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I've been gone for a while, so maybe this has been covered, or perhaps I just missed it somewhere.

It seems that when deciding whether to do a hybrid or a reg. 3.0L the big decision is what compression do you want? Right? Now to my knoledge it seems like more people are sticking with just a "regular" swap with the 3L block and head. So if the 3L head flows more air, why not mill the head a millimeter or so and bump your compression a point or so that way???

Maybe there is an issue with that, or maybe no one has ever done it?? I was just curious. Thoughts??
 

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Piston to valve clearance - Simple as that. Duratec clearance is nominally around .100". Keep in mind that .100" is .09x" or .08x" when everything "stretches" at high speed (measured in thousandths of an inch, but still measureable). So the question becomes "how close is too close and still retain a 'safe' distance"? Better to go with higher compression pistons that have built-in valve reliefs to bump the 10.0:1 compression of a full 3L.
 

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You can go anywhere from 9.5 to 11.25 just based on which heads you use and what chamber work you do to them.
That's more then enough range to generate the CR you want for any project. Save maybe a high boost, super huge turbo project. A typical turbo setup would perform a lot better with more compression then the 8.5 or 9 to 1 used in a project like that.
 
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