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Discussion Starter #1
Alright, here’s the deal. I’ve got a ’96 Cat with a pooched engine…..heads and all. Now, my question is, I’ve also got a ’94 Cougar and a ’92 Grand Marquis in order to pull the engines from. The long term plan is to either pick up a set of later model non-PI heads, port them and run some style of roots blower…..or, pick up a set of PI heads and do the same thing. My question is, that with all of the subtle differences between the different years, am I going to have any problems fitting the top end to either the ’92, or ’94 blocks, or would I be better off rebuilding the ’96 mill? I don’t plan on running any more that 325hp to the wheels, but I don’t want to buy a boatload of parts and find out they’re for another engine. I read the article posted in the sticky, at the top of the forum in regards to the different engines. But It doesn’t specify what car had what engine…just the year that they came out….and even then the info is a little foggy. I have no idea if which car uses a Romeo block, which uses a Windsor block, etc? Anyone confident enough here to call themselves a 4.6 expert that can steer me in the right direction?
 

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The 96 short block is a tiny bit better for high HP building, and if the heads arent toasted those are also better for porting. The bottom ends OEM are about the same strength and the pre96 heads are junk as far as porting goes. As far as a daily driver goes, all of those are equivalent and you can mix and match whatever you need to. Any of those setups will accept a PI headswap though. If rebuilt, and of those blocks should handle 325hp no problem. 325 is a reasonable but not overboard #. They are all Romeo blocks.
 

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You will probably not be able to use the 92 engine. 91-92 were bastard years where they used the old AOD trans bolt pattern. In 93 they went to the AODE but not sure when that may have started.

The 96 would be the best of the engines you have for a build up. Good luck!:)
 

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Check the date code on the engine - 2/18/92 is the magic number. before then they were AODs, after were AODEs. Early AODEs also had the P R N OD D 1 shift pattern, so don't think that if it doesn't read PRND21 it's an AOD.
 

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Discussion Starter #5
Just double checked. The Marquis is acutally a '93 and is backed by an AOD-E...so we're good to go in that sense. What I really want to know is can I bolt a set of 96-98 Non-PI heads and 9psi of boost to this thing, or '99-up PI heads and 6psi of boost, and expect it to hold together? And will it all bolt together in the first place?
 

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Yes either set of heads can work... but for a blower you'll be best served with non pi heads 96-8 and about 6psi for the stock bottom end. You can run 8-9 but you will shorten the life of the engine. I advise against PI heads for this because the increase in CR isnt good for a blower. Get the PI cams and intake though, both of those will help out a bunch.

Edit: And get it tuned with SCT software!
 

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Discussion Starter #7
Yeah, I figured the bumped compression would be a bit of a problem. Thats kind of why I decided to stick within the 6psi range if I went with the PI heads. As for an intake, I should be able to luck out a little there, since I'm planning on useing a roots style blower. Should be able to save a few bucks that way. I guess I'll have to see where I'm at when the time comes. Thanks for the quick replys. :thumbsup:
 
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