STATIC COMPRESSION RATIO-5.4 SWAP?
 

Sullivan has some figures but they are strictly 4V company from what I saw but they had some charts showing what could be achieved with the heads and the common dish pistons available, interesting info!
What does the typical npi to pi swap on a 4.6 yield?

Well, I've searched enough tonight. looking for the cc's of 2V npi, pi heads. Also what flattops in a 5.4 with PI heads would yield for compression. It looks like Sullivan has the PI with our piston dish at 8.8:1 and we know ours is more like 9.4:1 so it seems with the 5.4 piston being .100" in the hole the compression with flat-tops and PI heads would NOT yield the 11.2:1 shown on the Sullivan site but maybe a half point lower, maybe more? Anyone? Still a 10.5:1 would be quite a jump from our anemic 9.4 made for the masses who wanted to own a mustang with a V8.
10:1 would have been the way to go for the GT, again, IMHO! Want 87 octane, buy a V6! 93 costs $3 more a tank, my goodness! I am concerned with mileage but not at the expense of decent performance and as sad compression makes a motor more efficient. new Vette is what, 10.7:1?
Done ranting and my apologies. When the brand of adapter plates that are considered the best cannot be found it is frustrating. Enjoy the weekend!

If you bolt up PI heads to a NPI motor you will bump your compression ratio to 10.5:1. They sell 11.5:1 pistons for the 4.6. The heads for the 4.6 and the 5.4 are the same. The bore sizes for the 4.6 and 5.4 are also the same. so they will yeild the same compression ratio. This is the compression ratio I plan on running fro my 5.4 Crown Vic.

As for the spacers, I got a good set from ADTR, a parts store for the Crown Vic's. I have no idea where he gets his stuff from but If you want to ask I can give you his E-mail. The spacers are aluminim and they macth up really good. But i'm getting the heads ported along with with Intake so the spaces have to ported as well.

Knew about the heads and the bore but if the 5.4 has the pistons sitting deeper in the bore than the 4.6 the compression would be less in the 5.4. Honestly I will call Sulivan and see what they say. I am not saying I don't believe you but would hate to end up with 11.5!! Sure a link to good adapters would be cool, post itso all can see! THX.

A STOCK PI 5.4 only has a compression ratio of 9.0:1... and flat top pistons with stock bore and gasket thickness will be at 11.01:1 for a 5.4

http://www.adtr.net/

E-mail Chirs. He doesn't have them on the site but if you Ask about them get can get them for you.

ADTRsales@hotmail.com.

Also if you own a Crown Vic check out the site. you might find something you like

GraphicNature nailed it.

Download a copy of Virtual Engine 2005 (LMK if you need a copy). There's a free download version IIRC. You can use it to calculate the CR for any combo as well as all kinds of other research.

Desktop Dyno is another great application and it works great with Desktop Drag. I have a cracked exe for Desktop Dyno so I don't need a key for either. I'll hook up those that I know well enough with info on where to find such things.

I did a NPI 5.4 (stock pistons) with PI heads and acording to the book written by SHM my CR is 9.6:1