Raylar

I agree here guys. If Edelbrock had done that test with a typical high performance marine wet exhaust and that camshaft they may have seen a good deal of water messing up the dyno numbers and engine internals!
Its always easy to run big cams in an engine for bigger HP numbers at higher rpms on a dyno when there is no water present cooling the exhaust system and exits! The other item to consider is how long will that piece run at those rpms in a boat under those type of loadings.
Stay with Bob Madera's recommendations on heads, cam, intake and exhaust and you will be where you want to be with a reliable system provided you upgrade the stock ZZ502 GM block for those rpms if that's where you intend to run at!
Old Chinese Proverb Says " If it were easy, anybody could do it!"
Only a few novices do, stay with the experts!

Best Regards,
Ray @ Raylar

ROTAX454

Agree and disagree on the short block. I do know of many performance marine ZZ502 applications that had trouble free years of service. Course, that was in stock trim at the 5200 rpm level. The ZZ502 short block has good internal parts and is a stout piece.

However, agree on the marine use beyond the "spec" area of this motor. Most will agree that at a minimum, a disassembly and inspection of the short internals is in order. Beyond that is at the guidance of your professional motor builder (balancing, ring set, bearing tolerance, etc) Idea: Contact RMbuilder on this site. He knows the ZZ502 and where they are built for GMPP.

I know of a performance shop that at one time offered a "blueprinted" ZZ502 short block with a piston ring set change. I will check to see if they still offer it and get back to you.

Kidnova

Ran the bajeebers out'a my crate ZZ502/502 for 4 seasons without so much as a hick-up, but kept it under 6000 R's. It is a "mass produced" engine so I guess some bad one's would get through.

I agree with the others... rmbuilder can take care of what you need, and then some.