Originally posted by HybridSS
Its not really HP levels. It generally two seperate items that kill bottom ends.
1) too much cylinder pressure in the way of a power adder such as nitrous...and most of the time its detonation that is the kicker.
2) Too high rpm. Rod bolt failure.
#1 actually does NOT always compund #2. If you can tune well in between both...you have a good recipe for long lasting power.
But...having said that...id say 550 rwhp.
I know of one stock bottom that has been going strong at 550-600 rwhp for quite some time now 
So actual power isn't the culprit? Lean conditions and detonation are the biggest problems.
I guess if you cross that line, break your bottom end, well, It needed to be replaced anyways.
