11psi on stock internals?

speedytang said:

I have done a lot of repairs on the 3.8 in the Thunderbird and Cougars and they usually have overheating problems that end up being cracked head. How are these engines staying together under boost when stock high mileage cars usually have head problems. I have over a dozen head gaskets and intake manifold gaskets in the shop because these are popular cars to come into the shop. I started buying heads at the yard to give people cheap options. When did Ford change the size into 3.9 and was internal changes made to the cooling jackets to keep the cars from cracking heads? Thanks

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halfway through 1996 is when most agree ford changed the water jackets in the 3.8 to prevent head gasket or head cracking which was common not only to supercoupe 3.8 but all others as well

in 1999 ford went to the splitport heads wihich have 2 intake runners/ cyl and can be bolted to older "singleport" pre 99 blocks 94-95 mustang blocks are not the best to mod because of the waterjackets but with newer 97+ heads and graphitic headgaskets will generally be ok. 2001+ blocks are the best because of a main girdle,windage tray, and thick main webs.

they changed the bore and stroke to 3.80x3.46 to = 3.9L first in the windstar van in 03 then in the rwd mustang block in 04. the 4.2L F-150 and FWD 4.2 windstar engines are 3.81x3.74 where the old 3.8 is 3.81x3.39

hope that clears things up alittle