Back in the '70s, when they destroked the 340 to 305 so they could run the engine in Transam. They found a problem with the oiling in the upper rpm ranges. Something like 7500 rpm. The fix was a cross over tube from one oil galley to the other one. The holes had to be drilled at specific angles, etc.
For what it is worth I put together a 318 in the late '70s that I regularly ran to 7200 rpm without any problems. But then I was aware of the above limitations. The engine was a basic DC engine with a 340 crank. So it was strong enough for the abuse.
Every engine has there limitations, some of them may not have been found yet. The \6 may have a limitation on how much oil is needed to oil the cylinders and cam lobes and we just don't know it yet.
And I think I will stop stealing this message thread.
