Sky is not the limit. What would a properly race prepped 409 engine block handle (blower, turbo, NITROUS)? 1000+hp on a factory cast block? If so, which casting? Seen lots of high HP motors but who has pulled the most out of which blocks? Z12 set up makes it easier to hit big numbers but what happens when I put a super charger/turbos with those Z12 heads and a shot or two of nitrous? Aluminum blocks not included. Who has hit the highest number before going NUCLEAR? These engines are designed with a slide rule. What can be considered safe is dependant upon the parts used, builders skill and experience.