5.4 engine questions

[Bornstanger]

hey all i was hoping you guys could clear up some confusion i have about the 5.4 engine. from what i understand, it has the same bore as the 4.6 block, but uses a longer stroke to obtain its displacement. i also hear that 4.6 heads will fit on it and all, but not the intake. if the block is the same since it uses a longer stroke to gain its size, then why do people need to use intake spacer to make cobra or gt intakes fit it. also i notice that some people use navigator heads. if the cobra heads fit, wouldn't you want to use them since they flow better...at least i assume they do. any and all responses to help me understand these things better will be appreciated.

 

[Bornstanger]

time for ye ole bump

 

[fiveofanatic]

The 5.4 block is taller, I assume to fit the longer stroke. The intake won't fit since the heads move further apart with the increased height.

Navigator heads are DOHC/4v. I do not know if they flow better than same-year Cobra heads or not.

 

[Bornstanger]

ahh, well that answers some of my questions. thanx, and keep the explanations coming.

 

[GTblack_00]

the block has a .8x higher deck height, intake has to be .8x wider, also navi heads flow almost the same but have a larger intake port to support the stroked condition the 5.4 presents as they were originally designed and optimized for 3.7 stroke not 4.1x.