How to build a proper 4.6 stroker

[Thatblack03]

Hey guys, so I'm in the middle of a 4.6 3v build and need suggestions on a rotating assembly.




The goal is to make 650whp on pump 93 with the ability to go 850whp on e85. It's gonna be a big single turbo (88mm) setup, so I'd like to stroke it for the extra low end power for when I'm not in boost. Unsure of what direction to take. Should I go for a 5.3 build? 5.0 build? 4.75?

I'm planning on a 10.2:1 compression ratio with a MMR 5.0 stroker kit right now. That'd be Manley forged steel 8 bolt crank, Manley H Beams, and .020 over Manley pistons.

I'm gonna be revving very high for a 3v at 8500 rpm, so I need to know if this rotating assembly and stroke will take the abuse and if not, which one would. Before you ask, yes. I did mean to type 8k rpm. I'll be running Jesel followers, Jesel solid adjustable lash adjusters, Comp 26125-24 .650 lift springs, and a set of Comp 127650 cams. I'm thinking the limiting factor will be head flow, which a little boost can fix.

Appreciate any help here, I'm pretty clueless when it comes to engine building. I'm not opposed to buying everything separately, but I would prefer a kit.

 

[Dino Dino Bambino]

Your real limiting factor is going to be piston speed. A longer stroke will necessitate a lower rev limit in order to keep the mean piston speed to no more than 5000ft/minute (what the best all forged bottom end production engines are achieving).

3.80" stroke = 7900rpm
3.75" stroke = 8000rpm
3.65" stroke = 8200rpm (MMR 4.75L stroker crank which is modified Coyote crank)
3.54" stroke = 8500rpm (stock stroke of Modular 4.6)

Therefore your best bet would be to use a Ford Performance Boss 5.0 iron block for its larger 3.70" cylinder bore size in order to maximize valve area and head flow without valve shrouding, while using a stock 3.54" stroke forged crank e.g. '03-'04 Cobra Terminator unit.
The highest revving production (and race) engines are generally "oversquare" with a bigger bore and a shorter stroke. The aforementioned combination will yield a cylinder displacement of 304.8ci or 4994cc (5.0L), which is the same as Ford's famous 5.0L Cammer engines except the Cammer was built on a sleeved Modular aluminium block.