.6 and I have some questions about the PI head/intake swap.

1. Are 99-04 Mustangs the only source of PI heads?

2. Does mounting PI heads to the Romeo 4.6 that all MN12s use (apparently) require any modifications to the block beyond small things like new head studs?

I read some of the tech articles but I didn't find the answers I wanted.
 

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I own a '95 T-Bird 4.6 and I have some questions about the PI head/intake swap.

1. Are 99-04 Mustangs the only source of PI heads?

2. Does mounting PI heads to the Romeo 4.6 that all MN12s use (apparently) require any modifications to the block beyond small things like new head studs?

I read some of the tech articles but I didn't find the answers I wanted.
99-04 Mustangs were the "first" to get them, but they are pretty much universal on 4.6 car motors from 2002 on. My 2002 Crown Victoria has PI heads. They all have the same cams, and are universal, only difference is in the tune and exhaust for horsepower ratings.

Not sure about the truck 4.6 engines as far as PI heads. Fairly certain the Explorer 4.6's with the WAP block are PI though. Swapping one of them in gets you most of the benefits of the PI swap but with a lower compression ratio, but 80lbs off the front end, so it's essentially a wash.
 

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Discussion Starter #3
99-04 Mustangs were the "first" to get them, but they are pretty much universal on 4.6 car motors from 2002 on. My 2002 Crown Victoria has PI heads. They all have the same cams, and are universal, only difference is in the tune and exhaust for horsepower ratings.

Not sure about the truck 4.6 engines as far as PI heads. Fairly certain the Explorer 4.6's with the WAP block are PI though. Swapping one of them in gets you most of the benefits of the PI swap but with a lower compression ratio, but 80lbs off the front end, so it's essentially a wash.
One of the tech articles mentioned some 5.4s having PI heads that fit, but I don't know if that's true and, if it is, which 5.4 engines to look for.

Thanks for the answers though.
 

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Anything 2002 and up for sure and F150s from 99 and up. If they're from a 99-mid 01Mustang or truck(which would be a 5.4) you'll need the valve covers too. PI engines are more common now than npi
 

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Anything 2002 and up for sure and F150s from 99 and up. If they're from a 99-mid 01Mustang or truck(which would be a 5.4) you'll need the valve covers too. PI engines are more common now than npi
Good to know. Yeah, I would definitely take the valve covers too no matter what I pull.
 

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I own a '95 T-Bird 4.6 and I have some questions about the PI head/intake swap.

1. Are 99-04 Mustangs the only source of PI heads?

2. Does mounting PI heads to the Romeo 4.6 that all MN12s use (apparently) require any modifications to the block beyond small things like new head studs?

I read some of the tech articles but I didn't find the answers I wanted.
1) No, and there are 2 breeds of PI heads, Romeo and Windsor.

2) Depending on the year and type Romeo or Windsor the bolts for the timing cover to head may need to be changed and the cover to cylinder head holes may need to be drilled larger. Not always necessary, but sometimes required. Windsor heads require windsor valve covers. Also "head studs" are not required and as far as I'm aware it's not possible to remove a cylinder head in car on a 4.6 that has been swapped to head studs instead of head bolts. Head bolts however are a one time use according to many reputable sources (and reusable up to 3 times according to others) the factory head bolts are TTY (torque to yield) which requires a stretching process during installation. I refuse to do the job unless the head bolts get replaced with new head bolts or head studs. Head studs however can be reused many times. The heater tube in the valley of the 4.6 needs to be changed to fit the PI intake, which also requires a different nipple for it to connect to the block which goes in through the hole behind the water pump. The water pump o-ring will need to be changed at minimum due to removal for the water tube nipple change, many opt to replace the wateropump at that time.
 

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FWIW, PI heads have a larger port primarily to aid breathing on the 5.4 engines. When ported [properly], the smaller npi port actually is better for port velocity, cylinder filling and power/torque production as a whole on the 4.6 than the larger PI port.

The only advantages the PI heads present are that they have a smaller combustion chamber producing higher compression worth ~10HP on npi pisoned engines, and the intake ports are a direct match for the PI manifold, negating the need to RTV the coolant ports for a PI intake swap.
 

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Stock for stock, the extra compression you get with PI heads will be better. Once you start getting into ported heads territory, then the lines get more blurry.
 

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Just curious to what's involved with putting PI heads on a Mark 8 block? Tried to do a search because I thought there was some threads on this topic but I must be using the wrong search terms.
 

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Physically you need to drill a hole in on the block deck for proper coolant flow through the 2V heads and you'll need to use a 94/5 timing cover. I think you'll also have to swap timing guide pivots too.

You'll need cams if you plan to run pump gas though, the high compression and low overlap of PI cams require race fuel or E85
 

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Discussion Starter #13
1) No, and there are 2 breeds of PI heads, Romeo and Windsor.

2) Depending on the year and type Romeo or Windsor the bolts for the timing cover to head may need to be changed and the cover to cylinder head holes may need to be drilled larger. Not always necessary, but sometimes required. Windsor heads require windsor valve covers. Also "head studs" are not required and as far as I'm aware it's not possible to remove a cylinder head in car on a 4.6 that has been swapped to head studs instead of head bolts. Head bolts however are a one time use according to many reputable sources (and reusable up to 3 times according to others) the factory head bolts are TTY (torque to yield) which requires a stretching process during installation. I refuse to do the job unless the head bolts get replaced with new head bolts or head studs. Head studs however can be reused many times. The heater tube in the valley of the 4.6 needs to be changed to fit the PI intake, which also requires a different nipple for it to connect to the block which goes in through the hole behind the water pump. The water pump o-ring will need to be changed at minimum due to removal for the water tube nipple change, many opt to replace the wateropump at that time.
Wait, there are Romeo PI heads? I thought all PIs were Windsors.
 

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in 2000, when the tech article was written, that was true but Romeo has been producing PI heads for all the car lines since 2001. Npis haven't been in production for 12 years
 

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Hay xr-7 the only drilling I had to do is on one of the bolt holes on the timing cover.

What part of the block deck are you talking about to drill in to??

I didn't do that on my 94 other than the cover
 

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Discussion Starter #16
in 2000, when the tech article was written, that was true but Romeo has been producing PI heads for all the car lines since 2001. Npis haven't been in production for 12 years
How do I identify a car as having a Romeo built engine?

I know I could do it from the VIN, but I'd have to know what to look for.

I would assume it's not the same for every Ford vehicle, on MN12s I think it's the...sixth character?
 

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Hay xr-7 the only drilling I had to do is on one of the bolt holes on the timing cover.

What part of the block deck are you talking about to drill in to??

I didn't do that on my 94 other than the cover
he's talking about the Mark VIII engine block.
 

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How do I identify a car as having a Romeo built engine?

I know I could do it from the VIN, but I'd have to know what to look for.

I would assume it's not the same for every Ford vehicle, on MN12s I think it's the...sixth character?
I have a feeling you're going to need THIS. Might as well get started.
 

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I have a feeling you're going to need THIS. Might as well get started.
Fixed that link for you, GM. :)

"We have all the files you could look thru..."

<iframe width="560" height="315" src="//www.youtube.com/embed/pRJp5mNUA2c" frameborder="0" allowfullscreen></iframe>

j/k
 

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Grog6 that's was so

sorry when I was typing I couldn't stop laughing about that animation and the dialog.

was funny as well.

thank you Gm when I was reading the posts it kind of seemed like it was seaming together and it felt like I got slaped on the back of the head and wanted to ask.
 
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