does anyone know how much boost the bottom end on a 5.9 magnum can take. I would like to know I want to make 600 hp at the crank.
just won't to see what I need to budget for.

 

i know absolutely nothing about the 5.9 magnums. i do know a little about the older 360's.
the 360 had cast cranks, i think the magnums do also, and from my readings cast cranks don't like to make over 500hp.
i do believe the 5.9 have better pistons than the 360 so they should stand 600hp.
if i were building i would buy a bottom end kit with pistons and then crank the boost. it will be cheaper in the long run to do it this way.

 

360 Magnum and 360 LA differences........... Magnum has bolt holes mid way of the block for the 2nd gen mounts, but still has the LA mounts, and it has bolt holes for the crank sensor on the right side at the back of the block, it's balanced different than the LA was but still external, rings are thinner, and oils through the push rod not the rocker shaft like the LA. Intake bolts are straight up and down, not at an angle like the LA. 500hp is pushing it on the stock bottom end, keep around 5psi boost.

 

I don't like cast cranks period, I seen a post on another forum that the crank broke at one of the journals. It was due to worn main bearings allowing it to flex. Any performance build go with a forged crank. In your case better rods and pistons wouldn't hurt either if you want to run more boost.