Compression ratio too high for 91 octane?

Kern Dog said

Come on, now. There is NO streetable cam that can accommodate 11.8 compression and iron heads. Whatever cylinder pressure that may be "bled off" at low rpms that may reduce detonation there.....will certainly come back as the rpms climb and the cam comes into it's operating range.
I had 10.8 with aluminum heads and a big cam and mine still knocked on 91.

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Camshafts don't "bleed off" anything. That's not how it works. For a camshaft to lower dynamic compression, the intake valve closing event, or IVC must be "late" in comparison. In other words, the compression is "never there" with a camshaft that has 40 degrees IVC for instance, with one that had a 70 degree IVC. The 70 degree IVC closes 30 degrees later, thereby decreasing the amount of mixture that's pulled into the cylinder, so it was never there to "bleed off". And yes, there are indeed camshafts out there that can make 11.8 pump gas friendly with iron heads. The static compression ratio is only one of many variables to look at when considering which fuel you can run.