[RV7ator]

How much higher will CHTs be for a 9.6:1 engine v. 8.5:1, everything else being equal on a IO-360-A1A? Imagine you're cruising at 75%, peak power (e.g. ~50 degrees ROP on EGTs), and you have a switch on the panel that can magically toggle between the two compressions.

John Siebold

 

[BobTurner]

By "everything else being equal" I suppose you mean the same Manifold Pressure and RPM? The absolute powers will be different.
BTW EGT 50 ROP is not best power.