A 454 Mag 385 hp has all the steel internals of a 502 mag.
The diameter of the 454 is 1.250
The diameter of the 502 is 1.470
The difference is 0.220 (220 thousandths)
Can this be done? and then can you get your ECU reflashed and have a 502?

http://www.offshoreonly.com/forums/s...ore+stroke+502

OOPS
Meant to say 4.250.

So I guess the article mentioned above says that it can be done.
Has anyone ever done this? Is it too much bore?
Would it be better to go the 496 route?

No, they are different blocks. The 502 is a siamese block.

No you can't bore a 454 to ,make it a 502, not enough cylinder thickness . The 502 is a different block although the stroke is the same. Go to a 4 1/4 stroke and make it a 496.You can bore your 454 to a 60 over with no problems. John

Got it !!!!!!!!!!!!!
Thanks guys.

If the 454 Mag is MPI, after the bore and stroke to 496, can the ecu be reprogremmed for the new size?

What exactly is your goal?????? To make more HP?????? or something more specific????????

Make more power at 3500 rpm.
swing a larger prop in an inboard application.

Whipple Supercharge it. Make 600hp and lots of midrange torque.