I noticed on the Mustang V6 specs PDF from Ford that they list the bore of the 3.7 V6 as 95.5 mm. Based on the information gleaned from various articles, Modular family bore spacing is 100 mm, and if I'm not mistaken, the 3.7 V6 is a member of the Modular family? (See EDIT below -- looks like Duratec are not also Modular, but instead a completely different engine family).

I found this interesting, as the mag article on the 5.0 V8 said that they made the bore on the 5.0 V8 as large as they could, with an end result of a 92.2 mm bore. Meanwhile, the 3.7 V6, which makes similar HP/L with similar compression, has a bore over 3 mm more. This would seem to support the idea that the 5.0 V8 block was built to handle quite a bit more power, whereas the 3.7 is probably not. Though it leaves me wondering why they couldn't shave away more aluminum and use a thicker cylinder liner. Anyway, I just thought it was interesting.

EDIT -- just found some info that suggested the Duratec engines have a 102mm bore spacing, which would indicate that they are not of the Modular family (assuming it is indeed true that Modular engines are always 100mm bore spacing). I don't think there is such a thing as a Duratec V8, and Ford's manufacturing equipment probably is not capable of it (a good reason why they wouldn't consider making a Duratec V8 for the 2011 GT). Interesting that an engine family for smaller displacement engines would (or could) have a larger bore spacing than a line of typically larger displacement engines.

 

I have read in multiple locations that the 5.0 shares the same bore spacing as the 4.6, and thats probably why the bore is what it is. That way all they needed was to retool some of the equipment instead of replacing it.

 

This!