390 Hp?

[Deimos140]

Whats the big displacement and horspepower you can build a 390 big block ford?

[Barry_R]

Never been over 550 HP on a 390. They can go decent size but small bore. The 4.250 x4.080 445" is common, but theoretically you can get a low cost 4.375 stroke crank & go larger yet. Never built a 390 like that 'cuz the $900 custom piston cost is out of context for the average 390 builder.