Just to be clear, I did NOT say that a later IVC doesn't reduce cylinder pressure at lower RPM. What I said, and then referenced people waaaay smarter than I am in this arena, was that you can't calc a single DCR value and use it for an accurate build parameter and measure of octane requirement. And, that the late(r) IVC approach is basically a crutch with limitations on its effectiveness.

If I had VVT and a computer-controlled ignition that detects knock, etc. and could also adjust the timing as necessary, then that would be a highly sophisticated Band-Aid for the basic scenario of excessive cylinder pressure.

How many people on this board are using that sort of technology w/ their "traditional" SB / BB / Gen II Hemi builds?

Someone asked where the correlation between DCR and octane was made: David Vizard, well-known engine tech writer, has a chart he's used in articles and his books that I posted below.

I own a LOT of DV books and have learned a bunch from him, but this stuff can't be interpreted as a One Size Fits All thing. You can't even get people to agree on what cam/lift point to use for setting the IVC event, so how can you derive anything about a value for which 5 different people might get an equal number of different answers?