Anybody break a stock block, if so at what hp?

Filling it, or 1/2 filling it, really changes the breaking point. My comments are about full wet factory blocks, and no boost. With a fill they'll go a bit higher as long as the walls are good and EFI turbos especially make "safe" power. Those engines will far exceed what a N/A or N2O engine can do.

To be honest I think a wet factory block can take 650hp no problem, or atleast I would have no problem pushing it to that and even more...Just my opinion, but I really do think the SBM's are tough. Obviously boost brought in nicely is much less harder on the block, and the tune is everything