They use the same pistons ,5.4 has a longer stroke and taller block so a spacer is needed to put a 4.6 Mustang style intake manifold on a 5.4, other than that I think they are pretty much the same , dont think there is any thing special about 2 valve 5.4 heads , guess I could get them ported but my 4 valve heads are done & work well , bunch of money tied up in them with the cams & CNC work
The heads bolt up the same. The 5.4 is basically just a 4.6 with a taller deck height for the longer stroke. It is a slightly wider block, but that affects the intake manifold rather than the heads. The 2007-2012 GT500s are a 5.4 with 4v heads.
I was thinking a 5.4 bored 40 over with a built bottem end with my 4v heads & a twin turbo set up would Rock in my 2004 Cobra , already have a 5.4 block with steel crank might as well use it, I have a 04 Mach 1 engine with nitrous in it now
What do you mean ? If a cylinder wall got scored there wouldn't be enough left to fix it ? I don't have to bore it at all , there's no wear on them but I was thinking if I'm gonna buy new pistons might as well go bigger , maybe I'll do 20 over then . Thanks for your input
Boring is 10, 20, 30, or even 40 realistically is not going to make any difference in power. It is just thinning the cylinder walls. If you do a twin turbo set up it would be better to have a bit thicker cylinder walls. If you don't have to bore it for anything then i wouldn't. Just hone the walls and call it good. If it is scored from something, then bore it a bit.